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Leaf-Cutter Bees Order Hymenoptera, family Megachilidae (part) Copyright © 1996 by Louise Kulzer This article originally appeared in Scarabogram, August 1996, New Series No. 196, p. 3. I always like late spring and summer, because as soon as my roses start looking good, I can be pretty sure the leaf-cutter bees are not far behind. Leaf-cutter bees are solitary bees in the family Megachilidae (but remember, not all megachilids cut leaves). Those that do cut leaves use them to line their nests, which are constructed in a variety of places, such as tunnels in the ground, under stones, in the pith of brambles (Frost 1959) or excavated in wood. Two species of Megachile (from Howard 1903) [Most megachilids use pre-existing holes and do not dig their own burrows. Of 20 genera in the Pacific Northwest, three (Trachusa, most Megachile, some Hoplitis) use leaf pieces and many Osmia (a large genus also including the mason bees) use chewedup leaf (Stephen et al. 1969).] Actually, it's a bit more elaborate than just lining the nest burrow. Leaf-cutter bees construct several cells from the leaf pieces they collect. The cells are positioned end to end in a long burrow. Several circular leaf pieces form the bottom, then oblong pieces are placed along the sides to form a "thimble." This thimble is then provisioned with nectar and pollen, and an egg is laid in it. Then the bee cuts more circular pieces to close the cell. Once the cell is closed, the bee starts another cell above the first, until the whole cavity is filled. Like all solitary bees, the female leaves the nest after it is closed. The grubs fend for themselves on the nectar and pollen. The adult leaf-cutter bee is smaller than a honey bee, dark, often hairy, with a prominent pollen basket below. Females are workaholics, and are a delight to watch because, being so intent on cutting leaves, they usually ignore a nearby observer! The leaf sections are cut with the mandibles, and the bee forms an arc with her head along the leaf edge to make the circular shape. (They remind me a little of an electric can opener, only with much more personality.) Leaf-cutter bees are most notorious for cutting circular and oval holes in rose leaves, but I have seen them gather Hypericum sp. (St. John's wort), and this year they are particularly attracted to my vine maple. None of these plants are in the same family either, so that's not it. I think they choose plants that have a specific texture and thickness, much as one might choose paper of a certain weight for a report cover. It would be interesting to compare observations, fellow Scarabs! Next time you see round or oval holes in your rose leaves, notice if they are regular and neat in outline (rather than ragged, like beetle damage is). If so, don't be dismayed. Just wait quietly and you may be rewarded by seeing first-hand the efficient, elegant work of the leaf-cutter bee. References Frost, S.W. 1959. Insect Life and Insect Natural History. Dover Publications, NY. Leaf-cutter bee damage on rose. Note both oval and circular cuts. Stephen, W.P., G.E. Bohart, & P.F. Torchio. 1969. The Biology and External Morphology of Bees, With a Synopsis of the Genera of Northwestern America. Agricultural Experiment Station, Oregon State University, Corvallis. Leafcutter Bees no. 5.576 by W.S. Cranshaw 1 Quick Facts... Leafcutter bees are native bees, important as pollinators. Leafcutter bees are not aggressive and have a mild sting that is used only when they are handled. Leafcutter bees cut the leaves of plants. The cut leaf fragments are used to form nest cells. Leafcutter bees nest in soft, rotted wood or in the stems of large, pithy plants, such as roses. Leafcutter bees are important native insects of the western United States. They use cut leaf fragments to construct their nest cells. They often are essential pollinators of wild plants. Some leafcutter bees are even semidomesticated to help produce alfalfa seed. However, their habit of leaf cutting, as well as their nesting in soft wood or plant stems, often attracts attention and concern. Life History and Habits Most common leafcutter bees (Megachile spp.) are approximately the size of the common honeybee, although they are somewhat darker with light bands on the abdomen. They also have different habits. Leafcutter bees are not aggressive and sting only when handled. Their sting is very mild, much less painful than that of honeybees or yellowjacket wasps. Leafcutter bees are solitary bees, meaning that they don’t produce colonies as do social insects (honeybees, yellowjackets, ants, etc.). Instead, individual female leafcutter bees do all the work of rearing. This includes digging out nesting areas, creating nest cells and providing their young with food. Adult females may live up to two months and lay some 35 to 40 eggs during this time. Leafcutter bees nest in soft, rotted wood; thick-stemmed, pithy plants (e.g., rose); and in similar materials that the bees can easily cut through and excavate. Nest tunnels may extend several inches deep and coarse sawdust may be deposited at the entrance. This sometimes causes confusion with other wood nesting insects such as carpenter ants. However, leafcutter bees restrict their tunneling to soft, rotted wood and do not cause damage to homes or other wooden structures. There also are concerns about leafcutter bee nesting in rose canes, excavating the pith of pruned canes. Leafcutter bees sometimes nest in the largest diameter rose canes but cause little damage because they restrict tunneling to the pith and rarely girdle cambium. Furthermore, other insects, including various hunting wasps (Pemphredon species) and small carpenter bees more commonly tunnel and nest in rose canes. After the nest is made, the bees collect fragments of leaves to construct individual nest cells. The bees cut leaves in a distinctive manner, making a smooth semicircular cut about 3/4 inch in diameter from the edge of leaves. Although they cut many types of leaves, leafcutter bees prefer certain types, notably rose, green ash, lilac and Virginia creeper. This injury often is only a minor curiosity. However, where leafcutter bees are abundant and concentrate on cultivated plantings, the removal of leaf tissues can be damaging. Serious damage most often occurs in isolated rural plantings. Leafcutter bees do not eat the cut pieces of leaves that they remove. Instead, they carry them back to the nest and use them to fashion nest cells within the previously constructed tunnels. Then they provision each leaf-lined cell with a mixture of nectar and pollen. The female lays an egg and seals the cell, producing a finished nest cell that somewhat resembles a cigar butt. A series of closely packed cells are produced in sequence. A finished nest tunnel may contain a dozen or more cells forming a tube 4 to 8 inches long. The young bees develop and remain within the cells, emerging the next season. There are a great many parasites that act as important natural enemies of leafcutter bees. As a result, leaf cutting activity may vary widely from year to year. Parasitic bees and wasps, velvet ants and certain blister beetles are among the most important enemies of leafcutter bees and other solitary bees. At least one species of leafcutter bee is cultivated for agricultural use in Colorado. Megachile rotundata is used to pollinate alfalfa grown for seed, a function that it does far more efficiently than honeybees. These leafcutter bees are provided with predrilled “bee boards” that they use for nest construction. At the end of the season, the nest cells with developing bees are collected and carefully stored, to be released the subsequent season when alfalfa blooms. Control Insecticides are ineffective for preventing leaf cutting. The only known control of leaf injuries is to cover susceptible plants with cheesecloth or other loose netting during periods when leafcutter bees are most active. Numbers of leafcutter bees in an area can be reduced if breeding sites are eliminated, although these might be diffi cult to detect. Look for rotting boards with sawdust pushed out of excavated tunnels or thick stemmed plants with hollowed openings. To prevent leafcutter bees from tunneling into rose canes, seal exposed pith as canes are pruned. This can be easily achieved by placing a thumb tack, bit of sealing wax or white glue on the opening. Colorado State University Extension entomologist and professor, bioagricultural sciences and pest management. 1 Orchard Mason Bees This page offers WWW links outside WSU as an option for finding further information. No endorsement of product or information is implied by including this link. The orchard mason bee (Osmia lignaria) is a gentle beneficial insect that has potential as a pollinator of apples, cherries, and other tree fruits. It is found throughout most of North America, particularly in wooded areas but often around homes in towns and cities. Homeowners sometimes become concerned when they see the bee entering cavities under shake siding or investigating nail holes or other cavities in wood during March through early June. These are not destructive insects, since they do not excavate holes in the wood, though they will clean out loose debris. No controls are recommended, since no damage is done. To prevent the bee from nesting, holes may be filled with caulking. The orchard mason bee is usually slightly smaller than a honey bee and a shiny dark blue in color. The actual size of the bee depends largely upon the size of the hole in which it grew. Males (Fig. 1) are smaller than females, have longer antennae and an additional tuft of light colored hairs on the face. Females (Fig. 2) have hairs on the underside of the abdomen, called the "scopa", adapted for carrying pollen. Fig. 1 Male orchard bee. Note the long antennae. (The red coloring is caused by Chaetodactylus sp. mites riding on the bee.) Female orchard mason bee on blossom. Fig. 2 The female approaches the flower from the top, transferring pollen from other flowers in the process. Nesting Habits The female uses existing holes in wood for a nest. She chooses holes slightly larger than her body, usually 1/4 to 3/8 inches in diameter. The bee first places a mud plug at the bottom of the hole, then brings in 15 to 20 loads of nectar and pollen which she collects from spring flowers, including apples and other fruits. If you watch the bee closely as she enters the nest, you can see the pollen on the underside of her abdomen. When the female has provided a sufficient supply of food for the larva, she lays an egg and then seals the cell with a thin mud plug. She then provisions another cell, and continues in this fashion until the hole is nearly full. Finally the bee plasters a thick mud plug at the entrance (Fig. 3). Some wasps and leaf-cutter bees also build nests in such holes but their nests can be distinguished from the orchard mason bee nests by characteristics of the plug. The plug of the mason bee is always rough while the wasp prepares a smooth plug.(Fig. 4). Leaf-cutters seal the holes with chewed-up leaves. Fig. 3 Orchard mason bee putting entrance plug in her nest. Fig. 4 Trap nest with holes filled by female bee. Note smooth wasp plugs on the right. The female orchard mason bee lives for about a month and can produce one or two eggs each day. The larva hatches from the egg after a few days and begins to eat its provisions. When the pollen-nectar mass is completely eaten in about 10 days, the larva spins a cocoon and pupates within the cell. Near the end of the summer the bee transforms to the adult stage but remains in the cocoon throughout the winter. In the spring, when the weather has warmed up sufficiently, the males begin to emerge by chewing their way out of the cocoons and through the mud plugs. The females, which are almost always in the inner cells of the tunnel, emerge several days later. One or two weeks may be required for all the bees to emerge during cool weather. Females mate soon after emerging, then begin nesting in 3 to 4 days. The bees forage on a number of different flowers. In wooded areas, they seem to prefer ballhead waterleaf. In urban areas, dandelion and Oregon grape are commonly visited, in addition to cherries and apples. This Bee Is Gentle The orchard mason bee is non-aggressive and will sting only if handled roughly or if it should get trapped under clothing. It is less objectionable than the honey bee as a pollinator in urban areas and should be encouraged. Efforts are being made experimentally to develop large populations of these bees to use as a supplement to honey bees for fruit pollination, much as the alfalfa leafcutting bee was developed for alfalfa seed pollination. Collecting Orchard Mason Bees If you wish to develop populations for pollinating a home or commercial orchard, you can set out trap nests to collect the bees. Trap nests can be made by drilling holes 1/4 to 3/8 inches in diameter and 3 to 6 inches deep in pine or fir 4x4's. A "brad-point bit" leaves a nice, smooth hole. Alfalfa leafcutting bee boards with hole diameters of at least 1/4 inch can also be used. Attach the boards to a house or other structure where you have seen the bees. Some protection from rain is desirable. You may also place boards on dead trees or posts in wooded areas near streams where there is a good supply of mud for nest construction and wild flowers on which to forage. Position boards where they will receive morning sunlight. Put the nests up in March before the bees begin nesting and remove them in early to mid-summer when nesting is completed. If the boards are stored outdoors over winter (under cover to protect them from rain and snow) the bees will usually emerge in March and April. They should forage for pollen during the period of cherry and apple bloom and afterwards, if sufficient other flowers are available to them. Using the Bee in Orchards If you wish to develop large populations for orchard pollination, you should store the nests under humid refrigeration at 35 to 40° F. This will permit control of emergence time and reduce predation and parasitism by the insect enemies of the bees. Do not place the nests in storage until September or October to assure complete development of the adults. The following spring, place the boards in the orchards in plywood shelters facing east to catch the morning sun. To hasten emergence, incubate the boards at room temperature for 24 hours before placing the bees in the orchard. The boards and some new nesting material should be in place a few days before apples begin to bloom, or earlier if other fruit bloom such as cherries, is available. Provide 5001000 filled holes per acre. These should contain 750-1000 females, assuming an average of 1 1/2 females per hole. Males also visit flowers, but they do not live long and are not as effective as pollinators. Competing flowers such as dandelions should be mowed as soon as the fruit begins to bloom. If no natural mud source is available near the nesting shelters, dig a shallow hole, line it with plastic, and fill it with moist soil. A simple drip irrigator can be made from a plastic bucket and a piece of drip irrigation tubing to keep the soil moist. Developing large populations of the bees may be a slow process under orchard conditions; the short duration of bloom does not allow the bees to accomplish maximum reproduction. The orchard mason bee also has a tendency to fly away rather than using or reusing nests in the near vicinity. However, relatively large populations have been developed in 2 or 3 years in urban situations. Once established, orchard bees will nest in containers filled with large-diameter drinking straws or paper tubes folded in half. Nature Study In addition to their value as pollinators, orchard mason bees are fascinating insects for nature study. Observation nests can be fashioned from transparent plastic or glass tubes placed in a box that can be opened for observation. A film and video, The Orchard Mason Bee, depicting the life history and management of the orchard mason bee is available for rent from the WSU Media Materials Services, Holland/New Library, Washington State University, Pullman, WA 99164. Phone 509/335-7664 for loan availability. Filled Orchard Mason Bee observation nest. What Are They? Orchard mason bees are native North American bees. They live all across the United States and Southern Canada, but are particularly common in the Pacific Northwest, especially in the Puget Sound area and western Cascade Mountains. They are also called "blue orchard bees" and scientists know them as Osmia lignaria. They are beautiful insects, about 1/3 inch long and blue black with a metallic sheen. Unfortunately, they are sometimes mistaken for large flies (look closely - they have 2 pairs of wings and are not interested in garbage!). The females are somewhat larger than the males and the males have a white hairy face. Like all bees, mason bees collect flower pollen as a protein source for their young and get their energy from flower nectar. In shopping for groceries, they carry pollen from flower to flower, achieving pollination. A number of things set mason bees apart from other bees: Solitary: They are solitary. Each female bee builds a nest by herself, lays eggs, seals the nest, and goes about her business. She receives no help from other bees, so there is no colony or "hive" as in honey bees or bumble bees. Live Together: Mason bees are attracted to each other. They like to build their nests in aggregations. Safe: As with other solitary bees, mason bees are gentle and shy. They have a stinger (actually it is an egg guide), but they use it only when they are in serious danger, as when they are purposely caught in the hand. They do not attack to defend their nest or arouse each other in alarm. Specialized Pollinators: Mason bees prefer to forage on flowers in the apple family, including many varieties of apples, cherries, plums, peaches, and similar "stone fruits". Because they specialize on these plants, they are exceptionally good pollinators of them. They will forage on other flowers as well. Hard Working: Orchard mason bees are adapted to a cool climate and can fly in chilly, even drizzly weather. Thus, they are often busy pollinating when honey bees remain inside the hive. Build With Bricks: Like the wisest little pig, orchard mason bees build their nests with bricks (sort of). Each egg chamber in the nest is sealed with a partition of ordinary mud. The entire nest is also sealed with a hardened mud capping. This is why they are called "mason" bees. The above features make orchard mason bees the perfect pollinator for those who have a small number of fruit trees, but may not want to manage honey bee hives. They are also a fascinating wild creature that can be easily encouraged to colonize the backyard garden environment, to the benefit of the gardener, orchardist, homeowner, and nature lover. Mason bees are totally safe, even around children and pets. Keeping Female mason bees make their nests in hollow cavities. In nature, these are found in the fissured bark of trees or in the emergence holes of tree-eating grubs. Mason bees can be attracted to you yard. They may already be in your neighborhood, especially if you live in the Puget Sound region. To make mason bees a part of your home life, simply provide them with nest holes and make sure they have plenty of flowers to feed on. The ideal nest hole is 5/16 to 11/32 inches in diameter and 4 to 8 inches deep. The bees will nest in a wide variety of such cavities. Straws and holes drilled in boards are commonly used. But to produce happy and healthy bees and to avoid disease build-up, you should give the bees quality housing. Problems Orchard mason bees have problems, just like all creatures. They have certain requirements in nest placement, preferring a warm, dry situation. They must have adequate flowers to raise their brood. And finally, they are subject to diseases, parasites, and predators. These include fungal diseases of the developing bees, various types of mites, which compete with the larval bees for foodor parasitize them, and predatory insects or larger predatory animals like woodpeckers. The most serious of these problems are the diseases and parasites. Straw Systems Bare wood holes are acceptable to mason bees, but over time the become fouled with debris and germs. If not cleaned, the hole loses its attractiveness as a subsequent nest cavity. Mason bees tend to "go away" from such nest blocks after the first year or two. Diseases and parasites may build up in unhygenic nest blocks. The best nest system for orchard bees is a smooth wood hole with a porous insert or liner (straw) which can be replaced each season. The concept of straw inserts was developed by USDA scientists in studying mason bees. With a straw system, the filled nests can be removed in the fall, and replaced with new inserts in the spring. The new bees in the nests can be safely stored in a cool environment until it is time for them to begin the nesting cycle and pollinate. Then, simply place the nests near the nest blocks and allow the bees to emerge and re-nest in the new inserts. Mason bee From Wikipedia, the free encyclopedia Mason bee is a common name for species of bees in the genus Osmia, of the family Megachilidae. They are named from their habit of making compartments of mud in their nests, which are made in hollow reeds or holes in wood made by wood boring insects. Species of the genus include the orchard mason bee, Osmia lignaria, the blueberry bee, O. ribifloris, and the hornfaced bee, O. cornifrons. The former two are native to the Americas and the latter to Japan, although O. lignaria and O. cornifrons have been moved from their native ranges for commercial purposes. The Red mason bee, Osmia rufa, is found across the European continent . Mason bees are increasingly cultivated to improve pollination for early spring fruit flowers. They are used sometimes as an alternative, but more often as an augmentation for European honey bees. Unlike honey bees (Apis), they are solitary; every female is fertile and makes her own nest, and there are no worker bees for these species. Solitary bees produce neither honey nor beeswax. They are immune from acarine and Varroa mites, but have their own unique parasites, pests and diseases. Most mason bees live in holes and can be attracted by drilling short holes in a block of wood. They are excellent spring season pollinators and, since they have no honey to defend, will only sting if squeezed or stepped on. As such, they make excellent garden "pets", since they both pollinate the plants and are safe for children and pets. Osmia species are usually metallic green or blue, though many are blackish. Most have black ventral scopae which are difficult to notice unless laden with pollen. They have arolia between their claws unlike Megachile or Anthidium species. The number of Osmia species in North America is probably third in line after Andrena and Perdita. Contents [hide] 1 Life Cycle 2 See also 3 External links 4 Further reading [edit] Life Cycle Home made nest block showing full occupation Mason bee nest cell with egg on pollen bed. Mason bee nest cell with cocoon. Hornfaced bee Osmia cornifrons The bees emerge from their cocoons in the spring, with males the first to come out. They remain near the nests waiting for the females. When the females emerge, the first thing they do is mate. The males die and the females begin provisioning their nests. Osmia females like to nest in narrow holes or tubes, typically naturally occurring tubular cavities. Most commonly this means hollow twigs, but sometimes other similar spaces are used, including empty snail shells (they do not excavate their own burrows, unlike many bees). A female might inspect several potential nests before settling in. Females then visit flowers to gather pollen and nectar, and it will take many trips to complete a pollen/nectar provision mass. Once a provision mass is complete, the bee backs into the hole and lays an egg on top of the mass. Then she creates a partition of "mud", which doubles as the back of the next cell. The process continues until she has filled the cavity. Female-destined eggs are laid in the back of the nest, and male eggs towards the front. Once a bee has finished with a nest, she plugs the entrance to the tube, and then may seek out another nest location. By the summer, the larva has consumed all of its provisions and begins spinning a cocoon around itself and enters the pupal stage, and the adult matures either in the fall or winter, hibernating inside its insulatory cocoon. Most Osmia species are found in places where the temperature drops below 0°C for long durations, like Canada, and they are well-adapted to cold winters. CARPENTER BEES by Mike Potter, Extension Entomologist University of Kentucky College of Agriculture In the late-spring and early summer, homeowners often notice large, black bees hovering around the outside of their homes. These are probably carpenter bees searching for mates and favorable sites to construct their nests. Male carpenter bees are quite aggressive, often hovering in front of people who are around the nests. The males are quite harmless, however, since they lack stingers. Female carpenter bees can inflict a painful sting but seldom will unless they are handled or molested. Carpenter bees resemble bumble bees, but the upper surface of their abdomen is bare and shiny black; bumble bees have a hairy abdomen with at least some yellow markings. Despite their similar appearance, the nesting habits of the two types of bees are quite different. Bumble bees usually nest in the ground whereas carpenter bees tunnel into wood to lay their eggs. Bare, unpainted or weathered softwoods are preferred, especially redwood, cedar, cypress and pine. Painted or pressure-treated wood is much less susceptible to attack. Common nesting sites include eaves, window trim, facia boards, siding, wooden shakes, decks and outdoor furniture. Entrance holes are perfectly round. Nest tunnels are shown Carpenter bees overwinter as adults in wood within abandoned nest tunnels. They emerge in the spring, usually in April or May. After mating, the fertilized females excavate tunnels in wood and lay their eggs within a series of small cells. The cells are provisioned with a ball of pollen on which the larvae feed, emerging as adults in late summer. The entrance hole and tunnels are perfectly round and about the diameter of your finger. Coarse sawdust the color of fresh cut wood will often be present beneath the entry hole, and burrowing sounds may be heard from within the wood. Female carpenter bees may excavate new tunnels for egglaying, or enlarge and reuse old ones. The extent of damage to wood which has been utilized for nesting year after year may be considerable. Control Carpenter bees prefer to attack wood which is bare, weathered and unpainted. Therefore, the best way to deter the bees is to paint all exposed wood surfaces, especially those which have a history of being attacked. Wood stains and preservatives are less reliable than painting, but will provide some degree of repellancy versus bare wood. To further discourage nesting, garages and outbuildings should be kept closed when carpenter bees are actively searching for nesting sites. Liquid sprays of carbaryl (Sevin), chlorpyrifos (Dursban), or a synthetic pyrethroid (e.g., permethrin or cyfluthrin) can be applied as a preventive to wood surfaces which are attracting bees. Residual effectiveness of these insecticides is often only 1-2 weeks, however, and the treatment may need to be repeated. Tunnels which have already been excavated are best treated by puffing an insecticidal dust (e.g., 5 percent carbaryl) into the nest opening. Aerosol sprays labeled for wasp or bee control also are effective. Leave the hole open for a few days after treatment to allow the bees to contact and distribute the insecticide throughout the nest galleries. Then plug the entrance hole with a piece of wooden dowel coated with carpenter's glue, or wood putty. This will protect against future utilization of the old nesting tunnels and reduce the chances of wood decay. Although carpenter bees are less aggressive than wasps, female bees provisioning their nests will sting. Treatment is best performed at night when the bees are less active, or while wearing protective clothing. Carpenter Bees HYG-2074-06 Susan C. Jones Associate Professor, Entomology; Extension Specialist, Household and Structural Pests Carpenter bees are so named because they excavate galleries in wood to create nest sites. They do not consume wood. Rather, they feed on pollen and nectar. Carpenter bees are important pollinators of flowers and trees. Carpenter bees typically are just nuisance pests that cause cosmetic rather than structural damage to wood. Nonetheless, considerable wood damage can result from many generations of carpenter bees enlarging existing galleries in wood. Large carpenter bees belong to the genus Xylocopa. Two native species, Xylocopa virginica and Xylocopa micans, occur in the eastern United States. There also are a number of native carpenter bees in the western United States. This fact sheet primarily pertains to X. virginica, which has the common name of carpenter bee. Figure 1. Carpenter bee. (Courtesy of Kansas State University.) Identification Carpenter bees are large and robust. X. virginica is three-fourths to one-inch long, black, with a metallic sheen. The thorax is covered with bright yellow, orange, or white hairs, and the upper side of the abdomen is black, glossy, and bare (Figure 1). The female has a black head, and the male has white markings on the head. Carpenter bees have a dense brush of hairs on the hind legs. Carpenter bees somewhat resemble bumble bees, except bumble bees have dense yellow hairs on the abdomen and large pollen baskets on the hind legs. Various species of bumble bees and carpenter bees are similar in size. Bumble bees typically nest in the ground whereas carpenter bees nest in wood. Life History Carpenter bees are solitary insects that do not form colonies. Male and female carpenter bees overwinter as adults within their old nest gallery. Adults emerge in the spring (April and early May) and mate. There is one generation per year. The males are not long lived, and the female carpenter bee prepares the nest. Gallery construction is a timeand energy-consuming process, and the female will preferentially refurbish an old nest rather than excavate a new one. When constructing a new nest, the female uses her strong jaws (mandibles) to excavate a clean-cut, round nest entrance hole on the lateral surface of wood in an exposed or unexposed location. This hole is slightly less than 1/2-inch wide, approximately the diameter of her body. She bores into the wood perpendicular to the grain for one to two inches then makes a right angle turn (~90�) and excavates along the wood grain for four to six inches to create a gallery (tunnel). She excavates the gallery at the rate of about one inch in six days. The female bee creates a series of provisioned brood cells in the excavated gallery. The larval provision consists of a mixture of pollen and regurgitated nectar formed into a ball. The female forms a food ball at the far end of an excavated gallery, lays an egg on top of the mass, and then walls off the brood cell with a plug of chewed wood pulp. A female often creates six to 10 partitioned brood cells in a linear row in one gallery, and she dies soon thereafter. Larvae feed on the pollen/nectar food mass, which is sufficient food for them to develop to the adult stage. The life cycle (egg, larva, pupa, adult) is completed in approximately seven weeks, although developmental time may vary depending on the temperature. The new adults typically remain in their gallery for several weeks then chew through the cell partitions and venture outside in late August. They collect and store pollen in the existing galleries, but also spend much of their time just huddled together inside a gallery. These new adults hibernate in galleries because they require shelter during the winter. They then emerge the following spring. Habits Carpenter bees nest in a wide range of softwoods and hardwoods, particularly if the wood is weathered. Eastern species of carpenter bees prefer softwoods such as cedar, redwood, cypress, pine, and fir. The bees can more easily tunnel through woods that are soft and that have a straight grain. Western species of carpenter bees often nest in oak, eucalyptus, and redwood. Carpenter bees attack structural timbers and other wood products, including fence posts, utility poles, firewood, arbors, and lawn furniture. In buildings, carpenter bees nest in bare wood near roof eaves and gables, fascia boards, porch ceilings, decks, railings, siding, shingles, shutters, and other weathered wood. These bees avoid wood that is well painted or covered with bark. The carpenter bee entrance hole in wood may not necessarily be in an exposed area. For example, the inner lip of fascia boards is a common site of attack. Nail holes, exposed saw cuts, and unpainted wood are attractive sites for the bees to start their excavations. Figure 2. Carpenter bee entrance hole in fascia. Figure 3. Carpenter bee staining on siding below the fascia. Figure 4. Carpenter bee gallery exposed in wood. Economic Importance Despite their beneficial aspect of being important pollinators of many trees and flowers, carpenter bees also may be nuisance pests around structures. Carpenter bees are noisy, which may be bothersome. These large bees create alarm when they dive-bomb or fly erratically around humans. In actuality, these are male bees, which are territorial but harmless because they lack a stinger. Only females have a stinger. Female carpenter bees are docile and are reported to sting only if handled. Carpenter bees create a nuisance by excavating round entry holes in wood (Figure 2) and depositing yellowish to brownish streaks of excrement and pollen on surfaces below entry holes (Figure 3). They also produce coarse sawdust from their borings. The carpenter bee gallery system is confined within the wood (Figure 4) and hence is not visible. Carpenter bee damage to wood initially is minor, and carpenter bees seldom cause consequential structural damage. However, their repeated colonization of the same wood can eventually cause considerable wood damage. Carpenter bees preferentially refurbish and enlarge an existing tunnel instead of boring a new one, and a gallery can extend for 10 feet if used by many carpenter bees over the years. Carpenter bees sometimes construct new tunnels near old ones, with infestations persisting for several years. This complex system of tunnels can result in extensive damage to wood. Wood replacement is necessary when the strength of structural members, posts, poles, and other wood products is reduced due to carpenter bee damage. Carpenter bees also may be indirectly responsible for unsightly wood damage when woodpeckers riddle the wood with holes searching for the developing carpenter bees to feed upon. Integrated Pest Management When dealing with carpenter bees, it is preferable to locate tunnel entrances during the daytime, but treat after dark on a cool evening when carpenter bees are less active. Wear protective clothing to avoid any stings during treatment. Prevention Keep all exposed wood surfaces well painted with a -polyurethane or oil-base paint to deter attack by carpenter bees. Periodically inspect painted surfaces, because the coatings will begin to deteriorate due to weathering, leaving exposed wood that the bees then can easily attack. Wood stains will not prevent damage. Consider using aluminum, asbestos, asphalt, vinyl siding, and similar non-wood materials that are not damaged by carpenter bees. Seal existing gallery entrance holes to discourage carpenter bees that are looking for potential nesting sites. Mechanical Measures A non-insecticidal management approach is to deny carpenter bees access to their galleries by sealing each entrance hole. Thoroughly plug the hole with caulking compound, wood putty, or a wooden dowel affixed with wood glue. If possible, also fill the entire gallery system with a sealant. Carpenter bee galleries are a critical resource, since the bees spend much of their time inside a gallery, and they require its protective conditions to survive the winter. Bees that are trapped inside a caulked gallery typically will not chew out due to behavioral constraints. This barrier approach has promise for reducing future carpenter bee infestations. In new nests, the single female often can be swatted and killed, or she can be captured and crushed or otherwise destroyed. Larvae and pupae can be killed by inserting a sturdy wire into the entrance hole and probing into the gallery as deeply as possible. Insecticides A chemical treatment using an appropriately labeled insecticide can protect wood for short periods, especially in the spring and summer when carpenter bee nesting activity is apparent. Dust formulations typically provide residual effects and are effective due to the nature of carpenter bee gallery construction. Precisely inject the dust directly into each nest entrance hole and as deep into the tunnel as possible and also apply it to the adjacent wood surface. Wait for a few days before plugging entrance holes since adult bees should be allowed to pass freely to distribute the insecticide within the galleries. Newly emerged bees also will contact the dust when attempting to leave their gallery. For use as a preventive, an insecticide should be applied to wood in early spring before carpenter bees begin excavating nests. The insecticide kills the bees that contact it on the wood�s surface. However, a preventive approach has limitations because of the difficulty in applying a chemical to all exposed wood on the house where bees could nest. Furthermore, such insecticides usually degrade in a matter of weeks or months so repeated applications are needed to maintain a lethal dose of the insecticide. Some pest management companies report good results against carpenter bees by spraying wood with a microencapsulated pyrethroid, Demand� CS insecticide (registered for use only by licensed professional applicators), which contains the active ingredient lambda-cyhalothrin. A number of other pyrethroids (bifenthrin, cyfluthrin, deltamethrin, permethrin, etc.) also are labeled for use against carpenter bees. Insecticides that act as stomach poisons, such as borates, typically are ineffective against carpenter bees, which do not ingest the wood that they excavate. Click here for PDF version of this Fact Sheet. Bumble Bee or Carpenter Bee? When encountering black, almost round bees buzzing around their home most people do not know the difference between the bumble bee and carpenter bee. There are two basic things to note that should quickly let you know which bee you are seeing: location and activity of bee and certain physical characteristics of the bee. Carpenter bees are most often noticed while they are building and tending to their nests which are simple, round openings in wood structures. If you see a bee that is boring out a perfectly round hole in wood, it is a carpenter bee. For more information about carpenter bees (biology, habits, how to control) go to the Carpenter Bee web page. Bumble bees have a fuzzy abdomen and the Carpenter Bee has a shiny abdomen. General Bumble Bee Information The "Bumble Bee" is a big, hairy, black and yellow bee whose size can range from 3/4 inch to 1 1/2 inch. This insect is often mistaken for a carpenter bee, which closely resembles the bumble bee in appearance. Carpenter bees have a shiny and smooth abdomen as opposed to the fuzzy abdomen seen on a bumble bee. There are over 200 types of Bumble bees in the world. Fifty different types can be found in North America. Each different species will have its own preference to types of nectar and prefers different flowers. The bumble bee is an important, beneficial insect. They pollinate plants and flowers as they forage for food. To gardeners, it is a welcome sight to see these large, flying insects carrying large loads of pollen, flying into and around their flower beds and gardens. While busy searching for food (and at the same time, pollinating plants) bumble bees are rarely a problem when in close proximity to humans. They will actually (in most cases) go out of their way to avoid human contact. Bumble bees will, however, defend themselves if they sense that they are cornered and cannot escape. Most of the time they will fly away from danger but will sting if they are under duress. Bumble bees have very few predators in nature. Skunks are their largest and most destructive predator. Skunks are omnivores that will eat insects, rodents, reptiles, small mammals, worms, eggs, fish, fruit, and plants. When they locate a bumble bee nest, skunks help themselves to bee larvae and adult insects. They ignore the pain of bee stings to get to their preferred foods. The queen bumble bee comes out of hibernation every spring to find a new spot to build her nest and start a new colony. This queen bee was fertilized the previous season and has managed to live through the winter months. The same nesting spot (from previous seasons) are rarely used. A suitable place for nesting is usually on the ground, beneath a flat object. An old mouse hole or similar hole in the ground is preferred if it is underneath an old tarp, flat stone or man made objects such as a deck. The hole chosen by the queen bee is first padded by pieces of vegetation such as dry grass or moss. It is in this padded underground hole that the fertilized queen bumble bee lays her eggs and begins collecting nectar for her soon to hatch grubs. On the grubs emerge from their eggs, the queen bumble bee spins a protective silk cocoon for each grub. It is from this first batch of larvae that 5 to 20 daughters emerge. These daughters of the queen bumble bee are workers who begin immediately start working on building the colony. The queen bee will continue to lay eggs for the remainder of the summer season. The workers work tirelessly to build the colony, collect nectar for the young and also to provide protection for the colony. The first batch (or hatching) of bumble bee workers are smaller than their sisters who will emerge later on when the colony grows larger and healthier. The queen bee uses her energy to begin the nest and this energy (as well as time) is spread thin as she is the sole worker for the new colony. As the colony grows, the eggs and larvae are given more attention and food simply because there are many workers that share the work load. It is at this point in time that larger bumble bees are seen. Bumble bees are often first noticed (in the area of the nest) when this activity of guarding the nest and pollen collecting begins. The worker bees are focused only on their job and will not go out of their way to sting people. It is only if people get too close to their nest or threaten them when bumble bees will sting. Bumble bees do not die after stinging, as do some other stinging insects. Towards late summer, the queen will start to produce drones and young queens. The young queens are fertilized by the drones, then fly off to hibernate. Hibernation usually takes place in dry protected areas such as loose bark. The colony's remaining drones and workers stay in the colony and die during the winter season. The young queens start new colonies in the spring of the year. As mentioned above, bumble bees do not use the same nest though they may nest in an area close by to the original bee nest. Bumble Bee Photo by: Dorling Kindersley Bumble Bee, common name for any of a group of large, hairy, usually black-and-yellow, social bees. They are found primarily in temperate regions of the northern hemisphere, often ranging farther north and higher in altitude than other bees. Fifty species of bumble bees are known in North America. Characteristics Bumble bees are similar to their close relatives, the honey bees, in that their colonies are headed by a queen, who is the main egg-layer, and many workers, who are the daughters of the queen, and in that drones (males) are produced during the mating season. However, the colonies of bumble bees, unlike those of honey bees, only survive during the warm season; new queens hibernate alone to begin another colony the following spring. In addition, there are usually fewer individuals in a bumble-bee colony than in a honey-bee colony, and bumble bees do not use a dance to communicate the location of food to other members of the colony, as honey bees do. Also, although bumble bees collect nectar and store it as honey, they do not hoard large amounts of it, as do honey bees. Because bumble bees are conspicuous and important in nature, their biology has been well studied. They are among the few insects that can control their body temperature. In cold weather, queens and workers can shiver their flight muscles to warm themselves, allowing them to fly and work at lower temperatures than most other insects. Their large size and heat-conserving hairy coats also help them stay warm. These features enable them to live in northern latitudes and alpine altitudes. Bumble bees are sensitive to habitat disturbance. In England, several species are thought to have become extinct in past decades due to land clearing and agricultural practices. Life of the Colony The bumble-bee nest consists of a spherical chamber with a single exit. The queen chooses a preexisting cavity, such as an abandoned mouse nest, in which to begin her family. Most species nest in the ground. The queen forms a small mound of pollen paste in the middle of the nest, lays several eggs in it, and seals it with a small dome of wax. She also constructs a hemispherical wax cup, called a honeypot, in the entranceway floor and fills it with nectar. The queen feeds on this nectar while she incubates the eggs. The newly hatched larvae partially consume the paste in their cells. Later they are fed by the queen through a small opening in the cell wall. When the larvae are fully grown, they spin cocoons in which they metamorphose, eventually emerging as the first workers of the new colony. Subsequent larvae are reared by these workers in individual cells, much as honey-bee larvae are; however, the bumble-bee nest is not organized into flat, vertical combs like that of honey bees but grows instead into a mound of capsule like cells. Toward the end of summer, the queen begins to lay unfertilized eggs that develop into drones. Female offspring produced at this time become new queens, and mating takes place soon afterward. The drones and workers then die, and the new, mated queens fly off in search of safe places to hibernate. Some species of bumble bees, known as cuckoo bumble bees, are parasitic on the nests of nonparasitic bumble bees. They invade the nest, kill the resident queen, and force the workers to raise the young parasitic bees along with the brood of the host colony. Occasionally, the invaders permit only their own young to survive. Cuckoo bumble bees lack pollen baskets because they do not forage for pollen. Pollination Bumble bees are important pollinators of many plants. Both queens and workers collect pollen and transport it back to the colony in pollen baskets on their hind legs. Workers are small if born early in the year, and large if born later in the year. Also, some species of bumble bees are larger than others. Differences in body size, and especially in tongue length, are important in determining which flower species a bumble bee will visit for nectar and may determine which flowers it can pollinate. Bumble bees have long been recognized as vital to the production of certain seed crops. In recent years, bee scientists have developed a means to cause queens to skip their winter hibernation and produce colonies year-round. This has made certain species of bumble bees available for use in pollinating crops they did not before. Bumble-bee colonies are now used extensively in greenhouse pollination of crops such as tomatoes and strawberries. Reproduction and Life Cycle of the Yucca Moth Male and female Tegeticula yuccasella moths use the yucca blooms as a bridal chamber, with the male abdicating all responsibility for the female and the larvae after mating. Mating occurs in the evening hours when the yucca blooms are fully open. When the yucca plant begins its spring bloom, signaling its readiness for pollination, the yucca moth, using her specialized mouth organs, collects the highly adhesive pollen from the yucca flowers' male sex organs, or anthers. Typically secretive - the female yucca moth works only in the darkness between sunset and midnight - and choosy - she seeks the newest of blooms - the yucca moth, once pollen laden, now enters a flower and circles and evaluates the female reproductive organ, or ovary. She may withdraw and renew her search if she finds that another yucca moth has visited the flower ahead of her. Once she makes a choice, she lays eggs in a specific location within the flower's ovary. She then climbs the ovary's stigma and deposits a small fragment of her pollen, fertilizing the flower so that it soon begins producing fruit and the seeds for her coming offspring. With only a few days left in her lifetime, she soon moves on, searching for another acceptable bloom. The yucca moth’s larvae hatch within several days, with the yucca plant - keeping its end of the bargain - providing its fruit for housing and some seed for food. When conditions are right, ideally soon after a nighttime thunderstorm, the yucca moth larvae leave the fruit of the yucca and drop to the desert soil. They burrow down one to three inches. Each creates a cocoon, where it may develop for several weeks to several years before it emerges to renew the cycle.