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The German Yellowjacket (Vespula germanica) Problem in the United States (Hymenoptera: Vespidae)t J. F. MACDONALD!, R. D. AKRP, AND R. E. KEYEU. Associate Professor, Department of Entomology, Purdue University, W. Lafayette, IN 47907; I Entomologist, Department of Entomology, Washington State University, Pullman, WA 99164;2 Research Assistant, Department of Entomology, Cornell University, Ithaca, NY 148533 Yellowjackets are the familiar social wasps which typically build large paper nests consisting of multiple combs enclosed in an envelope (see Greene and Caron 1980). Workers of all yellowjacket species aggressively defend their colony if it is disturbed and such workers are probably responsible for many of the stinging episodes attributed to "wasps and bees" (Fluno 1961, Barr 1974). Although difficult to accurately document, the number of serious reactions and deaths resulting from yellowjacket stings is high enough to have stimulated an increasingly greater interest of medical researchers apiaries in New Zealand, and is a potential threat to apiculture in this country, although significant hive predation is still undocumented (Dejong 1979). Because of the rate and extent of German yellowjacket dispersal, and its successful establishment in many urban centers in this country, we believe an informative paper will be valuable to entomologists, public health officials and control specialists who may have to deal with this spreading problem. We have experienced a marked increase in inquiries from professionals and the public regarding yellowjackets the past few into years the problems of human hypersensitivity to yel- lowjacket venom and venom desensitization methodology. Akre et al. (1980) reviewed the medical importance of yellowjackets, as well as the economic impact of yellowjackets on resorts, campgrounds, lumber operations, fruit harvests, etc., in those areas of the USA periodically experiencing years of yellowjacket abundance. In addition to periodic problems with native yellowjacket species, we are now faced with a new yellowjacket problem. Since the late 1960's, the German yellowjacket, Vespula germanica (Fab.), has become firmly established over much of northeastern North America from Montreal and Ottawa, Canada in the north (Menke and Snelling 1975; Morse et al. 1977) and along the eastern seaboard south into New Jersey, Delaware and Washington D.C. (Lord 1978). Based on recent reports and personal observations, during the past few years the German yellowjacket has spread westward across the northern midwest into Indiana, Illinois and Michigan, and was reported from Winnipeg, Manitoba in 1979 and Minneapolis, Minnesota in 1980. The establishment of V. germanica in this country is a cause for concern since the German yellowjacket, more so than any native yellowjacket, appears to be closely associated with human foods and food processing industries (Spradbery 1973a; Keyel 1980). Moreover, in this country the preferred nesting site of the German yellowjacket is inside structures and not underground (Menke and Snelling 1975; Morse et al. 1977). Both worker foraging behavior and structural nesting bring the German yellowjacket into conflict with humans, and this species is emerging as the most important urban/industrial pest yellowjacket (Akre et al. 1980). In addition, the German yellowjacket is a serious pest of t Journal paper number 768v, Purdue Agricultural Experimem Station, and Scientific paper number 5381, Washington State University, College of Agriculture Research Center, Pullman. Work supported by Purdue Agricuhural Experiment Station project number 58045 and project number 4037 at Washington State University. Financed in part by NSF Grant BNS-76-81400 to Washington State University. Received for publication April 14, 1980. "'19XO Entomological Society of America and have become aware that many entomologists, and most public officials and the public, possess little understanding of social wasp biology and, accordingly, will likely not be able to deal effectively with this new problem. Here, we summarize the natural history of the German yellowjacket and provide practical information on safe and effective control measures. History of the German Yellowjacket in the United States Vespula germanica is native to Europe, northern Africa, and temperate Asia (Spradbery 1973a) but has been introduced into numerous countries, including several in the Southern Hemisphere: New Zealand (Thomas 1960); Tasmania (Spradbery 1973b); South Africa and Chile (Edwards 1976); and Australia (Smithers and Holloway 1977). Once introduced and established, the German yellowjacket became a very serious pest in New Zealand (Thomas 1960; Perrott 1975), and has always been a serious pest over much of Europe, particularly in urban, recreational, and even commercial areas (Spradbury 1973a). Based upon a few collection records, V. germanica was periodically introduced into northeastern North America in the past century, but did not become established until about 1968, apparently in Maryland (Morse et al. 1977). Records of the early establishment and dispersal of V. germanica unfortunately are limited to Menke and Snelling (1975) and Morse and co-workers at Cornell University. In 1972, V. germanica workers already made up about half the yellowjackets in student collections at Cornell, and by 1974 the German yellowjackel had become the major pest yellowjacket foraging at human food sources and nesting in human structures in the Ithaca, New York vicinity (Morse et al. 1977). Although the proportion of structural yellowjacket nests due to V. germanica in Ithaca, NY has declined from 75% in 1972 (Morse et al. 1977) to 35% and 39% of such nests in 1977 and 1978, respectively, V. germanica has remained the most abundant yellowjacket at human food 0013-X754 80 0404-3607$00.75 436 0 Vol. 26, no. 4, 1980 ESA BULLETIN sources even when scantily represented on nearby natural carbohydrate sources such as honeydew (Keyel 1980). Morse et aI. (1977) attempted to trace the spread of V. germanica westward during the summer of 1976. They collected it throughout northern Ohio, and in the same year a few specimens appeared in student collections at Purdue University. However, V. germanica was present in northeastern Ohio earlier since we have workers collected Aug 5, 1971 from Rock Creek, Ohio. Interestingly, the German yellowjacket has been perceived as being different from native species. For example, by the mid-1970 people in northern Ohio and around Temperance, Michigan noted yellowjackets they called "newcomers." Few yellowjacket problems occurred in these areas over the previous 10 years or so, but now these "newcomers" were abundant enough to cause concern as they scavenged on fallen fruit, other sweets, in animal carcasses, and on meats eaten by humans. By 1978, V. germanica was a cause of problems in southern Michigan, and 2 colonies were discovered on the Michigan State University campus that summer (P. Landolt, pers. comm.). Initially reaching west central Indiana in 1976, V. germanica has become the most reported yellowjacket in major urban areas throughout the state, and is the most common yellowjacket species on the Purdue University campus. Indeed, in 1978, 11 colonies were found in buildings within a 1/2 kn) radius of Entomology Hall. During late summer and autumn 1978 and 1979, the Department of Entomology, Purdue University, the Indiana State Board of Health, Indianapolis, and the State Entomologist's Office, Indianapolis, each were receiving several calls weekly regarding yellowjacket problems. Most reports were from homeowners discovering yellowjacket colonies inside their homes, but several food processing industries called seeking a remedy for yellowjackets disrupting plant operations. Such problems had not been reported in Indiana prior to 1978. In addition, pest control operators reported a significant increase over the past 2 to 3 seasons in calls to treat structural colonies. Based on the above accounts and numerous requests for information and control recommendations from urban areas in Indiana, Illinois, and Ohio, the major dispersal route of V. germanica during the mid-1970s was westward across the upper Midwest, apparently from one urban area to another. The saltatorial spread of V. germanica is probably related to the synanthropy exhibited by this species making dispersal of inseminated queens via commerce very likely. In fact, entry into New Zealand in 1944 was traced to overwintering queens in airplane engine crates shipped into the country from England (Thomas 1960). Once introduced into a new area, dispersal is again probably facilitated by lines of commerce. Study of the initial invasion in New Zealand showed founding queens ventured less than I000M from a parent colony before establishing a new colony, and the rate and pattern of dispersal was best explained by the close relationship with rail and highway routes (Thomas 1960). 437 Natural History of the German Yellowjacket Vespula is divided into the V. rufa (L.) and V. vulgaris (L.) species groups both on the basis of morphology and several aspects of biology. Most significantly, workers of the V. vulgaris group, in addition to capturing live insect prey, turn increasingly to scavenging in late summer and autumn. Particularly attractive meat sources include animal carcasses, dead insects, meat in garbage, and numerous meats eaten by humans. Foraging for the latter 2 sources plus for sweets found in garbage, at picnics, and in association with some food processing industries frequently brings workers into conflict with humans. Furthermore, V. vulgaris group species often attain very high population densities in recreational and residential areas where their large colonies may remain active into early winter. Thus, colony duration may be I to 3 months longer and colony size much larger than that of other temperate social wasps. Because of worker scavenging behavior, large colony size, long seasonal cycle, and frequent high population density, species of the V. vulgaris group constitute our most serious social wasp problem (MacDonald et a!. 1976). The V. vulgaris group in North America consists of 4 native species: the eastern yellowjacket, V. maculifrons (Buysson); the western yellowjacket, V. pensylvanica (Saussure); a Holarctic species, V. vulgaris; and a recently described eastern yellowjacket species, V.flavopilosa Jacobson (Jacobson et a!. 1978). Vespula germanica is also in the V. vulgaris group, adding a fifth member to the group in North America. Comprehensive treatment of yellowjacket biology may be found in Spradbery (l973a) and Akre et a!. (1980) which provide the basis for the general biology presented below. Later, we concentrate on the biology of V. germanica in North America, pointing out interesting deviations in biology compared to European populations. All northern temperate yellowjacket species possess an annual seasonal cycle. Each species is represented over the winter solely by inseminated queens which independently establish a colony in early May. Colony growth is very slow at first, but the worker population gradually increases and colonies reach their developmental peak by mid to late summer. Associated with this developmental peak of the annual cycle, workers shift from building small cells to constructing special large cells (queen cells) in which reproductives (queens and some males) are reared. Queens are produced until the end of the seasonal cycle, typically late autumn to early winter, and large colonies may produce several hundred to a few thousand new queens. Mating typically occurs away from the parent colonies. Males die soon thereafter while inseminated queens quickly enter protected sites to overwinter. In the parent colonies, the worker force dwindles rapidly and the foundress dies, marking the termination of the seasonal cycle since temperate yellowjacket colonies do not possess secondary reproductives. Throughout much of the summer, yellowjacket work- 438 ESA BULLETIN ers are beneficial predators on a variety of insects including adult flies, moths, caterpillars, beetle larvae, true bugs and leafhoppers, and Orthoptera. In Europe and in the USA (Schmidtrnann 1977), German yellowjacket workers display a propensity for preying on adult muscoid flies, including the stable fly, Stomoxys calcitrans (L.), and the face fly,. Musca autumnalis DeGeer. Predation on adult flies is probably associated with fly abundance in habitats supporting the German yellowjacket. By late summer, however, foraging for sweets increases as does scavenging for meat. This foraging behavior is related to the increasing nutritional demands of the colonies associated with queen rearing, and compounded by a decline in natural prey as the season progresses. Nearctic V. germanica colonies appear to be behaviorally similar to their European counterparts with the notable exception of the nesting site. According to Vol. 26, no. 4,1980 onies may reach larger size more often in the USA than in their native land. Based on estimates of cell utilization established by Spradbery (1973a), the largest V. germanica colony (Frankfort, IN) produced an estimated 23,000 workers prior to switching to queen production in late summer compared to an estimated 17,000 workers in the largest colony reported by Spradbery. As alluded by Morse et aI. (1977), success of V. germanica in North America in part must be related to the structural nest site. Although rigorous study is lacking, the structural nest site appears to offer a number of advantages in comparison with the subterranean site. Incipient yellowjacket colonies are quite vulnerable and the protected structural nest site probably affords a more favorable environment during this critical period. For example, numerous incipient colonies are destroyed by inundation during spring rains, while mature terrestrial colonies are subject to heavy vertebrate predation. The $pradbery (1971), 27 of 30 V. germanica nests in Eng- structural site provides protection against such adversi- land were subterranean, and only 1 was in an outbuilding; no colony was found in an occupied human structure. To date, we know of very few subterranean V. germanica colonies in North America (Menke and Snelling 1975; Keyel 1980). Nearly all other reported German yellowjacket colonies have been from occupied structures or from outbuildings such as barns and sheds. For example, in the Lafayette, IN, area, 42/43 V. germanica colonies found in 1977-80 were inside structures; 1 colony was subterranean. Many more structural yellowjacket colonies were reported but not confirmed as to species (e.g. a pest control operator with a background in social insect biology destroyed nearly 50 structural yellowjacket colonies in Lafayette homes in 1977-78). In comparison, during 1977-78,47 subterranean but only 7 structural eastern yellowjacket (V. maculifrons) colonies were located around Lafayette, IN. The same pattern existed in Ithaca, NY, where during 1977-78, 24 of 26 V. germanica colonies were structural; the other 2 colonies were initiated in railroad ties and later expanded into the soil below. In comparison, of 53 eastern yellowjacket colonies in the Ithaca, NY area, 46 were subterranean, 5 structural and 2 in railroad ties. Propensity for structural nesting by Nearctic V. germanica is probably a result of a behavioral difference among founding queens. Instead of searching for a nest site in soil cavities, Nearctic V. germanica queens apparently search vertical surfaces of structures for potential nest sites. Commonly employed access holes into structures include chinks in mortar, gaps where walls and eaves or where window frames and walls meet, and holes left from electrical conduits. Such access holes lead into common nest sites including wall voids, attics (often in insulation materials), and basements (space between floor and basement drop ceiling). Due to the difficulty of sampling nests from structural sites, few Nearctic V. germanica colonies have been excavated and analyzed. However, of the few colonies sampled in the USA, half of them are larger than the largest colony found by Spradbery (1971) in England (Table I). This suggests that German yellowjacket col- ties. Extended colony duration also is facilitated by the protected structural site. Lastly, the propensity of V. germanica workers to exploit garbage late in the seasonal cycle may facilitate a longer seasonal cycle. Possibility of Perennial Colonies One of the most frequent questions asked about a yellowjacket colony is if it will persist in the same site the following season. Perennial V. germanica colonies are not without precedent as they have occurred in Tasmania (Spradbery 1973b), New Zealand (Perrott 1975), Algeria and Morocco (Vuillaume et al. 1969), and Chile (Jeanne 1980). Authors report second-season colonies of enormous size with a thousand or more functional queens, several hundred thousand workers and nests of nearly a million cells. Very few second-season colonies of other species have been reported in the USA, however, and they are the exception and are largely restricted to areas with mild winters such as California (Duncan 1939) and Florida (Tissot and Robinson 1954; Akre et aI. 1980). However, Spencer (1960) reported a "perennial" V. pensylvanica colony in the attic of a Vancouver, British Columbia house. Otherwise, temperate yellowjacket colonies are inherently limited to a single season. Among temperate yellowjackets, a foundress queen typically dies prior to cessation of colony activity. Since colonies do not possess secondary queens, continuation of a colony would require re-queening. While re-queening of V. germanica colonies in the USA is possible, a major obstacle would have to be overcome; namely, the circumvention of ovarian diapause that is characteristic of newly emerged northern temperate social wasp queens in autumn, and which persists throughout the overwintering period. Spradbery (1973b) postulates that the ability of V. germanica queens produced near the end of the seasonal cycle in Tasmanian colonies to circumvent ovarian diapause (and thus join the parent colony and assume egg-laying) is related to photoperiod. While day length is decreasing during the period of new queen production in both the southern and northern hem- Vol. 26, no. 4, 1980 ESA BULLETIN ispheres, the seasonal cycle is shifted in the southern hemisphere so that in Tasmania duration of the dark period is a few hours shorter. Thus, Spradbery speculates, newly inseminated queens are somehow able to "join" the present colony (or possibly another nearby colony) and then initiate ovarian development. If, indeed, photoperiod differences are as significant to requeening as Spradbery postulates, then re-queening of V. germanica colonies in the USA may be precluded. Unfortunately, we have no explanation for the few reported perennial Vespula colonies in the USA. A further obstacle to re-queening may be associated with mating behavior. Although little is known about Vespine mating behavior, mating probably does not occur or is very rare inside the parent colony between siblings. If new queens leave the parent colony to mate, an orientation flight would be necessary to enable mated queens to return to the parent colony. Alternatively, mated queens would have to discover and somehow join an alien colony. Two points of evidence appear to preclude re-queening in the parent colony. First, dissections of queens collected inside nests excavated in autumn have shown all such queens uninseminated. For example, all 25 queens sampled from a Frankfort, IN, V. germanica colony collected Nov. 2, 1978 had empty spermathecae, including several that appeared to be in the typical overwintering posture inside the nest envelope. Second, Vespula queens leaving parent colonies in autumn typically do not make an orientation flight about the nest entrance, although such behavior has been reported (Spradbery 1973a). To summarize, the possibility of re-queening leading to second season colonies inside structures seems unlikely. More likely is the frequent occurrence of annual colonies remaining active well into winter with persistence being facilitated by favorable environmental conditions inside certain structures. For example, Morse et al. (1977) mentioned late-season active colonies, and we have reports of active structural colonies in midDecember in Washington D.C. (1. Nixon pers. comm.) and in late November-early December in northern Ohio (P. Landolt pees. comm.). Workers of a structural Lafayette, IN, colony were still foraging when the colony was destroyed the day before Thanksgiving. Such colonies, however, will not persist over winter, and (unless re-queened) will not become active the following spring. Abatement of the German YeUowjacket MacDonald et al. (1976) evaluated the status of yellowjacket abatement in the USA and reviewed the salient research; this report is the basis for the discussion below. In summary, there is no effective area-wide abatement technique for the German yellowjacket. Short of the avoidance of outdoor eating in heavily infested areas, we can offer no other ameliorative measure than the practice of strict sanitation to remove attractive, colony supporting foods. This requires tight fitting receptacle lids and regular garbage pickup, and policing of recreational areas. Industries producing quantities of sweet effluents may be forced to alter production tech- 439 niques and/or production schedules to eliminate attractive materials or to produce them only after the annual cycle is completed. The 2 area-wide abatement techniques that have enjoyed varying, but very limited success against I or 2 west coast species have not worked against any eastern yellowjacket species. For example, use of traps baited with artificial attractants has thus far only abated the western yellowjacket, V. pensylvanica, and then on only one occasion under specific conditions in Oregon. In other areas of the west, depletion trapping has not worked and it is totally ineffective against eastern species. In fact, attractant traps do not even serve as a population monitoring method since eastern species are rarely collected, and Perrott (1975) reported attractant trapping was ineffective against V. germanica in New Zealand. Future use of attractants will likely be limited to enhancing meat bait removal by foraging workers as reported by Wagner and Reierson (1969). Surprisingly, however, the basis for the attractancy, or lack thereof, has still not been investigated. Exploitation of the scavenging behavior of V. vulgaris group workers has been accomplished by mixing a slow acting, non-repellent insecticide into an attractive meat such as tuna, hamburger, horsemeat or commercial cat foods. This is an environmentally sound abatement strategy and has effectively abated populations of the western yellowjacket and V. vulgaris in some areas of California. Unfortunately this method has not worked against eastern species and the failure is apparently due to subtleties in foraging behavior. Still, this is a potentially useful strategy, but research is sorely lacking into suitable meat baits. Encouraging is the report by Perrott (1975) that several meat baits are attractive to the German yellowjacket in New Zealand, including freezedried meats such as barracuda. Research related to the foraging behavior of V. germanica is needed in this country, particularly since the biotype established may differ in aspects of behavior other than nest location. Localized yellowjacket abatement is achieved via the destruction of colonies, but even this is complicated when the German yellowjacket is the offender due to the structural nest site. For example, one Lafayette, IN, colony was suspended (totally exposed) at head height from the ceiling of a dark basement and constituted a serious stinging hazard. One particularly insidious aspect of the structural nest site was noted with 3 Lafayette, IN, colonies in 1979. In each case, a homeowner called to report "masses of yellowjackets" chewing through an interior wall and emerging into the home. Apparently restricted in normal downward nest expansion in the structural wall void, worker yellowjackets initiated lateral nest expansion leading them eventually to chew through the wall. In these 3 cases the homeowner had no knowledge of an existing colony. An additional manifestation of undiscovered structural colonies occurred in several homes this autumn in Lafayette, IN. Homeowners called to report "huge yellowjackets suddenly appearing one morning at windows and on curtains". In these cases, numerous newly produced queens and males were found. They apparently repre- 440 ESA BULLETIN sented reproductives emerging from the parent colony in a wall void toward an interior light source instead of to the exterior via the access hole used by workers. Since the above problems can arise during the season, we recommend destroying yellowjacket colonies in structures as soon as located, although destruction of a viable colony will result in eventual decomposition and possibly some structural damage and offensive odor; if possible, removal of such colonies is advisable. Destruction of individual German yellowjacket colonies poses difficulties not typically encountered with aerial and subterranean nesters. Unfortunately for control purposes, the actual nest site in relation to the access hole is quite variable and not predictable. Thus, the nest may be a few centimeters or many meters distant from the access hole. Furthermore, the nest may be deep into an interior wall, along an outside wall, up into an attic, down into a basement wall or situated between a floor and a basement ceiling. For example, one Lafayette, IN, colony used an access hole above a first floor window frame yet the nest was located over 30 meters away in the attic insulation. Choice of an appropriate control method is very important because ineffective control of a structural colony can result in surviving workers finding or making another exit from the wall void or other structural locations. Exact location of a structural nest should be determined prior to deciding on a control measure but this is not always possible because of the cryptic nest site. The access hole into the structure should never be plugged without first correctly applying the proper insecticide. Furthermore, most household insecticides dispensed from spray cans will not penetrate deeply enough into the structural void and will not penetrate the thick protective nest envelope. Several ineffective control efforts by homeowners in the Lafayette, IN, area led to homes filled with displaced yellowjackets that had chewed through interior wallboard walls. The following procedures and materials are recommended. If the colony is located near the access hole, 1% resmethrin applied as an aerosol is effective. The plastic wand of the aerosol generator is inserted into the access hole and the material released for 30-45 seconds, after which the hole should be plugged with steel wool sprinkled with 5% carbaryl (Apicidel) dust (Akre et al. 1980). Resmethrin provides relatively fast knockdown of adult yellowjackets and the dusted steel wool is chewed by workers attempting to escape the wall void and by workers returning to the nest from the outside. However, resmethrin may not always penetrate the nest envelope to kill the queen and developing brood; thus, adults could emerge for several days following treatment (J. Nixon pers. comm.). When the nest is located away from the access hole, around a corner, or when one is unsure of nest location but wishes to insure success, an additional step is advised. Carbaryl dust (5%) should be forcibly blown deep in all possible directions into the wall void (amount varies with the situation) and followed with the resmethrin application mentioned above. Agitated workers will repeatedly track the carbaryl dust into the nest interior Vol. 26, no. 4, 1980 where it will contact the queen and brood, and effect colony control within a few days. This step is essential when the nest is deep into the structure in situations precluding adequate penetration of resmethrin. Application of carbaryl dust only around the entrance probably will not effect control and may result in workers finding or making another exit hole. We trust entomologists will assist in providing information about the necessity for thoughtful and effective control applications (outlined above) when dealing with structural yellowjacket colonies. Experience in rectifying misguided and ineffective control of the German yellowjacket the past 2 years has impressed upon us the need to prevent such failures from occurring in the future. Future Considerations The German yellowjacket will likely be introduced into many more areas around the world, and probably continue its westward march across the USA. Based on the propensity for movement of overwintering queens via commerce, V. germanica may spread saltatorially via urban centers to the western states. Somewhat surprising is the absence of (or undetected) establishment of V. germanica in the southern states. Potential for new establishment throughout this country makes recognition of V. germanica imperative. However, identification of Vespula species, which is based largely on color patterns, is difficult without experience. Difficulties center around separation ofV. germanica from native Nearctic species such as V. maculifrons, V. vulgaris and V. jlavopilosa in the east, and J • FIG. I.-Nest of a Vespula germanica colony in Frankfort, Indiana home attic. The colony was killed with resmethrin Nov. I, 1978, and collected the following day. Most of the visible structure was envelope paper surrounding the 8 brood combs. Vol. 26, no. 4, 1980 Table I.-Location Location Ithaca, NY Ithaca, NY Ithaca, NY Frankfort, IN Lafayette, IN Lafayette, IN England ESA BULLETIN and nest size of V. germanica 441 colonies from the USA and England." Date Aug. 25, 1977 Oct. 10, 1978 Dec. 1978 Nov. 2, 1978 Sep. 14, 1979 Oct. 29, 1979 Ju]y-Oct. ]96] Estimated Nest Size (Cells) Nest Site Wall void Wall void Attic Attic Basement Basement Subterranean 12,850 7,850 18,370 17,810 11,112" 6,963 11,961 (largest) •• Data based on 30 V. gumanica colonies studied by Spradbery (1911); 27 were subterranean and none were inside homes. h Viable colony that had not shifted to quec:n·cell construction; all 11.112 cells were small, and most contained either worker or male pupae, this colony probably would have remained active into December and would have constructed nearly 14,000 cells. V. vulgaris and V. pensylvanica in the west. Well illustrated identification keys for Nearctic Vespula are provided by Alae et al. (1980) and for the V. vulgaris group by Jacobson et al. (1978). Among eastern North America Vespula. the gray nest of V. germanica is easily distinguished from the tan/orange, fragile nest of V. maculifrons. V. vulgaris and V. j1avopilosai however, a few other Vespula species build gray nests, including V. pensylvanica and several less common species. Establishment of the German yellowjacket in urban areas of the USA will eventually bring about a necessity for area-wide abatement. Presently, the most promising potential tool is the development of a poison meat bait program. Any possible success rests with discovering an attractive bait, but this will require research into worker foraging behavior. Success of a New Zealand program based on freeze-dried meat (Perrott 1975) provides encouragement and, hopefully, incentive for similar research in this country. A more novel approach (at least for yellowjackets) might involve the exploitation of the natural chemical compounds that mediate the social biology of colonies. For example, rigorous study is needed into the basis of attractancy of the synthetic compounds (e.g. heptyl butyrate) discovered to be specific for Vespula. We postulate that these attractants simulate natural compounds that are in some way "biologically meaningful" to individuals in the genus Vespula. Enhancement could lead to an effective means of iuring foraging workers away from attractive food sources. Additionally, Vespula queens appear to influence control of colony mates by means of a queen pheromone (Landolt et al. 1977), and it may be possible to develop an "anti-queen pheromone" and somehow disrupt colony cohesion. Research into the chemical ecology of Vespula is in its infancy, but hopefully this fertile area will attract future researchers. Acknowledgment We thank Dr. George Eickwort, Department of Entomology, Cornell University, and Drs. Gary Bennett and Donald Paschke, Department of Entomology, Purdue University for their constructive criticism and suggestions for improving the manuscript. REFERENCES larvae Or eggs. Left alone, CITED Akre, R. E., A. Greene, J. F. MacDonald, P. Landolt, and H. G. Davis. 1980. 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Wasps: An Account of the Biology and Natural History of Solitary and Social Wasps. Univ. Wash. Press, Seattle 408 pp. Vol. 26, no. 4, 1980 Spradbery, J. P. 1973b. The European social wasp, Paravespula germanica (F.) (Hymenoptera: Vespidae) in Tasmania. Australia. Proc. VII Int. Congr. ruSSI pp. 37580. Thomas, C. R. 1960. The European wasp (Vespula germanica Fab.) in New Zealand. Inf. Ser. Dept. Sci. Ind. Res. New Zealand. 27:1- 74. Tissot, A. N. and F. A. Robinson. 1954. Some unusual insect nests. Florida Entomol. 37:73-92. Vuillaume, M., J. Schwander, and C. Roland, 1969. Note preliminaire sur I'existence de colonies perenees et polygynes de Paravespula germanica. C. R. Acad. Sci. Ser. D. 269:2371-2. Wagner, R. E. and D. A. Reierson. 1969. Yellow Jacket control by baiting. I. Influence of toxicants and attractants on bait acceptance. J. Econ. Entomol. 62: 1192- 7. AT LASTA Practical, Comprehensive Slide Series Covering the PRINCIPLES OF ENTOMOLOGY! THE LEG Instructors of Entomology are constantly searching for highquality visuals and similar teaching software. In response to this need, the Entomological Society of America (ESA) is pleased to offer the PRINCIPLES OF ENTOMOLOGY program. The program consists of sl ides, tapes, and workbooks carefu Ily designed to a id in the teaching of entomology. These valuable materials are available in various sets. The self-contained Audio-Tutorial (A- T) Sets can be used to supplement or replace entire lecture courses. The Slide Sets and/or Workbooks can be purchased and used independently of the tapes to enhance instruction at any level. coxa THE LEG Components of the PRINCIPLES OF ENTOMOLOGY Program SLIDES - Entomological vocabularies, structures, concepts, and principles are all communicated visually on 35mm, full-colorslides. All photographs and artwork are new and original. Over1,100slides are organized into 20 modules consisting of 40 to 70 slides each. GENERAL ENTOMOLOGY (545 slides) trochanter THE LEG SET INSECT MANAGEMENT SET (556 slides) trochanter PRINCIPLES OF ENTOMOLOGY SET (1101 slides) WORKBOOKS - The PRINCIPLES OF ENTOMOLOGY STUDY GUIDE provides the student with a unique kind of written resource material. It presents a concise outline of required information, clearly stated performance objectives, study questions and answers, and technical vocabulary needed to understand basic entomological concepts. This is the perfect study manual for students in any Introductory Entomology course. The PRINCIPLES OF ENTOMOLOGY TEXT is the complete script of the taped narration. tibia TAPES - Narrated by a professional broadcastjourna/ist, these 30to 45-minute cassette tapes provide self-paced instruction for students at all learning levels. Each tape follows a particular slide module and includes audible slide cues. The tapes make it easy to set up individualized review sessions and they afford foreign students a better means to cope with the language barrier. The Authors: Professional Entomologists Ellis Matheny and Daniel Minnick have long been involved in researching innovative instructional methods and producing materials for use in teaching. They developed the successful "open laboratory" mode of learning in the General Entomology course at the University of Florida, Gainesville, and have published papers on innovative instruction and curricula. Dr. Minnick is currently the chairman of the ESA Special Committee on Education. HOLOMETABOLOUS nd 2 LIFECYCLE ~-........... instar /' larva 4l/!DZO( 3rd instar larva ,stinstar .' larva <JlIl!l!>a_oegg_ (complete rI\ ~) " pupa " metamorphosis) 'adult Order the Set That's Best for You at SPECIAL PRE-PUBLICATION SET PRICES!!** SPECIAL PRICE·· CONTENTS AUDIO-TUTORIAL A. General Entomology Set B. Insect Management Set 545 slides, 10 cassettes, Principles of Entomology Study Guide and Principles of Entomology Text $270/set 556 Slides, 10 cassettes, Principles of Entomology Study Guide and Principles of Entomology Text $270/set 1,101 slides, 20 cassettes, Principles of Entomology Study Guide $435/set (SAVE $105!!) C. Principles of Entomology Program (contains set A and set B) and Principles of Entomology Text SLIDE SERIES D. General Entomology E. Insect Management 545 slides and Principles of Entomology Text $215/set 556 slides and Principles of Entomology Text $215/set 1,101 slides and Principles of Entomology Text $350/set (SAVE $ 80!!) Slides Slides F. Principles of Entomology Slides (contains set D and set E) G. Principle of Entomology 1 Book, approx. 175 pages $12.00 each (10 or more $10.00 each) Study Guide ** These special pre-publication valid until March 1st, 1981 ORDERING INSTRUC-r10NS prices are only MAIL ORDER FORM TO: • ESA pays all postage and handling ESA A- T PROGRAM • Materials will not be sent until payment is received 4603 CALVERT ROAD • OFFER GOOD IN U.S.A. ONLY COLLEGE PARK, MD. 20740 r-----------------------------------------------------------------------------------Please send the following Teaching Sets: SET QUANTITY Entomology BILL TO: _ PURCHASE ORDER NUMBER _ COST A. B. C. D. SHIP TO: _ E. F. G. Shipping & Handling TOTAL COST FREE ""Expected Date of Publication is March 1st, 1981 ~------------------------------------ ----------------------------------------------~ I