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General Entomology EEB 286
University of Connecticut
Fall 2006
Hymenoptera
Page 1
HYMENOPTERA
NAME ORIGIN: Gk. hymen – membrane; pteron – a wing.
INTRODUCTION: Often considered the most unique of the endopterygota (i.e. they are so modified that their
sister lineage is unclear). There may be over 400,000 species in the world. Hymenoptera is the largest insect order in
North America with 36,000 recognized species. An estimated 50,000-100,000 North American species await
description. Hymenopterists claim that the majority of insects beneficial to humans are members of the order
Hymenoptera, which may be true due to the great number of pollinating and entomophagous species. The family
Formicidae (ants) is one of the ecologically most significant lineages of the hexapods. In tropical ecosystems they
are thought to make up to 25% of all animal biomass.
RECOGNITION:
Larvae:
• head usually well developed
• eyes simple (one stemma)
• abdominal prolegs if present lack crochets
• thoracic legs may be missing
• in suborder Symphyta larvae similar in
appearance and behavior to caterpillars, but
differ in having prolegs beginning on abdominal
segment 2 and continuing to last segment; in
lepidopteran larvae prolegs usually found on A3A6 and A10
• larvae of suborder Apocrita are usually hidden in
nests, hosts, or otherwise concealed
Adults:
• hindwings usually much smaller than forewings
and attached to forewings by row of small hooks
(hamuli), making it difficult to differentiate hindfrom forewings
• often constriction (petiole) between abdominal
segments 1 and 2
• haplodiploid sex determination (haploid males
resulting from unfertilized eggs, diploid females
from fertilized eggs) almost universal in
Hymenoptera
HABITATS: Four major life patterns exist: (1) the primarily phytophagous Symphyta, (2) the parasitic or
gall-making Apocrita, (3) the non-social Apocrita whose larvae are fed prey or pollen captured by the
mother, and (4) the social Apocrita. Virtually all apocritan larvae are provided with a food resource and do not
forage. Hymenoptera are generally diurnal or crepuscular, with few nocturnal species. Adults are often found
among vegetation, particularly flowers, or among leaf litter (e.g. ants). Many build nests or burrows in the ground.
Social species usually create large nests that may be well defended by stinging workers.
COLLECTING: Virtually every collecting technique (except aquatic methods) will capture Hymenoptera. Some
parasitoid species are best captured by rearing from hosts. Yellow pan traps, flight intercept and Malaise traps
capture many species that are rarely caught by hand. All Hymenoptera can be mounted on pins or points. If possible,
wings should be positioned to allow viewing of wing veins. The vast majority of Hymenoptera species are parasitoid
wasps under 5mm in length that require pointing.
TAXONOMY: There are two suborders: the less derived Symphyta whose larvae resemble lepidopteran
caterpillars and whose adults have the thorax broadly joined to the abdomen (lacking a constriction), and the
Apocrita, whose larvae lack prolegs and whose adults have a constriction at the base of the abdomen. The
Symphyta contains only a small percentage of hymenopteran species diversity. Within the Apocrita there are two
major groups: the Parasitica, which includes the parasitic and gall-making species, and the Aculeata, which includes
the usually stinging species and the social lineages (bees, ants and wasps).
General Entomology EEB 286
University of Connecticut
Fall 2006
Hymenoptera
Page 2
Suborder: Symphyta (sawflies, horntails, and wood wasps)
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base of abdomen broadly joined to thorax
hindwing with 3 basal cells
forewing with 1-3 marginal cells and nearly always with accessory vein
trochanter 2-segmented
larva caterpillar-like, phytophagous (mostly)
females without sting
Family: Tenthredinidae (common sawflies)
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antenna threadlike, usually 9-segmented
forewings with 1 or 2 marginal cells and without intercostal vein
body 5-20 mm; coloration variable
larvae: most feeding externally on leaves; a few leaf miners or gall makers
some species damaging cultivated plants and forest trees
largest family of sawflies, with about 800 N. American species
Family: Siricidae (horntails)
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pronotum wider than long and narrowed along
midline
body large, 25-35 mm, usually distinctly elongate
front tibia with single apical spur
larvae wood borers in trees (prey of Megarhyssa)
19 NA species
Suborder: Apocrita (parasitic wasps, ants, wasps, and bees)
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base of abdomen constricted, sometimes distinctly stalked
hindwings with no more than 2 basal cells
thorax comprising of 4 segments (4th segment, propodeum, being 1st
abdominal segment)
wings without accessory vein
venation in many groups greatly reduced; many forms completely
wingless
larvae commonly parasitic on other insects or forming galls on
plants
ovipositor often retractable and modified into sting
Family: Braconidae (braconids)
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antenna usually long, with more than 16
segments
1st recurrent vein in forewings present or
absent; 2nd recurrent vein (more distal)
always absent
body small, 2-15 mm, usually brownish or
black
larvae parasitoids; many pupating in silken
cocoons on outside of host’s body
many species important in biological control
a few large nocturnal species have mild sting
more than 1900 NA species
General Entomology EEB 286
University of Connecticut
Fall 2006
Hymenoptera
Page 3
Family: Ichneumonidae (ichneumons)
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antenna usually at least half as long as body; with 16 or more
segments
two recurrent veins present
body slender, wasp-like, 3-40 mm
ovipositor usually very long, sometimes longer than body; most
species non-stinging
coloration variable, many species with bright black and yellow pattern
parasitoids of other insects, many of value in control of insect pests
one of largest family of insects, with more than 3300 species in N.
America
Superfamily: Chalcidoidea
antenna elbowed and usually short, with 5-13 segments
wing venation greatly reduced
mostly 5 mm or less
pronotum in profile somewhat squarish
ovipositor usually short
most black, blue-black, or green, often metallic
many species parasitoids or hyperparasitoids – parasitoids of parasitoids, e.g.
tachinid flies or ichneumons
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Family: Cynipidae (cynipids, gall wasps)
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scutellum with dorsal O-shaped elevation
body small, 2-8 mm
thorax rough (Cynipinae), abdomen oval and shining
majority of species (all Cynipinae) gall makers or living in galls made by other
organisms
shape and position of gall on plant usually species specific and allowing for
easier identification than wasps themselves
some Cynipidae (Eucoilinae and Charipinae) parasitic on Diptera or
hyperparasitic on braconids
Family: Chrysididae (cuckoo wasps)
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coloration striking, metallic blue or green, usually with coarse
sculpturing
abdomen with 4 or fewer segments, venter concave
hindwing with distinct lobe at base and without closed cells
body 6-12 mm
last tergum often toothed apically
when disturbed, they often curl into ball but do not sting
larvae parasites or inquilines of wasps or bees