🐝 Order Hymenoptera

Hymenoptera is one of the most agriculturally important insect orders because it includes parasitoids, predators, pollinators, ants, bees, and social wasps. The order is also easy to recognize by its membranous wings, hamuli-based wing coupling, and major role in biological control and pollination.

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Meaning and General Characters of Hymenoptera

• Hymen means membrane
• ptera means wings

Common representatives are ichneumon flies, ants, bees, and wasps.

General characters:

• mouthparts mainly adapted for chewing
• mandibles strongly developed
• in bees, labium and maxillae form a lapping tongue
• thorax specialized for flight
• pronotum collar-like, mesothorax enlarged, metathorax small
• wings stiff and membranous, with reduced venation
• forewings larger than hindwings
• wing coupling occurs through hooklets called hamuli
• abdomen basally constricted in many forms
• first abdominal segment forms the propodeum and is fused with metathorax
• second segment forms the pedicel, with the rest making the gaster or metasoma
• ovipositor always present in females and may be modified for oviposition, piercing, sawing, or stinging
• metamorphosis complete
• larvae usually apodous and eucephalous, though some are eruciform
• pupa exarate, often enclosed in a silken cocoon
• sex determination commonly haplodiploid: fertilized eggs produce females and unfertilized eggs produce males

Hamuli, propodeum, pedicel, ovipositor modification, and haplodiploid sex determination are classic identifying and exam-relevant features of Hymenoptera.

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Symphyta and Apocrita

Hymenoptera is divided into two suborders:

1. Symphyta
2. Apocrita

Character	Symphyta	Apocrita
Abdominal attachment	Broadly joined to thorax	Abdomen petiolated
Larva	Eruciform, caterpillar-like	Grub-like, usually apodous and eucephalous
Stemmata	Present	Absent
Ovipositor use	Often for sawing plant tissue	Often for stinging, parasitism, or specialized oviposition

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Suborder Symphyta

Tenthredinidae

Sawflies are wasp-like insects with:

• abdomen broadly joined to thorax
• saw-toothed ovipositor suited for slicing plant tissue
• larvae generally eruciform and plant-feeding

They are mainly important as defoliators and plant feeders.

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Suborder Apocrita: Parasitoid Families

Ichneumonidae

• adults usually diurnal and flower-visiting
• trochanter two-segmented; hind femur with trochantellus
• forewing with two recurrent veins
• important parasitoids

Braconidae

• small, stout-bodied wasps
• forewing with one recurrent vein
• petiole not curved or expanded apically
• important parasitoids of agricultural pests

Bethylidae

• ant-like, black wasps
• females of many species wingless
• Parasierola nephantidis is a larval parasitoid of coconut black-headed caterpillar

Chalcididae

• small to medium-sized insects
• hind coxae much larger than fore coxae
• hind tibial spurs larger than middle tibial spurs

Eulophidae

• minute pupal parasitoids
• forewing narrow with pubescence on wing lamina
• wing hairs not arranged in rows

Trichogrammatidae

• extremely small insects, about 0.3-1.0 mm
• tarsi three-segmented
• forewing broad with pubescence in rows
• important egg parasitoids used in biological control

Evaniidae

• called ensign wasps
• petiole long and abrupt
• gaster short, compressed, and flag-like

Agaonidae

• fig wasps
• male apterous, female winged
• female with long ovipositor

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Other Apocritan Families

Vespidae

• includes yellow jackets and hornets
• lateral pronotal extension reaches wing insertion and does not form rounded lobes
• abdomen usually conical

Sphecidae

• thread-waisted wasps, digger wasps, and mud daubers
• pronotal extensions form rounded lobes
• petiole slender
• nests made of mud or dug in soil
• prey insects or spiders are provisioned for larvae

Formicidae

• ants are widespread social insects
• antennae geniculate
• mandibles well developed
• strong caste organization and social life

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Bee Families

Apidae

• includes honey bees
• body covered with branching or plumose hairs
• mouthparts chewing and lapping
• mandibles used in wax handling and comb building
• major pollinators and honey producers

Megachilidae

• leaf-cutter bees
• solitary bees
• mandibles sharp and scissor-like
• pollen-collecting hairs (scopa) present on ventral side of abdomen

Xylocopidae

• carpenter bees
• large and robust
• abdominal dorsum bare
• pollen baskets absent on hind legs, but brushes of hairs present

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Summary Cheat Sheet

• Hymenoptera includes sawflies, parasitoid wasps, ants, bees, and social wasps.
• Important order characters are membranous wings, hamuli, strong mandibles, ovipositor modification, propodeum, pedicel, and complete metamorphosis.
• The two suborders are Symphyta and Apocrita.
• Symphyta have broadly joined abdomen and often plant-feeding eruciform larvae.
• Apocrita have petiolated abdomen and include many important parasitoids, predators, and social insects.
• Important parasitoid families include Ichneumonidae, Braconidae, Chalcididae, Eulophidae, and Trichogrammatidae.
• Major social and useful families include Formicidae, Apidae, Megachilidae, and Xylocopidae.
• Hymenoptera is one of the most important orders in agriculture because of pollination, biological control, and social insect diversity.

References

2 sources • [1] [2]

[1]

Fundamentals of Entomology

[2]

Insect Morphology and Systematics