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Hymenoptera

The order Hymenoptera includes many familiar insects, such as social wasps, bees, and ants. The most notable groups affecting trees are the foliage-feeding sawflies.

Morphological characteristics of these insects:

General biology and ecology

The Hymenoptera develop by complete metamorphosis (holometabolous development) passing through egg, larval, and pupal stages before becoming adults. The larval stage is the main feeding period, and the larva forms a cocoon in which it pupates. In parasitoid species, the cocoon may be located outside or inside the host. Parasitoid species have legless larvae that resemble maggots or white worms. By contrast, phytophagous larvae, such as sawflies, resemble moth caterpillars, but they have more than five pairs of prolegs without hooks. In most species, the sex is determined by fertilization: a fertilized egg will produce a female, and a nonfertilized egg will produce a male. Most of the species produce one or two generations per year. Some ants can produce up to five generations annually.

The Hymenoptera are highly varied; sawflies (e.g., redheaded pine sawfly and birch leafminer), along with many ants and bees, are plant-feeders, while other ants and most wasps are predators or parasitoids, and some ants make their nests in wood (e.g., black carpenter ant).

Important families in the order Hymenoptera that contain tree pests

Listed below are families from this order found in this database. Species listed within the families are linked to the site’s pest fact sheets.

Argidae

Cynipidae (gall wasps)

Diprionidae (conifer sawflies)

Formicidae (ants)

Pamphiliidae (webspinning and leaf-rolling sawflies)

Siricidae (horntails)

Tenthredinidae (common sawflies)

Xyelidae