Vespidae: Paper Wasps, Yellowjackets, Hornets and Potter Wasps

Biology

Wasps in the family Vespidae are the most dominant generalist pollinators. The social vespid wasps are familiar to most home gardeners and despite their fearsome reputation, most provide valuable pollination and pest control services. These are the creatures most people think of when they hear the word ‘wasp’. Native paper wasps live in small groups of 6-20 in papery nests hanging from stalks under eaves or from branches in bushes and trees. These wasps search plants for caterpillars, beetle larvae and other suitable prey that are chewed, then fed to the larvae in the nest. Vespid wasps also frequently visit flowers for nectar. Unless paper wasp nests are in ‘high-traffic’ areas like a doorway, paper wasps usually do not sting people. If you leave them alone, they will leave you alone. However, an aggressive, introduced paper wasp species, the European paper wasp (Polistes dominula), has recently spread to the Pacific Northwest and perhaps should be discouraged in gardens by removing their nests (during winter). It is recognizable by being the only paper wasp with bright orange antennae.

The Golden Paper Wasp (Polistes aurifer) is a striking native species distinguished by its golden yellow color, primarily on the head, abdomen, antennae, legs and wings.  It is common in the west and active from April to October.  Queens begin forming nests from wood and live plant fibers in the spring.  Nests are a single paper-like comb of open hexagonal cells, oriented downwards and can contain up to 200 cells with 20-30 adult wasps.  Golden paper wasp nests are relatively small and typically found in high, sheltered locations.  These wasps are not very aggressive, but will sting if handled or if the nest is disturbed.

Yellowjackets and Hornets are often more aggressive than paper wasps especially in late summer and fall, and should be treated with respect. At this time, the colony queen is dead and there are no more developing larvae to feed, so the workers stop gathering high protein food and start homing in on sugar sources, usually making a nuisance of themselves. There are three common species of Yellowjacket in Washington, the introduced German Yellowjacket (Vespula germanica), the native Western Yellowjacket (Vespula pensylvanica) and the native Aerial Yellowjacket (Dolichovespula arenaria). All have relatively stout bodies with distinct yellow and black banded coloration, with minor differences in patterning. When threatened, these social vespids will defend their nests, inflicting painful stings. This habit along with their preference for scavenging food and being attracted to sugary soft drinks, makes them very familiar and annoying to people. However, they are common visitors to a wide range of flowers and undoubtedly play a significant role in pollination. The nests of yellowjackets are located below ground or behind walls and may contain thousands of wasps. The Bald-faced hornet (Dolichovespula maculata) is technically a yellowjacket, not a hornet and can often be found visiting flowers especially in late summer. These wasps build a large circular hanging nest which they aggressively defend. This species is distinguished from other yellowjackets by being black and white.

Potter and Mason wasps are solitary vespids that build a brood chamber, with mud or sand usually in pre-existing cavities, and fill it with caterpillars (or sometimes with pollen and nectar) as food for their own larvae.  Potter wasps forage commonly on many kinds of flowers, feeding on nectar and transferring pollen as they go.  Most species are black or brown with yellow or white markings.  Potter and Mason wasps make up the majority of species in the Vespidae family.

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