Scavenger Wasps

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Summary: Only three or four different yellowjacket wasps account for most of the problems associated with this insect. These "problem yellowjackets" are the scavenger species that make large and threatening nests. The scavenger species also are the ones that bother us at picnics, and similar events, where there is exposed food.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

Scavenger yellowjackets

Of all the yellowjacket wasp species in the world just three or four account for the majority of problems with these otherwise beneficial insects. These species are listed in the table below along with the regions where they are found. Two of the most troublesome species worldwide are the common yellowjacket wasp (Vespula vulgaris) and the German yellowjacket wasp (Vespula germanica). Both are highly invasive pests. The other two troublemakers, the western and eastern yellowjacket wasps, are more regional in occurrence.

The one characteristic that distinguishes pest yellowjackets from non-pest species is that pest species have adopted a scavenger habit wherein they supplement their normal diet of live prey with scavenged (dead) food. This behavior has two consequences: scavenger species make larger nests and foraging worker yellowjackets come into contact with people more often when there is exposed food outdoors.

large yellowjacket wasp nest

aerial yellowjacket wasp nest

Larger, more dangerous wasp nests

There is evidence that the scavenger habit adopted by these few species has allowed them to be more successful ecologically. The scavenger species tend to build larger nests that house many more workers than their predatory cousins. The scavenger habit may also allow these species to spread more rapidly into new geographical regions. The common yellowjacket and the German yellowjacket are rapidly expanding their ranges worldwide.

Contact with people

Scavenger yellowjacket species are also more likely to come into contact, and conflict, with people whenever there is exposed food outdoors. Scavenger wasps are common around garbage, carrion and rotting fruit as well.

How to avoid wasp stings

First, when outdoors cover exposed foods as much as possible. For planned outdoors events such as a wedding or reunion use a baiting/trapping program to reduce the number of foraging wasps in the immediate area of the activity (see How to Use Yellowjacket Traps). Finally, treat known aerial and ground nests to also reduce the number of foraging wasps (see How to Safely Control Wasp Nests).

Where Do The Scavenger Wasps Occur?

common yellowjacket
German yellowjacket
western yellowjacket
eastern yellowjacket
western US, western CAN, Hawaii
south & eastern US, central (mid-western) US

Related Articles

Life History of Yellowjacket Wasps

Yellowjacket Wasp Stings

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