Yellowjackets and the Danville Summer Backyard

The valley's most dangerous summer pest

Paper wasps under the eaves get noticed, but the real hazard on a Danville lot is the yellowjacket. These aggressive wasps nest hidden, in old rodent burrows and slope banks, in wall voids, and in attic and eave gaps, and they defend the nest fiercely. On the oak-studded, hillside lots common across the San Ramon Valley, there is no shortage of nesting sites.

A colony that starts small in spring can number in the thousands by late summer, which is exactly when a backyard, deck, or pool area becomes dangerous.

Spotting a hidden nest

A steady stream of wasps in and out of one spot, a hole in the ground, a gap in a retaining wall, a crack in the siding, usually means a hidden yellowjacket colony. Late-summer foraging at food, sweet drinks, and trash is another sign the population has grown.

Hidden ground and wall nests are not a DIY job. Disturbing one without the right approach and protective gear provokes the whole colony, and yellowjackets can sting repeatedly.

Safe removal and prevention

A local exterminator identifies the nest and species, then treats and removes it with the proper products and protective gear, treating ground and wall colonies at the entrance so the workers carry it in. Accessible paper wasp nests are knocked down directly.

Because the surrounding open space produces new queens every year, prevention matters: knock down old nests and seal gaps at eaves, vents, and wall penetrations so queens can't re-colonize the same spots next spring. Calling early in the season, when nests are small, is far safer and simpler than waiting for a late-summer colony.

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