Your Labor Day picnic is likely to have an extra visitor or two. These are not invited or even wanted guests. The wasps. The most familiar yellowjacket in Utah is the German yellowjacket. Its nest is usually constructed underground. The spring queen seeks out abandoned rodent burrows to construct her paper nest.
Nests can be found by observing the flight pattern of the yellowjacket. They will land on the ground and disappear! A closer look will reveal a tunnel. Later in the year, the entrance hole will have dirt and pebbles piled around it. This debris is the result of expansion activities in the nest.
Paper wasps are the most common pest we see at picnics. They make small papery nests with as many as 100 cells that face down.
Yellowjackets are smaller than most hornets and wasps. They look fatter and have and are distinctively black and yellow in color.
Yellowjackets, bald-faced hornets and paper wasps are predators. They actively scavenge any source of animal protein including your steak.. They are commonly seen buzzing around garbage as they have a sweet tooth.
Unless wasps, hornets and yellowjackets become a threat, leave them alone. They play an important role in the ecological balance of your garden.
If you must take action do not risk your personal safety these insects. These colonies may be very large (perhaps several hundred individuals), and their location may be difficult to get to. Wear protective clothing. These insects sting and their venom is painful.
If you decide to treat the colony with an insecticide, do it at dusk or dawn when the pests are less active.
"Wasp and Hornet Sprays" do a good job of destroying the colony. Wasp and hornet sprays have a directed stream rather than the mist spray like most aerosol insect sprays. Read and follow all instructions on the pesticide label.
KSL Greenhouse Tip Larry A. Sagers Regional Horticulturist Utah State University Thanksgiving Point Office