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Marion Murray, our IPM specialist at Utah State university explains this about some wasps. The European paper wasp and other wasp populations have gone down in many areas of the Intermountain West.
Dr. Whitney Cranshaw, Extension entomology specialist for Colorado State University explains.
"And an insect prediction. This will not be a good year for western yellowjackets, at least in areas where there has been the repeated rainfall over the past month or so. The prolonged cool spring weather would work against successful establishment of yellowjacket nests by the overwintered queens.
Furthermore, it shortens the available time for colonies to develop before they implode in September, so colony size will not get very big. And the repeated rainfall events during the early colony establishment period should also work to destroy many incipient colonies."
Uninvited guests at picnics or hiding in the back garden are not very friendly. Bees and wasps appear in many places but don't make themselves popular. They are a serious nuisance in late summer when foraging at barbecues and garbage cans.
Overall, these insects are valuable as pollinators and predators of other insects, so indiscriminate control is neither warranted nor recommended. Unfortunately, they change from nectar-feeders to meat-feeders and visit our picnics.
Bees and wasps cause different problems and require varied controls. Paper wasps, including yellow jackets and hornets, are social insects and produce new nests each spring. A single female queen starts paper nests in the fall. The colony grows from one to literally hundreds of wasps before the season is over. The large paper nests are abandoned in the fall and are not used the following year.
The wasps disperse as individuals and seek protection to overwinter. They feed on other insects, particularly caterpillars. Yellow jackets become protein scavengers and cause a nuisance when food is served outdoors. They can produce painful stings but do not leave stingers like honeybees.
Hornets produce large, gray nests in trees, shrubs and on buildings. The bald-faced hornet is a common, stout-bodied, dark-colored insect marked with white stripes.
Other hornets resemble yellow jackets. Even though nests are large, hornets rarely sting people unless the nest is disturbed.
Polistes wasps make paper nests with open cells under the eaves of buildings. They have slender reddish-brown colored bodies marked with yellow. They are all beneficial and do not scavenge garbage. They enter houses in the fall, seeking a place to hibernate, but rarely sting unless disturbed.
Ground-nesting yellow jackets are best controlled with a dust type insecticide that they track to the colony.
Yellow jackets are difficult to control unless the nest is destroyed. They may fly as far as 1,000 yards from the colony, so the nest is often impossible to find. Avoid problems with yellow jackets by keeping garbage or other attractive foods covered.
Hunting wasps include mud daubers, potters wasps and other insect-feeding predators. They hunt prey and feed them to their young in nests constructed from mud, plant stems or holes in the ground. Hunting wasps do not live in colonies, but large numbers may nest together. Solitary hunter wasps look fearsome but only sting if handled and seldom require control. Most can be discouraged by irrigating the nesting area, planting lawn or groundcover.
Honeybees feed on nectar and pollen and do not scavenge garbage. Other large bees include bumblebees and carpenter bees. Both of these are beneficial insects and should be left alone.
Leaf cutter and ground bees make tunnels within plant stems, rotten wood or other holes in constructed buildings. Young bees develop in the tunnels and are fed pollen and nectar by adults. Solitary bees do not form colonies but nest together in small areas. The bees do not sting unless handled.
Leaf cutter bees commonly cut a circle smaller than a dime from the leaves. In my garden, the two favorite targets are roses and Virginia creeper, although they attack other plants. As they, too, are pollinators, I tolerate the damage and do not attempt to control them in any way.
Since bees and wasps are beneficial, we only worry when they pose a risk to us or our picnics. The best solution, if you find a nest, is to wait until it is abandoned in the fall. Active colonies can be destroyed with insecticides if they cause problems. Apply insecticide during the late evening when wasps do not readily fly Wasps are less likely to attack people wearing light-colored clothing, and they do not see red light. If you need a flashlight to go on your wasp hunt, cover the lens with red cellophane. Direct insecticide applications at the nest entrance. One application should destroy the colony, although new wasps hatch for several days after the application.
Even though bees and wasps may interfere with your picnic, their wholesale destruction is not recommended. Various alternatives to sprays include traps and baits available at local nurseries. Sanitation is important to control these pests. Remember their beneficial functions, and they become easier to tolerate as they attack your hamburgers at the backyard barbecue.
Written by: Larry A. Sagers Extension Horticulture Specialist Utah Stated University Thanksgiving Point Office
