BIOLOGY AND BEHAVIOR Several different wasps, hornets, and bees are found in Utah and the majority are highly beneficial habits. Bees, such as the honeybee and leaf-cutter bee are essential to the pollination of many crops and native plants. Most wasps and hornets are predators of pest insects, feeding them to their developing young. Problems with these insects occur when nests are located near high traffic areas or in buildings. Late summer foraging by yellow jacket wasps can be a serious nuisance problem for outdoor restaurants and other areas where food is served outdoors. Also, wasps and hornets may enter homes and buildings during fall in search of overwintering shelter.
Social Wasps and Hornets Almost all nuisance problems involve social wasps within or adjacent to structures. Social wasps include yellow jackets, European paper wasps, and others. These insects produce new paper colonies or nests each year. Those produced by yellow jackets and European paper wasps are usually located under eves of structures, in holes, or in wall voids. Bald face hornets make large paper nests among tree branches. Fertilized females overwinter in protected areas, including buildings, and begin to build nests in the spring. As the season progresses, more workers are present to help with colony development, and nests rapidly increase in size. By late summer colonies may house hundreds of insects. At this time, the colony starts to break up and many of the large females leave.
Following several hard frosts the nests are completely abandoned. Nests are not reused the following year. Social wasps feed their young protein rich foods, mainly insects. Late in the season, food preferences switch to include more sugary materials and they are attracted to soft drinks, syrup, and other materials. During this period, they can be extremely annoying. Almost all stings involve social wasps and hornets.
SOCIAL WASP CONTROL METHODS Destruction of wasp and hornet colonies is fairly easy if the nest can be located. Insecticide dusts are usually most effective for ground nesting yellow jackets, since dust is readily tracked into the colony. Aerial nests are best controlled with use of directed sprays forced into the opening. It is best to use an aerosol formulation that includes a fast acting insecticide such as pyrethrins to knock the insects down, combined with a more persistent insecticide. Colonies often are not completely killed for at least a week after application, since developing wasps and hornets remaining in rearing cells continue to emerge for several days. Early in the morning or in the evening wasp and hornet activity is reduced and this is the safest time to treat their colonies.
Light colored protective clothing is best to avoid stings. In some cases it is safer to wait out wasp and hornets infestations. Colonies are abandoned at the end of the season and if the insects are not too much of a nuisance, problems can be resolved without treatment.
Solitary Wasps Several wasps do not produce a social colony and instead individually rear their young in nests of mud or in tunnels underground. These are hunting wasps that collect spiders, cicadas, caterpillars, and other prey for their young. Many are highly beneficial. Although the solitary wasps sometimes appear rather fearsome, they rarely sting, and their sting is less painful than the social wasps.
SOLITARY WASPS CONTROL METHODS If necessary, colonies of mud nesting species can be controlled simply by pulling down nests. Residual insecticide sprays can also prevent wasps from nesting.
Honeybees Unlike the social wasps and hornets, honeybees form a semi-permanent colony. Nests are constructed of wax and most colonies are maintained by beekeepers. Honeybees feed on nectar and pollen, which they feed their young and use to produce products such as honey and beeswax. Honeybees also may collect water to cool the hive and plant sap to help seal cracks.
Periodically, overcrowded colonies form swarms that leave the hive. The swarms rest temporarily on a tree or shrub while scout bees search for a nesting cavity. Althoughthe swarms are very striking, the bees are very docile at this time. Most beekeepers are willing to collect honeybees in a swarm.
HONEY BEE CONTROL METHODS Problems with honeybees occur when swarming bees find a building wall opening and construct nests in buildings. These nests can sometimes get very large over several years and the removal becomes difficult. Although colonies can be relatively easily killed with insecticides, the wax, honeybee debris, and other hive debris remain behind. The wax can melt with high temperatures and old colonies attract rodents and other pests. As a result, the old colony must be removed, which can require tearing out parts of the wall. This can be costly due to the costs associated with an apiarist removing the hive and hiring a contractor to repair any damage associated with removing the hive.