Stinging Pests

Adult female paper wasps that mate in the fall of the year are capable of over-wintering in the adult stage, in sheltered places such as culverts, standpipes, attics, barns, outhouses, wood piles, garages, or any other structure that affords protection from the harshest elements. All of these over-wintering females are potential new queens, for the nest and social colony. There are no sterile female workers in a paper wasp colony

They are social wasps. If you knock down the nest of the paper wasps they are more than likely to be rebuilt on the very same spot within a few days. Since they are social wasps, they feel an instinct to protect their nest. Because their nest is open it also may be available to predators, and one of the predators these wasps fear is ants. Ants would love to swarm over the nest and drag the big, juicy larvae out of their cells, to take back as food for their own larvae. Nests may house several hundred to several thousand individual cells, depending on the species. Typical nests around homes generally stay in the range of a couple of hundred or less. Paper wasps will over-winter and will reuse and add on to their nests in the following spring.

Only female wasps have a stinger, all of the members of the colony are females, and therefore all of them can sting. Males do not participate, but are created at some period of the colony life for mating only.

One queen will produce 25,000 eggs or more during her lifetime. It is one of the several species that may build its nest in holes in the ground, or will hang aerial nests in trees, shrubs, attics, barns, walls, etc. Sometimes old nests have been built in protected places, such as an attic or between walls, and may be reused and expanded, producing up to 100,000 or more yellow jacket offspring.

Yellow jackets are social hunters living in colonies containing workers, queens, and males. Colonies are annual with only inseminated queens overwintering. Although adults feed primarily on items rich in sugars and carbohydrates (fruits, flower nectar, and tree sap), the larvae feed on proteins (insects, meats, fish, etc.). Adult workers chew and condition the meat fed to the larvae. Larvae in return secrete a sugar material relished by the adults. This exchange is known as trophallaxis. In late summer, foraging workers change their food preference from meats to ripe decaying fruits or scavenge human garbage, sodas, picnics, etc., since larvae in the nest fail to meet requirements as a source of sugar. This is why yellow jackets are known largely as pests that are capable of ruining picnics. Although they lack the pollen-carrying structures of bees, yellow jackets can be minor pollinators when visiting flowers.

Known to be aggressive defenders of their colonies, yellow jackets are otherwise not quick to sting. The sting of a yellow jacket is painful and each insect is capable of delivering multiple stings. Yellow jacket stings may induce severe allergic reactions in some individuals.

Every year, queens that were born and fertilized at the end of the previous season begin a new colony. The queen selects a location for its nest, begins building it, lays a first batch of eggs and feeds this first group of larvae. These become workers and will assume the chore of expanding the nest – done by chewing up wood which is mixed with a starch in their saliva. This mixture is then spread with their mandibles and legs, drying into the paper-like substance that makes up the nest. The workers also guard the nest and feed on nectar, tree sap and fruit pulp. They also capture insects and arthropods, which are chewed up to be fed to the larvae. This continues through summer and into fall. Near the end of summer, or early in the fall, the queen begins to lay eggs which will become drones and new queens. After pupation, these fertile males and females will mate, setting up next year’s cycle of growth. As winter approaches, the hornets die – except any just-fertilized queens. These hibernate underground or in hollow trees until spring. The nest itself is generally abandoned by winter, and will most likely not be reused. When spring arrives, the young queens emerge and the cycle begins again.

The nest of the bald-faced hornet can be found hanging from trees, bushes and buildings. A bald-faced hornet nest can grow to be as large as a basketball within a number of months. As many as 700 workers may live in the nest. Bald-face hornets will sting repeatedly if disturbed. Like other stinging wasps, they can sting repeatedly because the stinger does not become stuck in the skin.

While bald-faced hornets do prey upon other pests and can prove beneficial, their nests should not be permitted to develop near a home. Workers are protective and aggressive when disturbed.

The adults emerge in the spring, mate, and begin construction of their nests which may contain one or more cells. Mud Daubers are solitary wasps. They are predators that capture and sting insects and spiders to provision their nests. The female mud dauber collects spiders which she stings and paralyzes and then places inside the chambers. She then lays an egg on the spiders in each chamber before sealing it off. The larval wasp hatches and feeds on the spiders provided, molting several times. Development takes about 3 weeks. The larva then spin a cocoon and overwinters until the following spring when it pupates. It then transforms to an adult wasp which emerges from its mud chamber.

Mud daubers are rarely aggressive. They are also the main predator of the black and brown widow spiders. Black-and-yellow mud-dauber build a simple, one-cell, urn-shaped nest that is attached to crevices, cracks and corners. Each nest contains one egg. Usually, they clump several nests together and plaster more mud over them. Blue mud-daubers frequently appropriate old nests of black-and-yellow mud-daubers. They carry water to them and recondition them for their own purposes. The two species commonly occupy the same barns, porches, or other nest sites. Adults of both sexes frequently drink flower nectar. To capture a spider, the wasp grabs it and stings it into submission. The venom from the sting does not kill the spider, but paralyzes and preserves it so it can be transported and stored in the nest cell until consumed by the larva.

Adults overwinter in galleries, emerging in the spring to mate. The female prepares a nest by excavating a new site or more frequently by cleaning out and expanding an existing tunnel. After the nest is ready, she places a mass of pollen mixed with nectar in the blind end of the tunnel, lays an egg on it, and builds a partition of chewed wood pulp to form a brood cell. Six to eight brood cells are constructed in each cell. The bee larvae develop on the pollen and emerge as adults 30 to 40 days later, usually in late summer. There is one generation per year.

Carpenter bees are not social insects, i.e., they do not live in nests or colonies like yellow jackets and honey bees. Carpenter bees bore holes into wood to create a tunnel in which to raise their young. They attack decks, siding, landscape timbers, and even lawn furniture. They seem to prefer unpainted wood, but they will also attack painted or stained wood. The initial opening is straight into the wood and is cut in an almost perfect circle. When the hole is about an inch deep, she turns and begins to burrow along the grain. A new gallery may be 6″ long. Older galleries that have been re-used may extend several feet. It takes a female several days to make a 6″ gallery. Entry holes are usually located in well-lit and sheltered areas, such as headers, roof eaves, porch ceilings, fascia boards, decks, doors, and window sills. Soft wood, such as California redwood, cedar, white pine, and poplar is preferred for nest building.

Male carpenter bees are very aggressive, but they have no stinger. Females have a potent stinger, but seldom sting.