07/06/2015
Bug Bug Bug of the day... The Yellow Jacket
Yellow jacket or yellowjacket is the common name in North America for predatory wasps of the genera Vespula and Dolichovespula. Members of these genera are known simply as "wasps" in other English-speaking countries. Most of these are black and yellow like the Eastern yellowjacket Vespula maculifrons and the Saxon wasp Dolichovespula saxonica; some are black and white like the bald-faced hornet, Dolichovespula maculata. Others may have the abdomen background color red instead of black. They can be identified by their distinctive markings, their occurrence only in colonies, and a characteristic, rapid, side-to-side flight pattern prior to landing. All females are capable of stinging. Despite having drawn the fear and loathing of humans, yellow jackets are in fact important predators of pest insects.
Yellow jackets are sometimes mistakenly called "bees" (as in "meat bees"), given that they are similar in size and appearance and both sting, but yellow jackets are actually wasps. They may be confused with other wasps, such as hornets and paper wasps. Polistes dominula, a species of paper wasp, is very frequently misidentified as a yellow jacket. A typical yellow jacket worker is about 12 mm/0.5 in long, with alternating bands on the abdomen; the queen is larger, about 19 mm/0.75 in long (the different patterns on their abdomens help separate various species). Workers are sometimes confused with honey bees, especially when flying in and out of their nests. Yellow jackets, in contrast to honey bees, are not covered with tan-brown dense hair on their bodies, they do not carry pollen, and do not have the flattened hairy hind legs used to carry it.
These species have lance-like stingers with small barbs, and typically sting repeatedly, though occasionally a stinger becomes lodged and pulls free of the wasp's body; the venom, like most bee and wasp venoms, is primarily only dangerous to humans who are allergic or are stung many times. All species have yellow or white on their faces. The mouthparts are well-developed with strong mandibles for capturing and chewing insects, with probosces for sucking nectar, fruit, and other juices. Yellow jackets build nests in trees, shrubs, or in protected places such as inside man-made structures, or in soil cavities, mouse burrows, etc. They build them from wood fiber they chew into a paper-like pulp. Many other insects exhibit protective mimicry of aggressive, stinging yellow jackets; in addition to numerous bees and wasps.
Yellow jackets' closest relatives, the hornets, closely resemble them, but have larger heads, seen especially in the large distance from the eyes to the back of the head.
In 1975, the German yellow jacket (V. germanica) first appeared in Ohio, and has now become the dominant species over the eastern yellowjacket. It is bold and aggressive, and can sting repeatedly and painfully if provoked. It will mark aggressors, and will pursue them if agitated. It is often confused with Polistes dominula, an invasive species in the United States, due to their very similar pattern. The German yellow jacket builds its nests in cavities—not necessarily underground—with the peak worker population in temperate areas between 1000 and 3000 individuals between May and August. Each colony produces several thousand new reproductives after this point through November. The eastern yellow jacket builds its nests underground, also with the peak worker population between 1000 and 3000 individuals, similar to the German yellow jacket. Nests are built entirely of wood fiber and are completely enclosed except for a small entrance at the bottom. The color of the paper is highly dependent on the source of the wood fibers used. The nests contain multiple, horizontal tiers of combs within. Larvae hang within the combs.
In the southeastern United States, where southern yellow jacket (Vespula squamosa) nests may persist through the winter, colony sizes of this species may reach 100,000 adult wasps. The same kind of nest expansion has occurred in Hawaii with the invasive western yellow jacket.
