Median wasp

Appearance

"D. media" is a medium to large species of wasp around 16–22 millimetres in length with yellow and black stripes on its abdomen. It can be identified by its yellow clypeus with a thin black central line and large areas of yellow behind the eyes and on the ocular sinus. The median wasp also has a shiny black thorax with four yellow spots that are tinted orange or red. Queens are often mistaken for hornets due to their reddish colouration, but can be distinguished by their thoracic spots and deep black color.

Distribution

The median wasp has a Palearctic distribution and is found throughout Europe and temperate regions of Asia all the way east to Japan. It prefers temperate climates and high humidity. This species was identified in the United Kingdom for the first time in 1980 after having spread there from continental Europe. It has also been sighted in New Zealand, but it is not known if the wasp is widespread in the area or if this was an isolated occurrence.

Behavior

It is most common to see this wasp between May and October during its 3.3 month colony cycle. Behaviours of this wasp include nest defense, curling which is believed to function in brood incubation, and gastral vibration which is involved in larval feeding. The median wasp has a halplodiploid sex determination system that results in a high level of relatedness within the colony. This species is not usually aggressive but will sting if they feel their nest is threatened. Most foraging in the nest is done by the workers once the first ones reach adulthood. These workers forage for insects, nectar, and wood for nest construction in temperatures as low as 7 °C. The median wasp is known to be occasionally affected by the fungus "Cordyceps sphecocephala" and the Cricket paralysis virus.

Habitat

"D. media" builds aerial paper nests 1 to 5 metres above ground. These nests are typically found in shrubs, trees, and sometimes under the eaves of buildings. Nests are made of paper that comes from the digestion of wood and are generally 12–23 centimetres wide and 10–30 centimetres tall. Colonies are often found in both urban and rural areas. These wasps prefer to build nests close to the ground where humidity levels are higher as well as in open areas where the nest is subject to large amounts of sunlight.