Tree Wasp

Dolichovespula sylvestris can reach a length of 11–15 millimetres (0.43–0.59 in) in workers, of 15–19 millimetres (0.59–0.75 in) in queens and of 13–17 millimetres (0.51–0.67 in) in males. This medium-sized species has the typical drawing of black and yellow stripes of many social wasps. The head and the thorax are predominantly black with yellow drawings. The abdomen is black with transverse yellow bands. The wings are slightly brownish. The distance between mandible and lower edge of the compound eye (oculo-malar space) is the same or longer than width of antennal scape. The large eyes are C-shaped, as they have a strong cut in the edge. At the top of the head there are three small ocelli. This species can be identified by its solid yellow face with a single small, central, black dot on the clypeus, a thorax with long lateral hairs, and two posterior yellow spots. This species is less aggressive in comparison to many wasps, but will sting both animals and humans to protect its nest. Nests are made of paper that comes from the digestion of wood, generally dead bark, and measure 10–15 centimetres (3.9–5.9 in) in diameter with an average of 4 combs.

D. sylvestris can be found throughout Western Europe and across central Asia to China, and it has also been sighted in northern Africa. It is not known to live outside of this region of the world. This species of wasp prefers temperate climates. In these regions it can be found in most habitats, including trees and shrubs, hanging from houses, and in the ground. It is often found in both urban and rural areas. Despite being called the tree wasp, D. sylvestris builds both aerial nests in trees and hedges, as well as underground nests. These underground nests are typically built near the ground surface in preexisting holes. All nests appear to need an overhanging structure to suspend from, such as a rock, grass stem, or roof of a house, but the location and type of these structures can vary significantly.

In the colony, the queen is responsible for all of the foraging for the nest until workers mature. This includes foraging for wood to make into pulp for the nest as well as food for the larvae. Most workers begin to help with foraging the day after they emerge from the nest as adults. Almost immediately, they take over all foraging activity for the queen. The behaviour of the workers who forage differs depending on their activity. Those trying to catch flies move quickly from one flower head to the next and pounce on prey when it is found. In comparison, wasps that forage for nectar move slower and spend more time at each flower. Other workers collect pulp from dead wood to use for nest construction. It appears that if the wasp is unable to quickly catch a fly it goes on to collect nectar suggesting one worker does not always collect the same type of material. Different amounts of time are given to each activity with the most time spent gathering fluid, then pulp, and then flies. Foraging takes place from roughly sunrise to sunset of each day in order to keep up with the resources needed for the colony.