Despite being called the tree wasp, it builds both aerial and underground paper nests, and can be found in rural and urban habitats.

[4] Tree wasps carry out worker policing and have a haplodiploid sex-determination system; this results in a high level of relatedness within the colony.

Worker wasps typically forage for other insects, the nectar of plants, and wood to digest for nest construction.

[11] D. sylvestris can be found throughout Western Europe and across central Asia to China, and it has also been sighted in northern Africa.

The distance between mandible and lower edge of the compound eye (oculo-malar space) is the same or longer than width of antennal scape.

[4] 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.

[15] About 40 worker eggs are produced in the nest at this stage, but some do not mature fully due to limitations in resources provided by the queen.

Around this time, construction of large cells that house the rearing process of queens and more males begins.

The social structure of the nest now collapses and the workers that remain typically die soon due to starvation or old age.

Those trying to catch flies move quickly from one flower head to the next and pounce on prey when it is found.

Foraging takes place from roughly sunrise to sunset of each day in order to keep up with the resources needed for the colony.

[7] Nests of eusocial Hymenoptera including D. sylvestris often have conflict between workers and the queen over production of male eggs.

In nests of tree wasps about half of the male eggs are worker produced so there is the potential for a high level of worker-queen conflict.

It is important to note that workers almost never acted aggressively towards the queen or tried to prevent her from laying eggs.

This value was calculated by analysis at 3 DNA microsatellite loci which allowed the researchers to determine if males were queens’ or workers’ sons.

[5] This high level of relatedness between wasps in the nest is likely what explains the eusocial behaviour in this species.

[16] The diet of D. sylvestris larvae was determined based on close analysis of larval pellets and observation.

Queens were also observed feeding larvae nectar from flowers one drop at a time by putting her tongue and their mouths together.

Nectar seems to be a very important part of the larval diet as both queen and workers took more trips and more time collecting it than either insects or pulp for the nests.

In particular, the fungus Paecilomyces farinosus and the mermithid roundworm, Pheromermis pachysoma are known to parasitise the tree wasp.

[2][8] P. farinosus most often infects wasps and nests after death and therefore does not majorly influence the health of the colony.

[8][18] However, this is not likely to have a major impact on the colony since most worker eggs are policed and the queens typically only have a single mate.

[2] This is mostly due to the fact that this species of wasp does not like to enter buildings and is not interested in the types of food that are consumed by humans.