Trypoxylon lactitarse

Taxonomy

Trypoxylon are square-headed wasps in the family Crabronidae. Trypoxylon is a very diverse genus with 634 species distributed worldwide. At the Minnesota Bee Atlas, we have come across at least three species of palearctic Trypoxylon in our observations. One of those species is the larger and easier-to-identify Trypoxylon lactitarse.

Description

Trypoxylon lactitarse are one of the larger species of Trypoxylon with an average length of around 20mm. Like all Trypoxylon wasps, they have long abdomens that arc down and are wider at the tip than the base. T. lactitarse can often be confused with the similar looking species T. politum. However, T. lactitarse can be set apart from other species by its shining black body with pale hairs on the thorax and hind tarsi that are partly white. T. lactitarse are also only about half as large as T. politum.

Nest Structure

Trypoxylon lactitarse build their nests in cavities left behind by other insects or animals. They have also been shown to nest in larger hollow stems and even openings such as keyholes. In our case, they nested in our bee blocks. Unlike T. politum which build free-standing “pipe-organ” shaped nests out of mud, T. lactitarse only uses mud to create cell partitions. They provision their nests with parasitized spiders.

Hole Sizes

No information at this time 

Voltinism

This species appears to be bivoltine in Minnesota.

Activity

Trypoxylon lactitarse are most active in Minnesota from June to August.

References

Coville, R. E. 1981. Wasps of the Genus Trypoxylon Subgenus Trypargilum in North America: Hymenoptera, Sphecidae, 1st ed. University of California Press, Oakland.

Sandhouse, G. A. 1940. A review of the Nearctic wasps of the genus Trypoxylon (Hymenoptera: Sphecidae). The American Midland Naturalist, 24(1), 133-176.