Dolichovespula: A Brief Discussion

Dolichovespula is a genus of wasps within the family Vespidae, which contains most of the social wasps commonly observed by average persons.1 Specifically, Dolichovespulans are members of the Vespinae subfamily, which consists of three genera: Vespa (true hornets), Vespula, and Dolichovespula, the latter two of which constitute the group commonly known as “yellowjackets”.2 Indeed, the Dolichovespulans were once considered a subgenus of Vespula itself; however, they were moved to their own family due to a few key differences.3 First - and most importantly - Dolichovespulans have a long “malar space” - that is, the gap between the base of the compound eye and the mandibles. This is in contrast with Vespulans, who have a near-insignificant gap in the same region.4

This fits with the more immediately obvious distinction that Dolichovespulans have overall longer faces than their counterparts, whose heads tend to possess a less pronounced triangular shape (as a matter of fact, it is this detail that gives the Dolichovespulans their name). Last, but certainly not least, is that Dolichovespulans have a far greater proclivity towards building above ground, typically suspended nests than their Vespulan relations. It is for this reason that they are sometimes referred to informally as “aerial yellowjackets,” although there are obviously exceptions to this rule in both directions.  

Like many members of Vespinae, Dolichovespulans are social insects.5 “Queens” begin the construction of gray, ovular nests - usually in open areas such as bushes, trees, or building overhangs - after emerging in Spring from a sort of hibernation. She builds the nest out of wood, specifically the cellulose of dead or dying trees, which she turns into a past by masticating in her jaws and adding her saliva to the pulpy mix.6 For the first “brood” - the first collection of cells in the fledgling nest - the Queen will do all of the foraging and feeding for her offspring. Like all Hymenopterans, Dolichovespulans undergo holometabolism (complete metamorphosis). After the Queen lays her eggs in the tiny paper cells, they quickly hatch into the tiny larvae. In general, wasp larvae are white, almost worm-like creatures with heavily underdeveloped forelimbs and no wings.7 Rather, they possess a fully functional pair of jaws, which they swiftly put to work consuming almost anything given to them. The larvae will molt a few times between emergence and entering the pupal stage, each time growing larger and obtaining more prominent features, although they never lose their basic appearance. Eventually, the larvae complete their growth and will construct a pupal case at the entrance to their cell.

It is during this time that they will “reconstruct” themselves into an adult, forming wings, more pronounced segmentation, longer limbs, and, of most immediate significance for the new worker, her large mandibles. She will use these to chew her way out of the pupal case, after which she will rest and allow her exoskeleton to finish hardening and her wings to dry and unfurl. Once this has happened, she will then be capable of assuming her duties for the nest, which, in this case, involves taking on the foraging roles the Queen had previously done by herself. As the nest grows, Dolichovespulans will build an external paper covering around the nest cells, a habit that they share with other members of their subfamily and is a major factor distinguishing them from the abundant Polistes. The populations of these colonies will vary, but the nests of the North American Dolichovespula maculata generally range in size from two hundred to four hundred workers, with some rare cases being found with over seven hundred individuals.

Relatedly, another curious distinction between Dolichovespula and Vespula stems from the relationship between the queens and the workers themselves. Unlike Vespula, Doliochovespulan queens usually only mate once in their entire lives.8 This results in the worker population being far more closely related to each other than is typical in “yellowjacket” nests. Interestingly, not all Dolichovespulan workers emerge as infertile; some are capable of producing male offspring, something that evidently creates some degree of turmoil within nests between workers and queens, although the queens nonetheless maintain their curious control over the workers throughout (it helps that workers are usually unable to produce more male offspring than the queen).  

Like most Vespids, Dolichovespula are largely carnivorous, feeding heavily on flies, caterpillars, and other wasps. They eventually turn more heavily towards flowers and other significant carbohydrate sources later in the year when their prey become scarcer, which brings them more into contact with humans than is generally appreciated. Regardless, their voracious appetites allow them to serve as a valuable form of pest control, and it is largely for this reason that, unless the nest is built in a potentially dangerous location with relation to humans, it is advised that their nests be left alone (that, and their propensity to defend their homes with venomous stings that react particularly strongly with mammalian nervous systems).  

 

Bibliography: 

1. Family Vespidae. (n.d.). 2003-2024, Iowa State University. https://bugguide.net/node/view/198 
2. Subfamily Vespinae - hornets and yellowjackets. (n.d.). 2003-2024, Iowa State University. https://bugguide.net/node/view/385 
3. Genus Dolichovespula - aerial yellowjackets. (n.d.). 2003-2024, Iowa State University. https://bugguide.net/node/view/12982 
4. Key to Nearctic Vespinae genera. (n.d.). https://cjai.biologicalsurvey.ca/bmc_05/key_vespinae.html 
5. Dolichovespula maculata. (n.d.). Animal Diversity Web. https://animaldiversity.org/accounts/Dolichovespula_maculata/ 
6. Baldfaced Hornet. (n.d.). https://extension.psu.edu/baldfaced-hornet 
7. Michael. (2023, August 8). Stages of wasp larvae development: From egg to adult wasp | PollenPaths. PollenPaths. https://pollenpaths.com/wasp-larvae-stages/ 
8. Wayback machine. (n.d.). https://web.archive.org/web/20190927164617/https://pdfs.semanticscholar.org/37d3/f03ad7939e630a056f3416f35f3f27fa3b23.pdf