Sphecidae (Thread-Waisted Wasps)

Sphecid Wasps of Martha’s Vineyard

While the thread-waisted wasps of the family Sphecidae are not especially diverse on Martha’s Vineyard, with only a dozen species solidly documented, these insects have an outsized presence. As a group, Sphecids are active and conspicuous, with the flower-visiting habits of adults making them easy to find. And while sizes of course vary, some of our Sphecids, such as the Prionyx atratus that serves as our banner photo above, are truly imposing beasts, among the largest wasps occurring in our region.

Most members of this family are solitary ground-nesters, with each female digging her own burrow, usually in sandy, unvegetated ground. A few species have a penchant for burrowing into the sand between patio bricks. Females provision their nests with paralyzed arthropods, each wasp species specializing in a particular group of prey. Orthoptera and Lepioptera larvae are common prey prefernces among our Sphecid wasps. Adults feed on pollen and nectar from flowers, as well as, Bugguide cheerfully notes, “body fluids of their prey.” Their predatory habitats mean that Sphecids are ecologically important, helping regulating the populations of their prey even as the adult wasps also serve as pollinators.

While all wasps are more or less “wasp-waisted,” with a narrow connection between thorax and abdomen, Sphecids have developed this feature into an art form. The narrow tube connecting these body segments is always prominent on a Sphecide when it is seen from an appropriate angle, and in some species, the narrow connector is unbelievably long. Many of our Sphecid species either have bright colors or are irridescent, making them beautiful insects.

Our checklist is compiled primarity from “research-grade” observations in the iNaturalist community science platform. We have included one taxon as “Ammophila cf. nigricans;” while no observations of A. nigricans have been confirmed to research grade, a small Ammophila with black wings appears to us to be this species, or something very similar; in any case, it is clearly neither of two Ammophila species that have been confirmed. In the genus Ammophila especially, but in several other of our genera as well, species-level identification from photographs is challenging. Many observations in iNaturalist linger at the genus level. We should caution observers that the artificial intelligence in iNaturalist tends to over-diagnose some Sphecid species, A. procera in particular. Observers should not be bashful about entering observations at the genus level unless diagnostic traits are truly visible to support a species-level identification.

Sphecids are not especially numerous on Martha’s Vineyard, with fewer than 400 observations in INaturalist at the time this account was written in August 2026. But conspicuousness makes thread-waisted wasps easy and fun to find and observe. It can safely be assumed that our checklist is incomplete, and we hope that future observations and perhaps advances in field identification will allow our modest species count to grow in the future.

Matt Pelikan, August 6, 2026