HYMENOPTERA > APOCRITA | Aculeata > Vespidae > Eumeninae

A reasonably large (9-15mm body length), narrow-waisted, predominantly black species with yellow markings on the head and thorax, two large yellow patches on segment S2 and similarly coloured lower abdominal banding.

Eumenes coarctatus is a 'nationally scarce' southern heathland species that is only found in a few suitable locations where there are areas of exposed clay soil, access to water, together with a good growth of heather or gorse on which the mud pots can be constructed, and a plentiful supply of caterpillars.

Females are most active from late May to around the middle of September. During this time, they will have mated and built possibly twenty or more pots, each of which may have taken up to three hours to construct. After laying a single egg in the completed nest, she will start hunting for small caterpillars, which are paralysed and stuffed into the pot until it is full. This process alone can often take a couple of days or more as anything up to several dozen may be required. Once she's happy that the pot has been properly provisioned the entrance will be sealed with more wet soil. If the weather is good and there is plenty of food stock the pots can be completed much quicker, but if it's wet and/or caterpillars are hard to find, the eggs may start hatching before it's complete and the larvae will most probably die. Typically though, the pots will be successful and the wasp will be off to start the process all over again. The eggs would normally hatch after about three days with the larvae feeding off the caterpillars. Those that hatch early may pupate and emerge in the same year, but otherwise they will overwinter to the following April or May.

Despite searching, I've only seen the species once and was not able to observe any of the above behaviour. It would be nice to see but, until I can, my knowledge is very much limited to what I've read. Unfortunately, some of the known areas where these wasps could regularly be seen have been negatively affected by the introduction of cattle during the summer months that graze and trample everything in their path, thereby destroying the pots before the new wasps have emerged.