By Eddie Dunbar, Entomologist, Oakland, CA

A Sand Wasp – She’s Got Your Back!

 Sand Wasp ( Bembix americanus ) on daisy

When we think of the insects that are “good,” typically only butterflies and honey bees come to mind. However, there are countless unsung insect good deeds that go unnoticed.
Consider the role of the Sand Wasp (Bembix americanus Fabricius). These are large wasps, nearly 1″ long. They have green eyes and an abdomen with grey and black bands. Adults can be seen at flowers sipping nectar.
Yet, these wasps, truly, are the unsung hero of barbecues and picnics all over North America. Were it not for the Sand Wasp we might be up to our eyeballs in flies. Well, maybe not. But they do eat a lot of them!

Females sting pesky flies into paralysis and use their middle legs to transport them to their young in underground nests in sand. These wasps are excellent diggers. Using their spiny legs they can disappear underground in seconds. Burrows are from 6 to 36″ in depth. Larvae in tunnel cells are provisioned with up to 20 pesky flies over a few weeks. The female returns again and again to replenish the supply of fresh meat. When mature, larvae spin a cocoon in the cell, pupate and emerge from underground as adult wasps. Several broods may be reared by a female wasp in a single summer.
So, the next time you are out and about and there are no flies to bug you, think about the Sand Wasp. She’s got your back.