Solitary Wasps Making a Home at Nature Boardwalk
These past few weeks biologists at the Urban Wildlife Institute have been seeing large sphecid wasps (of the Sphecidae family) buzzing around Nature Boardwalk at Lincoln Park Zoo.
While this isn’t the first time this particular family has been spotted at Nature Boardwalk, it is our first sighting of the species above!
Wasps in the Sphecidae family are different from other types of wasps in that they are solitary, meaning all females in these species are able to construct nests and reproduce. Females make nests by burrowing into the ground, but some species make use of tree cavities or build nests out of mud. Some of these wasps can grow to almost 2 inches long, although this particular species is less than 1 inch in length.
When I first saw this wasp land on butterfly milkweed I thought it was some type of large bee species because of the hairs on its body and its nectar-eating behavior. But with some help from the Wise Lab at the University of Illinois at Chicago we concluded this is a type of sand wasp, probably Bembix americana.
Females in this species dig burrows in sandy soil and commonly prey upon flies to bring back to the burrow to provide sustenance for larvae. It’s very difficult to find sand wasp nests because the female covers up the entrance to protect the larvae and digs a new way in every time she brings back food. Larval sand wasps consume the cached insects as they grow but will eat only nectar from flowers after reaching maturity.
It certainly is amazing that we constantly see new species at Nature Boardwalk—it seems like every day is a new photo opportunity. If you want to try to spot Bembix americana, your best bet is to look around the southeast section of Nature Boardwalk between the People’s Gas Education Pavilion and Ulysses S. Grant Memorial. The soil there is rather sandy, and there is plenty of butterfly milkweed in bloom.
If you’re really lucky, you may even see one burrowing. Nature Boardwalk at the Lincoln Park Zoo is an urban oasis for species of all shapes and sizes!