Solitary Wasps Making a Home at Nature Boardwalk


A close look at the solitary wasp spotted 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.


The wasp poses among some butterfly milkweed.

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!

Mason Fidino

Mason Fidino is coordinator of wildlife management in Lincoln Park Zoo's Urban Wildlife Institute.

Comments

My husband and I were at the zoo about a month ago, and we did notice the wasps in tremendous amounts!! They are really quite interesting and they did not seem to mind us watching them (luckily). In our neighborhood we seem to be seeing more and more lawns being infested with a larger wasp and it captures cicadas and drags them down into its burrow. Although I have read that they are harmless to humans, people are really freaking out if they invade their lawn. They are rather scary looking because they measure up to 2-3 inches. My understanding of this wasp is that the female uses the cicada body to lay the larvae in, using it for food, and the male wasps fly about the outside of the burrow to protect it. My only concern is what people are putting down on their lawns to try to get rid of the wasps. One of my neighbors covered their lawn with plastic all last summer, trying to smother them. Then they turned the lawn over in spring with a tiller, and replanted the lawn with seed. All this was wasted effort. The wasps came back this summer, and the neighbors are really upset. Is there some kind of climate change or an over abundance of cicadas that these wasps are invading our city on the northwest side? Thank you for any reply!!

Sharon, Mason responds:

"The wasp you are talking about is the eastern cicada killer wasp, which has been previously discussed in the blog. This particular species most commonly digs burrows in disturbed areas (lawns with short grass would fall into that category). I can't say if a climate change or overabundance of cicadas has increased the amount of this wasp species. However, suitable habitat for this particular species has increased greatly over the past 200 years in the United States due to anthropogenic change, which could be a reason why they are so abundant.

I can't give any tips as to how to deal with these wasps, but searching the internet can yield a variety of solutions if you do not want them in your lawn. I can't attest to the success or safety of any method. Time is also on your side, as this species is very short lived (lasting only about two months). However, if you don't mind their presence they are truly a sight to behold. Especially if you see a female bringing a cicada back to her burrow!"

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