Navigate / search

Great black wasp

This beautiful creature photographed by Andrew Hogg is not actually a “blue wasp” but a great black wasp, Sphex pensylvanicus. According to John Ascher of, only the wings are blue. It belongs to the family Sphecidae, the thread-waisted wasps, and if you look carefully at the photo, you can see the very thin connection (petiole) between thorax and abdomen.

This is a solitary, ground-nesting wasp. The adults feed on nectar and are especially fond of Asclepias (milkweed), right where Andrew found this one. The adult female feeds grasshoppers and katydids to her young. She finds a suitable meal, paralyzes it with three stings, and then brings it back to the nest. The prey doesn’t die right away, but can remain paralyzed for weeks, assuring fresh meat when the larval wasps need it. Gruesome, eh?

These wasps are found throughout North America, including Canada, Mexico, and most of the US except the Pacific Northwest. They are considered important pollinators of Asclepias and some other plants including wild carrot, snake root, and white sweet clover. They can be seen in fields and meadows on mid- to late-summer days when grasshoppers are plentiful.

The males, which are smaller than females, are known to fight each other for territory and engage in activities such as biting and grappling with their spiny legs.


A great black wasp nectaring on milkweed. Only the wings are blue. © Andrew Hogg.



Aren’t they gorgeous?! I saw one in August in Haliburton, Ontario, Canada. Very striking…do not remember seeing these as a child when I lived there. This one was feeding on an hydrangea.

Aleksandrs R.

Look impressive, but they are safe to humans? They are much dangerous?


If you are asking if they sting, yes, they sting. But are they dangerous? They are solitary ground-dwellers, which means one wasp lives in a hole in the ground by herself. How dangerous can that be? It’s a waste of life to be afraid of life.

Marci A Bohn

I have many of these going wild on oregano I let flower. They’re so pretty.


Yesterday a female black wasp stung a small Bird several times in my yard. The bird died instantly. I don’t think she mistook it for a grasshopper or katydid. It was 3-4 inches long and Big !
I am guessing the female is dangerous if aggravated.


Are these wasps harmful for monarch butterflies and milkweed? Since they started coming to my backyard, the monarch butterflies are not visiting anymore. What is happening? Thanks.



The two things are most probably not related. Correlation does not mean causation.

Leave a comment


email* (not published)


This site uses Akismet to reduce spam. Learn how your comment data is processed.