Wasps in a big network of tunnels? Near a bumblebee nest?
Dear Bugman,
My husband and I just moved into our first home. Much to my surprise I noted that there were over 20 holes dug into the dry dirt of our yard around the deck. After a bit of spying I noticed that small insects were flying into them. The holes are about the width of a standard pencil, sometimes smaller. They are reopened quickly after filled with dirt. We have a number of abandoned quarter sized holes in our yard, and while watching the mystery bug I noticed that two of those appear to be entrances to a bumblebee nest which we would like to leave undisturbed as they are bee-coming rare (sorry, couldn’t help it). The closest thing I have found searching the web is a Mason Wasp or Potter Wasp, but I’m not certain by any means, and nowhere can I find information about whether they sting, or return to the same nest year after year. We would like to till and plant in the fall after the bees abandon their nest, but if there is a huge area of wasps that may not be wise. Attached is a picture of our mystery bug, a picture of him digging, a picture of the affected area, a picture of the burrows, and a picture of the nearby bee nest outlet. Thank you so much for your time and expertise.
Panicked Homeowner,
Amy White

Hi Amy,
We are happy you did not sign your letter “Desperate Housewife” and you really have no need to fear. The wasps and bees are unrelated and as you have determined a course of action for the bees, we will just address the Sand Wasps. We cannot identify the species, but your Sand Wasps appear to be in the Tribe Nyssonini, based on images posted to BugGuide. Though Sand Wasps are solitary, they do tend to nest in proximity to one another, in a communal situation rather like a housing development. They are not aggressive, and will not attack. We will contact Eric Eaton to see if he can add anything or refute our reply in any way.

Update: (07/25/2008)
Hi:
The “sand wasps” are known as “beewolves” in the genus Philanthus. The females are solitary, each digging her own nest burrow. These wasps hunt and paralyze small bees (mostly “sweat bees” in the family Halictidae) which they stock in the nest as future food for their offpsring.
Eric

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