Robber Fly Question

Subject (please be succinct, descriptive and specific):  Robber Flies
Date: 07/21/2019
Time: 07:46 PM EDT
Your letter to the bugman:  A few years ago our property was somehow blessed with the presence of a gang of robber flies. My assumption is they came in on some dead trees that were brought in for milling. They have stuck around for several years now and I would like to make sure they are here for many more. They defend my porch voraciously against the vicious yellow jackets who were the previous residents before the robber flies came. Is there anyway I can insure the survival of the gang? Can I put up nesting sites or winter shelters of some sort? I noticed this year the gang is noticeably smaller after the harsh winter we had. I really don’t want to lose these guys.
Your name:  Tareesa

Bee-Like Robber Fly eats Yellowjacket in British Columbia

Dear Tareesa,
Do you have one or more images of your Robber Flies?  If you do, please attach them to our response, but in the future, please use our standard submission form by clicking the ASK WTB? link on our site.  That way we would also have your location, an invaluable bit of information for identification purposes.  Knowing your exact species of Robber Fly might provide more specific information.  We located this family information according to BugGuide:  ” larvae usually in soil or decaying wood” and “Minimal courtship behavior. Females lay eggs in the soil or in plants. A few, such as
Mallophora and Megaphorus, form an egg mass on a plant stem (photo here). Larvae often predatory, consuming eggs and larvae of other insects in decaying matter. Typically overwinter as pupa, emerge in spring. Life cycle is 1-3 years.”  It seems rotting wood is the ideal habitat to encourage their presence.  The fact that you have had them for several years is evidence they have what they need, including Yellowjackets for food.

Thank you for the quick reply. I live in northern AZ. I don’t have a picture as these guys are VERY active. It took me forever to ID them and it wasn’t until I witnessed a midair snack session that I was sure of what I had. They are the large black and grey type with the tapered abdomen.Thank you for the additional information and the link. I will be on the look out for the larvae now. I freaking love these guys.

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