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Green June Beetles

Green June Beetle, Cotinis nitida (Coleoptera: Scarabaeidae).
Green June Beetle, Cotinis nitida (Coleoptera: Scarabaeidae). (Photo: ©2016, Arthur V. Evans)  
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Blue-winged wasp, Scolia dubia (Hymenoptera: Scoliidae)
Blue-winged wasp, Scolia dubia (Hymenoptera: Scoliidae) (Photo: Judy Gallagher, Wikimediacommons.orgCC-BY-2.0)  
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Entomologist Dr. Art Evans and VPM producer Steve Clark discuss green June beetles and their nemesis, the blue-winged wasp.

Transcript:

Steve Clark:  I'm Steve Clark with Dr. Art Evans, entomologist, and this is What’s Bugging You.  Talking about June bugs.

Art Evans:  Have you seen any lately?

SC:  No.  Well, I saw one.

AE:  The green June beetle?

SC:  Yeah, the one that looks like a blown up Japanese beetle.

AE:  I guess that's why some people call them Chinese beetles.  I just learned something.  I never understood that.

SC:  I’ve never heard that before.

AE:  Yeah, they’re native beetles.  They have nothing to do with China (laughing) or anywhere else for that matter.  I mean they're found throughout eastern United States, especially in the south, and they’re certainly common here.  I recently went on a road trip and returned to my house to find my yard full of them for the first time ever.  They finally discovered our compost heap.

SC:  Are they breaking it down?

AE:  Their larvae will.  The females look for piles of grass and decomposing plant matter, and that's where they lay their eggs, and the big finger size grubs will gobble that up in no time, so they're great for compost piles.  And the grubs are very distinctive too.  Not only are they large, as I said, finger-sized, but they crawl on their backs.

SC:  I didn't know that.

AE:  (laughing) Yeah, so they're very, very conspicuous when you see them out and about, which sometimes happens if their habitat gets flooded or you’re out there rototilling or digging or whatever.  On related note, my inbox also filled up to more than capacity while I was away with all kinds of requests for insect identifications, and people send along pictures of different things.  But one of them that caught my eye came in from one of my neighbors, who is also nurturing a native plant garden.  On her mountain mint were these wasps that she had not seen before.  And she sent me a picture, and I recognized them right away, Scolius dubia, parasitic wasps.  They're beautiful looking.  They're very bristly.  They're black with an orange abdomen and two very distinctive yellow spots on the back of the abdomen.  They have steel-blue wings, which have very fine parallel wrinkles on the tip, very spectacular wasp.  But the reason I mention them now is that their biology is such that when the females have mated, they burrow into the soil looking for grubs of green June beetles.  And there's some speculation that they might also parasitize the grubs of Japanese beetles too.  

SC:  Well, and may their tribe increase.

AE:  (laughing)  We can, we can hope so.  But I have never seen those wasps before in my neighborhood either.  So it'll be interesting.  Maybe I'm doing my little part to help fuel that particular wasp population.

SC:  Well, I'm certain that I have plenty of grubs, because I have plenty of moles.

AE:  Oh, okay.  So you're keeping the moles in business.

SC:  Yes.

AE:  Well, in order to keep wasps in business too, you need flowering plants.  This particular wasp likes mountain mint.  They also go after goldenrod too, sort of the late summer, early fall flowers.  And some people will run across mating swarms of these wasps and not realize what's going on or worse yet think it's something that needs to be dealt with.  (laughing)

SC:  Right.

AE:  But the males and females will engage in these swarms low over the ground, and they will fly repeatedly in “S” patterns or “figure-8” patterns until they couple.  And then it’s soon after mating that the female goes on her search for scarab grubs.

SC:  Dr. Art Evans is a research associate at the Virginia Museum of Natural History.  You’ll find photos, audio, and links to the museum and Art’s Facebook page at our website address vpm.org/bugs.


Dr. Arthur V. Evans teams up with VPM Radio producer Steve Clark for a weekly feature, “What’s Bugging You?,” which airs during NPR’s Morning Edition. The program takes its name from another of Evans’ books “What’s Bugging You – A Fond Look at the Animals We Love to Hate.”

Tune in each Tuesday at 8:45 a.m. or at 5:44 p.m. on VPM News