What are these grubs and beetles and will they harm my garden?

May 1, 2011 5:08 PM

What are these grubs (and possibly related beetle) that I found in our vegetable garden today?

I found these just under the soil surface in Washington, DC in a garden used to grow vegetables for the past few years, mostly tomatoes.

I've seen the grubs before (in autumn I think), but today noticed that one section of the garden had large numbers of grubs and this was the first time I'd seen a few of these beetles nearby.

The beetles (I have two more pictures that I don't think would help, but just in case: 1 and 2) would "play dead" when disturbed and eventually try and burrow away (when not cruelly contained in a green plastic bowl).

The largest grubs are about an inch long.

I thought the grubs might be Japanese beetle grubs, though it seems the beetle here is not. Maybe it's just a coincidence that the beetles were nearby. I've already sent pictures to whatsthatbug.com.

posted by exogenous to Home & Garden (6 answers total)

They are the larvae of some member of the Scarabaeidae. Most likely, they're May beetle larvae. They feed on roots and are considered pests. The ground beetle next to them is a predator.
posted by Nomyte at 5:16 PM on May 1, 2011

I was gonna suggest that they do look like Japanese beetle grubs. Not sure about the other beetle.
posted by Lou Stuells at 5:17 PM on May 1, 2011

The beetle is a Carabidae (most likely), scarab beetle larvae.
posted by bolognius maximus at 6:28 PM on May 1, 2011

Thanks folks. Whatsthatbug.com wrote back indicating that the grubs are scarab grubs, most likely June Beetles [I think these are the same as May beetles as indicated by Nomyte above] and that the beetle is a predator, likely Scarites subterraneus.
posted by exogenous at 7:27 PM on May 1, 2011

By the way, smush them with extreme prejudice. They can crawl quite a long distance out in the open air.
posted by desuetude at 9:22 PM on May 2, 2011

I left the grubs out in the bowl hoping the birds would eat them in lieu of my blueberries, but most of them were still there (and lifeless) when I checked back the next day.
posted by exogenous at 7:43 AM on May 3, 2011