Sunday, November 18, 2012

Scarab Beetle Larva (White Grub)

In my quest for slug eggs today, I uncovered a white grub in its burrow. Lifting it out with a stick, I took some photos and identified it as the larva of a Scarab Beetle (family Scarabaeidae). There are many kinds of scarab beetles, so this grub could turn into a June Bug (also called June or May Beetle, as well as Chafer), or a Japanese Beetle (Popilla japonica). These larvae can be very destructive to one's lawn in large numbers. So far this is the only one I've found, and it seemed more interested in burrowing than eating.

If anyone knows what kind of beetle this grub will turn into, please let me know. I think it could belong to the subfamily Melolonthinae, tribe Melolonthini, maybe genus Phyllophaga? That may be wrong, and I'm really not sure you can identify the species (if at all) without examining the larva more closely. I didn't realize the ID would be so difficult.


http://oclm.com/2011/11/what-are-white-grubs/
Richard Fox of Lander University discusses the dissection of a white grub:
http://lanwebs.lander.edu/faculty/rsfox/invertebrates/cyclocephala.html. If you want to learn the anatomy of white grubs, this site has some awesome diagrams. I recommend it.

References:
http://bugguide.net/node/view/187/tree (taxonomy)
http://bugguide.net/node/view/3477 (genus Phyllophaga)
http://bugguide.net/node/view/473 (Japanese Beetle)
http://www.ent.iastate.edu/imagegal/coleoptera/scarabaeidae/ (Scarab Beetles & White Grubs)
http://www.ca.uky.edu/entomology/entfacts/ent10.asp (controlling white grubs in turf grass)
http://entnemdept.ufl.edu/creatures/field/white_grub.htm (common white grubs)
http://www.corkyspest.com/plant_pests/junebeetle-whitegrub.html
Posted by at

1 comment:

  1. MasterHiFiOctober 14, 2019 at 4:54 AM

    Hi,

    I know this is an old post, but last night I saw a HUGE white grub cruising across my walkway and then burrow into the earth with surprising speed and efficiency. This morning there was a significant pile of fresh earth above where it had disappeared.

    Two things threw me off. First, it moved or undulated like a caterpillar, which is what I thought it was at first. But upon closer inspection I could clearly see that it was a grub, just with surprising mobility.

    Secondly, it was big. Living in Brooklyn, you get used to big bugs, particularly the ever-present German cockroach. But larvae of this size are unexpected. I have a rotting stump in my back yard and have luckily seen a number of the mocha-colored North American Stag or Horn Beetle - the largest beetle in North America. But their grubs live in the wood and are not mobile (though possums and raccoons dig them out).

    It took a LOT of searching to learn that this encounter was likely the Green June Beetle, a number of which I've caught over the years. I love their beautiful metallic green and fine tan detailing.

    Also, their grubs exactly fit the bill of being very large, well over an inch long (I'd say the one I witnessed was easily 2 inches), as well as being mobile, especially at night, and having the peculiar practice of undulating on their backs, giving their motion the appearance of a caterpillar. What is especially shocking is the size of the grub relative to the size of the adult beetle.

    So if the specimens you have pictured above are as large as they appear, that is an inch-plus in length, then they are probably the Green June Beetle grub. You also mention its preoccupation with burrowing, which is exactly the behavior I observed as well.

    I'm glad that I finally found an explanation for what I witnessed as it was a most unusual sight, and literally sent my female companion running...

    Best,
    MHF

    ReplyDelete

Subscribe to: Post Comments (Atom)