Sunday, October 10, 2010

Great Golden Digger Wasp

I met a new yardmate yesterday - a great golden digger wasp (Sphex ichneumoneus). Isn't that a cool name? She (he?) was nectaring on my Wichita Mountains goldenrod - the overgrown stuff with the bad case of rust (that I presume developed after it spent most of the summer almost overwhelmed by seedling brown-eyed Susans). To give you perspective, this little black and red beauty is an inch least! She totally ignored my attempts to get the camera close and closer as I took photos, so the nectar must have been pretty darn good and not have been too affected by the rust.

Doing my normal bit of research after finding a new species that I don't recognize, I learned that great golden digger wasps are closely related to the giant cicada killer wasps, with very similar habits. One big difference, though, is that their prey are grasshoppers - crickets, short-horned grasshoppers and long-horned grasshoppers.

Like the cicada killers, the females did a hole in the ground, then go in search of their prey. Finding it, they paralyze it and drag it back to their nest. Once they've stocked the nest adequately with (in this case) paralyzed grasshoppers, they lay an egg on each grasshopper and seal up the nest. The eggs hatch out shortly afterwards and the young wasp grubs eat the grasshoppers provided, staying in their snug earthy nests until the following summer, when the life cycle repeats.

These are not aggressive wasps - according to all the reading I've done, you basically have to handle them or step on them to get stung, and handling them doesn't guarantee a sting. If they do sting, however, the sting is very powerful, so it's wise to be a bit cautious around them. There are numerous reports of people coexisting quite peacefully with great golden digger wasps building nest holes in the ground right beside their patios or in their walkways.

The adults feed entirely on nectar and plant sap.

Birds can apparently be quite problematic, learning to harass the wasps and get them to drop their paralyzed grasshoppers, which the birds then snarf up.

Texas A & M has a great write-up on great golden digger wasps, including a fascinating account of some research performed on their seemingly thoughtful behavior in building and provisioning their nests.

I'm definitely glad to have this gentle giant sharing our yard and gardens, and I'll be keeping an eye out for them in the future.

1 comment:

ProfessorRoush said...

Nice post Gaiagardener...I'll have to look a little closer at my own garden for this one.