Wood Boring Larvae
January 12, 2010
Recently, while removing a mimosa tree
(beneath power lines), I discovered some wood boring larvae. The main body is about 3/4″ long, with a tail a bit longer than the body. One didn’t survive the chain saw.
Could this be a type of horntail wasp larva?
We believe these are the larva of a Drone Fly, Eristalis tenas, which are called Rat Tailed Maggots. According to BugGuide: “The adults feed on nectar from flowers and are often seen hovering in front of flower blooms in gardens in both urban and rural areas. The larvae feed on rotting organic material in stagnant water in a variety of locations. Life Cycle The larva of the Drone-Fly feeds on decaying organic material in stagnant water in small ponds, ditches and drains. Such water usually contains little or no oxygen and the larva breathes through the long thin tube that extends from its rear end to the surface of the water and that gives it its common name of ‘rat-tailed maggot’.“ We have not heard of them boring in wood, though BugGuide has an image of one that was ” found in a trash can filled with water and old logs. Most seemed embedded in the log surface. “ Your letter did not indicate if the tree was decaying. We have not heard of Rat Tailed Maggots living other than an aquatic environment, but according to a University of Kentucky report, “The maggots can be a nuisance when they crawl away from their breeding site to find a dry place where they can transform to the adult stage.“ Your letter did not indicate if they were found deep inside the wood, or in the bark. We wish we had that information. We are going to check with Eric Eaton to get his opinion on this.
Confirmation from Eric Eaton
You are correct about the rat-tailed maggots. I wonder if there was a hole in the tree that had collected water and/or decaying leaves and other organic matter. That would explain things right there.
Thanks so much for identifing this unusual maggot. It makes sense, as the tree had a hollow. (But no water in the hollow at the time of cutting) They fell out when the tree was felled. There were burrows in the wood that hadn’t rotted and just assumed thats where they came from.
I’ve observed the drone flies but had no idea of their larval stage.
Thanks again! Larry
P.S. I would like to submit a query on the identification of a peculiar grasshopper that likes water. It will take some time to find the photo.