cocoons in comfrey tea
January 23, 2010
I just found clear, wriggling cocoons in my comfrey compost tea. you can see the bug inside the cocoon, a long black object with wings wrapped around. they have long stringy tails and are all bundled in a mass together. they do not look like maggots and they are roughly 1 cm in length. can you help me? i could not really get good shots as my camera is not much of a close up one.
shayni
New zealand, north island

Rat Tailed Maggots in Comfrey Tea

Dear shayni,
Our first thought on this is that we need to research exactly what the pupa of the Rat Tailed Maggot looks like, and then we need to see if comfrey tea is the name for the liquid fertilizer that is made by brewing manure in water.  You are right about your photo being blurry, but it does give a general idea of this mass of insects, but alas, the details must remain in our imagination, though that has been known to be rather vivid at times.  We see we were wrong about the comfrey tea, which is made from the plant comfrey, Symphytum officinale, and is applied externally to a number of conditions including bruises, cuts and acne, and that it might be used as an organic fertilizer.  It appears you have brewed it outdoors in a large bucket, which is why you have what we suspect your insects are Rat Tailed Maggots.  Rat Tailed Maggots are the larvae of Drone Flies, Eristalis tenax,  According to Charles Hogue in Insects of the Los Angeles Basin:  “the larvae live in water, usually in sluggish streams or small stagnant ponds that are foul with organic matter; they may also breed in fresh liquid cow manure.  Because of their extremely long, extendable posterior breathing tube, the larvae are called ‘Rat-Tailed Maggots.’”  We then found an online article entitled Eristalis tenax and Musca vomitoria in New Zealand by G.V. Hudson, F.E.S. that was read before the Wellington Philosophical Society on the 2nd October 1889.  Suddenly, your simple letter opened up an entirely new can of worms since the Drone Fly was reported in New Zealand prior to 1889:  Is the Drone Fly a truly cosmopolitan species because its range expanded naturally?  Or was it spread by man?  Mmmmmmm.  BugGuide has some excellent images of Drone Flies mating and BugGuide indicates the Drone Fly was introduced to North America prior to 1874.  We can’t help but wonder why and how Drone Flies were introduced to North America.  This could be a graduate thesis topic, but alas, at some point, we need to stop and respond that you have Rat Tailed Maggots in your Comfrey Tea.  According to Wikipedia:  “When fully grown, the larva creeps out into drier habitats and seeks a suitable place to pupate. In doing so it sometimes enters buildings, especially barns and basements on farms. The pupa is 10-12 mm long, grey-brown, oval, and retains the long tail; it looks like a tiny mouse.“  We should also mention that the adult Drone Fly is a perfect mimic to the adult Honey Bee, and this mimicry is in itself interesting in that both the Honey Bee and the Drone Fly are connected to human agriculture and animal husbandry. Mmmmmm.

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?
Larry Taylor
Central Oklahoma

Rat Tailed Maggots

Hi Larry,
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
Hi, Daniel:
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.
Eric

Daniel,
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.