What's That Bug? does not endorse extermination

Weird water caterpillers with tails?
Location: Ypsilanti, Michigan 49198
May 15, 2011 9:05 pm
So my friend has a ”backyard pond” that gets cleaned at the begining of spring every year and that’s really about it. Its more like a cement hole with water. There is no fish or plants just water. Anyway, his 15 year old sun was cleaning the ”pond” out today and found these things that look like worm/caterpillars with a long thin tail. They wriggle in the water and swim slowly about. The smaller ones were close to the top of the 3 foot deep pond but the bigger ones started to come up when he had removed half the water. Can you help us identify them?
Signature: Shellin and Damon

Rattailed Maggots

Dear Shellin and Damon,
These are Rat-Tailed Maggots, the larva of the Drone Fly.  They are often found in stagnant water and the “tail” is actually a breathing tube.

What's That Bug? does not endorse extermination
Location: Michigan

31 Responses to Rattailed Maggots

  1. nanette rambo says:

    found some in Iowa in sandbox with water

  2. gardener says:

    Found them in Berekely, CA

  3. Barb says:

    Rattailed maggots found in Astoria, OR in a container of stagnant water with a dead rat.

  4. olivia says:

    m and my friend were at a pond in calgary alberta and found one sitting on our blanket! my friend at first thot it was a mouse! lol

  5. Laurence Feeney says:

    Manchester U.K. They swim and curl around others in a group .
    Are they beneficial or a pest ?.

    • bugman says:

      Adults are pollinating insects, so they are beneficial. Larvae help to break down organic matter, so they are also beneficial.

  6. sarah says:

    Found Southern some in California. They were in my old pond a month or so after a good rain filled it half way.

  7. Shontae says:

    Found some in Fayetteville, NC. ugh!

    • Laurence says:

      They certainly look strange , but wait till they mature into flies. Then they are quite charming. They do not annoy you at all, and hover in one place for seconds , before darting off to who knows where.
      Having planted up my pond , I don’t have any this year, maybe they need stagnant water ?.
      I have however got lots of “wood ” bees , with what I understand as lots of males fighting each other endlessly, even when it is raining.
      These too do not bother humans. They “Buzz each other endlessly until they drop to the ground exhausted . I have given these fallen ones honey, and it seems to revive some of them, but then they fly up again and continue fighting. This has been going on now for 7 weeks or more.
      I’m half expecting them to nest in my loft, as this is where the activity is.
      Any comments?.

  8. Matt Huffman says:

    We found them in las Vegas NV thanks for the info very cool web reference thank you

  9. Gabe swindler says:

    I found some in my little make shift pond that also had some water beetles in it. there really cool i doing a report on them.

  10. Cheyenne says:

    Found some in my kids wading pool. First time for everything! Bizarre little fellows. My five year old was calling them Rat Tails. Apparently he knows more than mommy! Drewsey, Or

  11. WALES says:

    found some in my pond – pretty cool!!

  12. I found some In my laundry room. My AC is leaking and the water is coming in through the door. My 2 yr old daughter pointed it out as I was pulling clothes from the dryer. Should I be concerned with my babies in the house? I live in Florida. Sincerely, Momma of a full house.

  13. Ute Gersch says:

    Have found rattail maggots in a bucket of soaking weeds which we use as fertiliser on the garden. I didn’t know what they were, & put them in bran like you do maggots for fishing but some died so put the others back in a jar of water with plant cuttings & they are ok & growing longer tails.l’m in my 70s , gardened all my adult life but have never seen these maggots before.

  14. Araven says:

    I discovered a bunch in the Hollywood Hills, near the HOLLYWOOD sign in a large pot in my yard that had some stagnant water from the last rain. Glad they are harmless.

  15. Diamond says:

    My 3 year old brought me one while we were picnicking outside. We have been watering our lawn and there are puddles of sitting water for a few days now. I’m sitting on our bench and they are crawling all around the ground. Ive never seen these before. Northwest, Montana. June,2017.

  16. Toni says:

    Just read this thread as found these creatures in a bucket holding wood, it’s rained and the wood has been sat in water…have to say they weirded me out! Southampton, UK

  17. Mako says:

    Was treating the secondary septic tank in the system with beneficial bacteria tonight. Lifted the cap out of the lid and found them swimming around in the water. About 2 inches long and a quarter wide. Undulating and pale, slightly translucent. Amazing but creepy.

  18. Rich says:

    North Dallas, Texas.: After a rain I found them in the gutter in the remaining rain water. They were burrowing into the sand/soil in the cracks and crevices in the concrete. 8/5/2017

  19. J.J.P says:

    Found them in Alegria S.I. N. Samar,Philippines they look creepy…

  20. Todd says:

    Found in Fort Oglethorpe, Ga. had no idea what they were, thank you for the info. Excellent website. Are drone flies also called horse flies?

  21. Kenneth Rubiera says:

    Found them in a ditch in Wellington, Florida after Irma. My son and I were biking around the neighborhood and he stoped by a large pile of debris to show me some starfruit because he didn’t know what they were. He noticed these and pointed them out. I had never seen them before. Thanks for helping me answer his question. I’m a den leader for the scouts and I saved your site, I’m sure it will help me again.

  22. Kelly says:

    I found these in Louisiana in some very dirty buckets full of very stagnant water and what I think was cigarette butts. I had never seen anything like it before and I was a little creeped out. I was going to have my husband get rid of them, but thank to this site, I’m going to leave them alone and let them grow into flies. Thank you for teaching all of us about these interesting little creatures!

  23. Susan Mentzer says:

    I found some in Grapevine, TX. I had a tote bin with some old magazines in it that I was intending to take to recycling. I didn’t realize that the lid leaked. I opened it, it was half full of stagnant rainwater, waterlogged magazines & those weird critters. Beneficial or not, they really creeped me out! I set them free in the storm drain. Thanks for the identification, at least I won’t have nightmares now.

  24. Lorri Andrews says:

    How far north do these go? Found some in stagnant water just east of Edmonton, Alberta, Canada.

Leave a Reply

Your email address will not be published. Required fields are marked *