Results 1 to 13 of 13

Thread: How to kill dragonfly larvae

  1. #1
    Join Date
    Jun 2016
    Location
    Perth WA
    Posts
    613

    Default How to kill dragonfly larvae

    G'day all
    Dragonfly larvae are decimating my mountain minnow fry in the pond.
    Can someone recommend a treatment and possibly place to buy it in WA.

    cheers
    Merv

  2. #2
    Join Date
    Jun 2013
    Location
    ACT
    Posts
    13,803

    Default

    Hiya Merv, AFAIK, prevention may be the only option. Any control including biological will destroy your fry.

    Maybe macrobrachium?

  3. #3
    Join Date
    Jun 2016
    Location
    Perth WA
    Posts
    613

    Default

    A month ago their was at least 2 batches of fry. They disappeared but i put it down to the cold. 3 days ago new fry were around and yesterday they were gone.
    Checked with a torch this morning and found at least 1 dragonfly nymph so there could be any number in the pond.
    I have read that diflubenzuron can be used safely with fry but i'm having trouble finding it.
    Really don't want to do a full clean out if possible.

  4. #4
    Join Date
    Oct 2008
    Location
    Central Coast - Narara
    Posts
    6,006

    Default

    Full clean is pointless as they will just lay more eggs.

    I have Dragonflys breed in my pond and still have plenty of White Clouds.

    Maybe there is some other cause.....


    Ado
    Whatever

  5. #5
    Join Date
    Jun 2016
    Location
    Perth WA
    Posts
    613

    Default

    Quote Originally Posted by BigDaddyAdo View Post
    Full clean is pointless as they will just lay more eggs.

    I have Dragonflys breed in my pond and still have plenty of White Clouds.

    Maybe there is some other cause.....


    Ado
    I'm looking for other reasons BDA but not much else to cause it.
    Different dragonfly larvae, perhaps from different states, might have a different appetite. I have seen 3 of the WA ones wipe out a small pond of fairly large tadpoles in short order.
    I saw Rachel O'leary use some type of chemical to get rid of larvae in her out side tubs. Just can't find the vid now when I need it.

  6. #6

    Default

    Dragonfly larvae are known predators of small fish, shrimp and other aquatic organisms. If they are in the pond, you have to physically remove them, which means stripping the pond and washing everything and then covering the pond with flyscreen to stop the adults getting back in. Any chemicals that kill the insects also kill fish.

    When you do clean the pond, go over everything in it. The larvae can hide on plants and other things and will eat everything.

  7. #7
    Join Date
    Jun 2013
    Location
    ACT
    Posts
    13,803

    Default

    Maybe a few gouramis or paradise fish may clean them out rather than having to strip.

    As mentioned, maybe it's another problem?

  8. #8

    Default

    If the dragonfly larvae are more than 1/2 inch long, paradise and gouramis fish won't be able to eat them. Big gouramis might but they will also eat the baby white clouds. Plus if you add gouramis you risk introducing TB and the Iridovirus into the pond. Best to avoid gouramis until the breeders in Asia get their act together and disinfect their ponds and get new stock.

  9. #9
    Join Date
    Oct 2008
    Location
    Central Coast - Narara
    Posts
    6,006

    Default

    The chances of you being able to completely remove them and any eggs from the pond are basically zilch IMO.

    Maybe remove all of the fish, etc. and then treat the pond. You can then reintroduce the livestock.
    Whatever

  10. #10
    Join Date
    Jun 2016
    Location
    Perth WA
    Posts
    613

    Default

    The Koi Society of WA have a suggestion of using Dimilin (diflubenzuron ), but it is pretty hard to find.
    I think removing the adults to spawn in a safe tub is going to be my best bet.

  11. #11
    Join Date
    Jun 2013
    Location
    ACT
    Posts
    13,803

    Default

    Quote Originally Posted by Madmerv View Post
    The Koi Society of WA have a suggestion of using Dimilin (diflubenzuron ), but it is pretty hard to find.
    I think removing the adults to spawn in a safe tub is going to be my best bet.
    Interesting chemical.

    I reckon it will decimate your fry. The adults will probably survive though.
    https://www.sciencedirect.com/scienc...32045608001269

    actually it looks to be ok.
    https://setac.onlinelibrary.wiley.co...etc.5620020309

    I stand corrected.
    Last edited by Rebel; 27-09-18 at 02:26 PM.

  12. #12
    Join Date
    Dec 2013
    Location
    sydney,nsw
    Posts
    27

    Default

    Have enough space for the minnows to swim in, suggested to around 400mm deep, and wide at possible. I can see my minnows happy watching the dragon fly larvae who has litttle chance of getting these faster swimming minnows.

  13. #13
    Join Date
    Jun 2016
    Location
    Perth WA
    Posts
    613

    Default

    Quote Originally Posted by otah1 View Post
    Have enough space for the minnows to swim in, suggested to around 400mm deep, and wide at possible. I can see my minnows happy watching the dragon fly larvae who has litttle chance of getting these faster swimming minnows.
    These fish are in a pond that is almost 1m deep and the adults are fine.
    I have purchased 2 tubs, 200l, and will be moving the fish soon for a few weeks. Any fry in the tubs can grow up predator free.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •