mosquitos breeding in the rainwater butt

I think the lid is perhaps not tight-fitting enough to keep out the egg-laying females.  any suggestions on how i can kill the larvae?  I need to be able to use the water for plants.   i have to scoop water out from the top, as the butt is set too low to allow a tap in the bottom.  i've read that a layer of oil or soap on the top would prevent the larvae from breathing, but i don't think that will be too good for my plants.  



  • patzzpatzz Posts: 56

    I,ve used cooking oil and it does work. It forms a film over the top.It won,t harm your plants because the oil is plant based. And you don,t need oodles either. It.s certainly been the year for the moscito

  • thanks for the quick reply!  how much cooking oil do you put in?  mine is a 200 litre butt, and quite wide at the top.  do you need to have a film of oil completely covering the surface, or just enough to have some slicks floating around?  

  • DaintinessDaintiness Posts: 949

    Bob Flowerdew keeps a goldfish in his to eat the larvae!

  • pashpash Posts: 109

    Hi, veg oil acts as a barrier and stops the larvae from breathing through tubes when they go to the surface, it doesn't have to be thick but for best results cover the hole surface area, as it acts on the surface most can be syphoned off if your dubious about leaving it in,

  • You can also add polystyrene beads, which help prevent the mosquito laying eggs in the water. If the water is used regularly, so that the water is constantly changed, there isn't much problem because mosquitoes like stagnant water, but in wet weather such as we are having at the moment, the water in the butt can be undisturbed for quite a time. So it might be an idea to empty the butt and start again. 

  • BerghillBerghill Posts: 2,831

    I add a teaspoon of a bee friendly insecticide to a 40 gallon water butt, kills off the larva and is so minute in concentration it does no harm when I water things with it.

  • gardengirl6gardengirl6 Posts: 223

    Just a teaspoon of vegetable oil in each butt will do the trick.

  • patzzpatzz Posts: 56

    Hi Rosa Rugosa, sorry i didn,t get back to you. However the replies you,ve received tell you all asked. I,m battling snails who are decimating my dahlias. It seems Pests 10 Gardeners nil this year! I like a challenge but really. Wellies in July.......

  • Paul NPaul N Posts: 222

    I have four water butts, none of which are covered, and have been like that for about 25yrs. Yes there's larvae in there but I can't say it bothers me. Perhaps we use the water more frequently. They are also up off the ground so I can fill the watering cans.

  • thanks all, for the useful advice.  i will try the oil first.  we have mega mossies here.  they have such an itchy bite, or maybe it's just how i react to them.  the itch lasts for weeks.  the fish idea is cute too!   i'd have to leave the lid off though, and then you get all the algae and stuff.......  we did have some goldfish in the pond, and  i never saw a mossie larva there.  we have lots of dragon fly nymphs, and i think they do the job too.    

    about snails - i used ferrous-based slug pellets around all the plants that are particularly precious to me, at least until they are large enough to take a bit of snail pruning.  and now i go around every evening, and spear the slugs with sharp sticks, which i then chuck in the compost.  i never used to be so merciless until i got my first lupins and clematis!  

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