Harvesting Rainwater: How to Prevent Mosquito Larva?

Location?

South Northants, UK

Search the web for information on rain barrels. They make them with lids on that prevent the mosquitoes from coming in. The down spout from the gutter fits right into the lid.

A drop of oily stuff on the top of the water will suffocate the larvae and might keep them away.

Mosquito's like vent pipes (the larvae might be coming from the back). A nylon stocking over the outlet held down by a rubber band may block the entry point.

A repellant may also help.

Do you know of one that works?

mosquito fish!

http://www.liveaquaria.com/product/prod_Display.cfm?siteid=21&pCatId=1530

I didn't know about them thanks, my (cheap) goldfish eschewed mosquito larvae in the pond (it's not as fresh as in the picture nowadays) I stopped feeding them in the end so they had no choice.

common household bleach. It kills the larvae, and sanitizes. What more could you ask for? Just don't use a high concentration, as it will negate any effects of your sewage treatment system from growing and maintaining the correct bacteria to break down the solid waste particles.

Adding the stocking as a sieve would be helpful as well.

Abate cake insecticide.

Bleach is the correct answer :) Actually, any lighter than water oil could work, but please be kind to the environment.

A cip full of Kerosene in the header tank should work assuming the header tank does not empty completeley it shouldnt enter the cistern and last for quite a while

Of course, the problem is that a header tank is a header tank. It can't be covered and still collect rain. Or can it? But you say the tank is pump filled. So where is the rain captured (apart from an open reserve tank), and what is the surface area? If large rain catchment area, then spraying with cooking oil or other substance might be unfeasible. What exactly do you mean by "coming in"? To the toilet bowl? Since you say the dye in the cistern (?) makes larvae invisible (even when fluttering about?) it must be the bowl where they're being seen? Surely you're not climbing the header tank? Please clarify so answers to your question can be more focused--and also feasible.

I direct the gutter downpipes into two butts, then pump from the butts up to the header tank. The mosquitoes get in via the butts, the difficulty with blocking the butts is the entry / exit of cables and pipes (it's a submersible pump). I could dose with bleach but worry about how much to use and that would rule out goldfish (great idea - Bob Flowerdew is a proponent) as would the fact that in summer I pump the butts dry.

"Butts." Not familiar with that word; perhaps a colloquialism. Would it be the thing shown in your avatar? Anyway, if the butts are large enough for fish, then fish would be your answer, it seems: to consume the larvae. No need for oil or bleach. But if you wanted to use either (oil or bleach), I think any kind of inexpensive (vegetable derived) cooking oil would be the better choice. Why? First, not (as) much is required--it suspends on top as opposed to dissolving. Second, any "water-breathing" creature (i.e., below the surface) will not be affected (by something suspended rather than dissolved)--however, larvae are air breathing and must come to the surface (where they stay most of the time anyway). If fish injested minute amounts of oil along with the larvae, I can't see any harm to them by digesting vegetable product--essentially, something that is in the environment naturally--and the small amount of spraying needed would not make very much available to the fish anyway--but would be enough to prevent any uneaten larvae from emerging as adults. Might want to check with your fish dealer for their input as well. Awaiting your feedback. And thanks for the clarifications.

As I see covering up the tank tighly is the best solution.

I believe using a thin film of oil also will be a more feasible solution, provided you do not empty the tank which may take the oil to the sewer.

Using household bleach or any other disinfectant will also kill bacteria in the sewer tanks and in no time you will have another problem- overflowing sewers! However after adding bleach if you do not allow treated water to go to the sewer for may be 24hrs it will be ok.

If it is a tank open to air having a few guppies or some other hardy fish (of course with a net at water outlet to prevent them going out would be an ideal solution). A point to consider. Use only either female or male unless you do not feel sorry for the fish fry which may go down the toilet!

Have fun eitherway. You are doing something great for the society by using rain water harwesting unlike many technical people who just talk about protecting environment. Keep doing good things.

I know a guy that leaves the top open allowing the bugs to come in. He then buys some goldfish every spring and tosses them in. They have lots of room and food for the summer. Come fall he nets them and sells them back to the pet store!

By the way this is in Canada so things freeze in the winter. Perhaps in the UK you could leave them in there longer.

Hi there.

There are some screens (typically fitted to tank overflow outlets, or ends of pipes) that are used in australia. http://www.rainharvesting.com.au/insect_proffoing_your_tank.asp

might be worth a try?

Again, great stuff I didn't know about. I like the auto-siphoning cleaning mechanism from this site. Thanks. Things have improved since I set my system up. Mine is a bit Heath-Robinson

How about putting a floating pool chlorinator in the the tank.

They are quite cheap and you'd only have fill it once in a while. See the link for an example of what I'm talking about.

http://www.cheappoolproducts.com/20_21_29_Chemical~Feeders_44~supplies.html

Thanks, I didn't know these things existed. I've now dosed with bleach, but this is a set and forget solution that suits my poor memory. I'll look for on in the UK

I've always just kept some movement on the surface of the water (in Upstate NY, USA). A simple home fish tank pump directed to the top of the tank should do the trick.

Let me know if it helps.

-Cooter

This is just the sort of idea I was looking for, I didn't think of this. On an interesting note, the kind of dust shells they develop in form on on the inside of my plastic butts, but not on some old copper hot water cylinders I'm also using.