London (change)
14 messages
08/05/2012 at 19:45

hi im relatively new to greenhouse gardening, i have just found tiny transparent caterpillars with black heads on my tomatoe pots. does anyone have a clue what they are and wot to do with them? jo

15/05/2012 at 08:27

thanks for your help guys!

15/05/2012 at 09:14

Obviously no-one knows! If you ever find out from Mr Google or anyone, it would be interesting to know :- )

15/05/2012 at 09:29

jo, most immature (baby) caterpillars are usually close to transparent with black heads. In short, get rid of them. No caterpillar in the vicinity of tomato plants will ever have good intentions.

15/05/2012 at 09:30

Probably of the moth family. Control by squashing them - simples.

16/05/2012 at 14:29

Hi thanks everyone. have spoken to RHS this morning and think they are fungus gnat larvae, millions of them so not possible to just squash them unfortunately! 

16/05/2012 at 14:42

An organic contact spray like pyrethrum will knock them over but you'll have to keep a close eye out for their return.

17/05/2012 at 13:42

oh thanks so much, is that ok with veg do u know?

17/05/2012 at 15:07

Yes, it's derived from Chrysanthemums. You wouldn't use it on baby seedlings - well, you wouldn't spray most things on baby seedlings. With crops, you can harvest the day after spraying. Washing the crop, obviously.

It only works on contact with the pest, it's not systemic - meaning it doesn't penetrate the plant and stay there for a lasting effect. Which means you have to respray if the pests return, if it rains, etc.

Or, if you want to make your own spray, the garlic spray is the classic home gardener's weapon against caterpillars and the like. There are literally dozens of recipes. I make a combined garlic/chilli spray. I toss a head of garlic, a couple of hot chillies, a couple of squirts of washing-up detergent, a glug of oil and 4 or 5 cups of water into a blender. Blitz, strain out all the solids, then add another cup of water. Pour it into a spray bottle with an adjustable nozzle, label it, and attack your pests. Again, it's only a contact spray. It doesn't have residual properties.

It's a bit pongy, but it works!

17/05/2012 at 20:52

How long would your spray keep for while still being effective.

17/05/2012 at 21:34

I make enough to last about six months before making more. It's still effective after six months.

22/05/2012 at 13:38

you are amazing you lot! i got the pyrethrum spray and have also made the garlic chilli spray. im armed and ready for action!! thanks so much everyone x

22/05/2012 at 16:36

Goodoh. Don't forget they're contact sprays. You have to hit the critters with the stuff and hit them again if they return. Neither spray has any residual effect.

23/05/2012 at 14:25

will do, thanks again 

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