Thrip Infestation

[Roger]

Hello all!  About a week and a half ago I noticed a few brown flying bugs.  I didn't think much of it.  I put out two yellow sticky traps and then have been gone since on vacation.  Upon my return home last night the few bugs I initially noticed have turned into hundreds.  After some research today I've finally diagnosed the bugs as thrips.  What can I do to control these?  I generally use AzaMax on my hydro systems but am worried the active ingredient, azadirachtin, from the neem tree will harm the fish.  Any other suggestions besides sticky traps?  These buggers also seem to have transmitted Tomato Spotted Wilt Virus to my tomatoes, peppers, and cucumbers.  From what I've read once the plants have this virus there is nothing you can do.  

I've almost thought about pulling all plants from the system, but am worried that this would cause a nitrate spike since the replacement plants I have are still pretty much seedlings.  Any thoughts?  I have a 100 gallon reservoir with 20 Blue Nile Tilapia.

Thanks for any advice anyone can pass along.  I don't want to kill my fish but I really need to get rid of these buggers!

[Roger]

Anyone have any answers for my questions?  I believe I'm going to have to pull all the plants.  I'm just worried about how this change will affect my fish.

[Jana harris]

Aren't there some beneicfical insects you can use for thrips? Can you use a diluated molasses spray on the under side of the leaves? Sometimes the use of a oscilating fan can help deter some insects.

 

Jana

 

[Jana harris]

Pirate bugs and blue sticky trapps
 
Jana harris said:

Aren't there some beneicfical insects you can use for thrips? Can you use a diluated molasses spray on the under side of the leaves? Sometimes the use of a oscilating fan can help deter some insects.

 

Jana

 

[Matt T.]

The nematode Steinernema feltiae will attack larvae when srayed. There is also the predatory mite Amblyseius cucumeris. They are also effective against Fungus gnats, but expensive....

[Tony Dyson]

Hi Roger,

A flour preparation can be used against Aphids and Spider mites, Flour and soap can also be used against Thrips, Whiteflies and downy mildew on cucumbers in greenhouses.

I found the following that may be of interest to you! Flour mixed in water is said to be very effective against aphids and spider mites. It should be applied in the morning taking care to spray underside of leaves, as the heat of the sun increases, the mixture dries out and the insects are left encrusted in flour, shrivel and die. The coating of flour falls off the leaves so that their ability to photosynthesise is not essentially affected (Stoll 1988).

According to Ellis and Bradley (1992) starch like ordinary baking flour is an old pest control remedy, potato starch apart from killing aphids, red spider mites, white flies and thrips also acts as an inhibitor to downy mildew on cucumbers in glasshouses.

Flour and Soap recipe:

Add 2 - 4 tablespoons of wheat or potato or any plain baking flour into 1 Litre of warm water, stir well add a dash of liquid soap to act as a surfactant, stir the filtrate again prior to a spray application.

Regards

[Matt T.]

Thanks for the heads up Randall. I was wanting to ask someone about a forum on the subject. I will also ask Sylvia tonight about her feelings on introducing benificial bacteria to systems. See you on the Pest forum.

[Roger]

Thanks for all the information everyone!  I do have some Spinosad but was worried it would harm my fish.

[Rich File]

I noticed a thrip infestation last week and got some Spinosad (Monterey) today. I applied it to the plants outside of the flood plain and am going to shut the water flow down for 12 hours. I'm sure a bit dripped into the fish tank and so far no dead fish, fortunately. 

[Alex Veidel]

Rich, spinosad has a minimal effect on water quality; it's quite safe for fish as long as you don't overdo it. But, it's always good to be conscious of overspray.

Rich File said:

I noticed a thrip infestation last week and got some Spinosad (Monterey) today. I applied it to the plants outside of the flood plain and am going to shut the water flow down for 12 hours. I'm sure a bit dripped into the fish tank and so far no dead fish, fortunately. 

[Rich File]

Hey Alex, I haven't lost any fish. I did suddenly lose two leopard frogs who for whatever reason escaped from the flood plain and later died. It could be pure coincidence, but I suspect they may have found the bacteria irritating and fled.

Alex Veidel said:

Rich, spinosad has a minimal effect on water quality; it's quite safe for fish as long as you don't overdo it. But, it's always good to be conscious of overspray.

Rich File said:

I noticed a thrip infestation last week and got some Spinosad (Monterey) today. I applied it to the plants outside of the flood plain and am going to shut the water flow down for 12 hours. I'm sure a bit dripped into the fish tank and so far no dead fish, fortunately. 

[David Wilcoxson]

I have tried several methods to rid greenhouse of whiteflies.  The oil sprays e.g.Ladybug spray end up making vegetables like lettuce taste bitter.  Soap sprays are high in potassium which could be harmful to the fish.  I have finally settled on using a shop vac with a long hose in morning and in the evening.  My plants are no longer dying, and  I have gone from vacuuming tens of thousands of flies, down to a few hundred a day.  Beneficial insect helped, but they do not seem to survive long, and have not reproduced.