Black insects ? What are they...

murihikukid · October 3, 2016

Hi..I am growing tomatoes inside under lights and yesterday removed most of my lights...This revealed that above my tomatoes on my ceiling were a lot of cobwebs and in these cobwebs were a lot of black bodies so I have taken photos and posted them....Now these insects are not in cobwebs any where else in the house and rarely do I see one flying around but I do see a light fawn coloured insect flying around now and then...

I have checked my soil and under the leaves and surely I would see them them if they were there so where do they come from...I just do not know ...Could they come through from above the ceiling? or in my freezer shells that hold the drums with my plants in them and the soil is heated underneath by hot air coming from a panel heater on a thermostat ....and are they killing my plants with disease....

Hopefully somebody has seen such insects although one is an oddball and looks more like a mossie but then again it may not be....

Thanks for any help solving this problem and what to do about it...

Thanks Ron...

Perennial Guru · October 13, 2016

It's a bit challenging to know for sure, but it looks like at least some of these insects are fungus gnats and some are shore flies. These are both fairly common in container grown plants, and their eggs can sometimes be found in potting mixes. They live in the soil as larvae and grow especially well in wet soil conditions.

They occasionally build up to large enough numbers that the larvae can cause some damage by feeding on plant roots, but they are usually just a nuisance. Populations can usually be reduced with good moisture management and letting the soil dry out between waterings.

Adults can be monitored and controlled with yellow sticky card traps. Larvae can be controlled by drenching the soil with a neem oil product if populations get overly high.

brownrexx · October 13, 2016

A good way to control fungus gnats is to freeze your potting soil or soiless mix before using. I put mine outside during the freezing winter temperatures for a day or two to kill the eggs that are in the soil.

If you have fungus gnats in the soil you can kill them by watering with a bt solution. Mosquito Dunks are a product made to use in water to kill mosquito larvae and they work on fungus gnat larvae too although in my opinion the freezing option works better. I have not had any fungus gnats since I started doing this.

murihikukid · October 14, 2016

Hi...Thankyou for your replies ...very interesting.... Thanks Ron

October 13, 2016	#2
Perennial Guru Tomatovillian™ Join Date: Sep 2016 Location: WI Posts: 5	It's a bit challenging to know for sure, but it looks like at least some of these insects are fungus gnats and some are shore flies. These are both fairly common in container grown plants, and their eggs can sometimes be found in potting mixes. They live in the soil as larvae and grow especially well in wet soil conditions. They occasionally build up to large enough numbers that the larvae can cause some damage by feeding on plant roots, but they are usually just a nuisance. Populations can usually be reduced with good moisture management and letting the soil dry out between waterings. Adults can be monitored and controlled with yellow sticky card traps. Larvae can be controlled by drenching the soil with a neem oil product if populations get overly high.

October 13, 2016	#3
brownrexx Tomatovillian™ Join Date: Feb 2016 Location: Southeastern PA Posts: 1,420	A good way to control fungus gnats is to freeze your potting soil or soiless mix before using. I put mine outside during the freezing winter temperatures for a day or two to kill the eggs that are in the soil. If you have fungus gnats in the soil you can kill them by watering with a bt solution. Mosquito Dunks are a product made to use in water to kill mosquito larvae and they work on fungus gnat larvae too although in my opinion the freezing option works better. I have not had any fungus gnats since I started doing this.

October 14, 2016	#4
murihikukid Tomatovillian™ Join Date: Feb 2016 Location: Invercargill New Zealand Posts: 1,022	Hi...Thankyou for your replies ...very interesting.... Thanks Ron