Plague of the black ants in greenhouse :(

[Louis]

I have beat the mites, gnats and now i am deluged with black ants in the greenhouse. i find them everywhere, mostly in the blooms where they are feasting on nectar. i do not have aphids which would account for some ants.

i have tried ant traps and they make no difference.

any ideas how i can get rid of them. charlie, do you have this problem??

louis

[Charlie]

Hi Louis,

Ants have to watched out for since they will farm any of the sap sucking insects including mealybugs that you do not want to get on your hibiscus. I have found that ants absolutely hate the pyrethroid family of pesticides. These are those originally derived from the natural pesticide that is found in Chrysanthemum plants. California ants won't cross over a barrier of pyrethroid spray around the perimeter of a greenhouse nor enter an area if that area has been sprayed with pyrethroids. Unfortunately, the effect wears off in about 2 weeks and has to be reapplied. Pyrethroids are commonly used in ant sprays that you can buy anywhere. If you can find where they are entering the greenhouse you can just treat around that limited area but if not then spray anywhere you do not want them to walk over and they won't until the stuff wears off.

Baits should work given enough time so a good strategy is to use the pyrethroids to keep the ants out and place the baits outside of the spray perimeter.

Charlie

[blupit007]

Charlie, how dangerous is this stuff?  I have carpenter ants that parade out deck constantly all summer.  I also have 2 bunnies that live loose on the deck, so I never wanted to spray anything. (bunnies chew...)  I have never seen the ants on my hibiscus though which is good.

[Charlie]

Some people consider pyrethrum, which is the natural plant based form, as one of the least problematic of the pesticides. Once it is altered in the lab to become one of the pyrethroids it is more potent and is effective longer. They all break down relatively quickly. There's no danger to mammals that might walk over the area after it is sprayed and dried. There is a smell to this type but it diminishes quickly and some are less smelly than others.

Charlie

[roadrunner]

Charlie I've had a problem for the last few years with at least 3 different species of very tiny black ants that like to nest in the containers.  This has mostly been a problem with potted plants out in the landscape but also at times inside the greenhouse and briefly last winter in the house.  My roses have been the main target but any hibiscus in containers outside in the landscape will be infested shortly after they're moved back outside.  These ants appears to be aphid herders. I've tried powders and a pyrethrum based liquid with some success but it has only been temporary.  I wonder if a systemic drench like Tree and Shrub with Safari that kills the aphids would discourage the ants from nesting in the pots since their food source would be gone, or could the drenching of the soil in the pot possibly kill the ants as well?  It's been a never ending battle similar to fighting spider mites. 

dave

[Charlie]

That's a good question, Dave. I'd try the Safari and see what happens. Cindy says she had some success spraying the surface of her pots with limonene but I always use a pyrethroid and it works well for up to 2 weeks. No permanent solution for ants, I'm afraid, as the earth seems to be one giant anthill.

Charlie