I have a little fungus gnat problem, I have re potted all my cacti (roots were washed thoroughly and left in sun for a couple of days) , put sticky traps around and added mineral rock to the surface but still haven't conquered them.

will Hypoaspis Miles (predator insect) damage the cacti once the larvae are eradicated?

will they be able to penetrate the soil with the thick layer of mineral rock I have put there?

will they attract other pests?

Cheers

Hi San Rainbow.

I have used Hypos a few times for controlling fungus gnats with varying levels of sucess. To answer your questions the hypos will do no damage what so ever to your plants. They have no problem getting through the top layer of rock to the soil. I have no idea if they attract other pests I have had no problems with it.

Now a few things to note. The Hypos are not 100% effective at killing off gnats, gnats have a much more refined breeding cycle and it is possible for them reproduce faster than the mites will kill them off. That said Hypos will dramatically reduce the populations of fungus gnats but it will take about 2 weeks for them to get established and their numbers up.

It sounds like your taking the right steps so far. If you still have no sucess you may want to look at insecticides, yes they are chems buy they also work very well.