Is it worth spending money on a biological control at this time of year? they are on my aubergines and peppers in the greenhouse and my herbs in the kitchen, but I think the nematodes attack the larvae rather than the flies. Is there any other cure?
Are your plants in pots or planted in the ground? If in pots try submersing the pots in a bucket of water for 24-36 hours in an attenpt at drowning the offfenders. (roots in water, foliage out of water)
I tried this with a potted young grape vine this week, attempting to control vine weevil. After all neither of these insects live in lakes do they ;)
They are in pots, so I'll have a go!