Leatherjacket Killer 500 square metres contains 250 million Steinernema carpocapsae nematodes. These nematodes are watered into lawns or grass areas, where they seek out & infect Leatherjacket larvae. Once the nematodes enter the larvae, they release a bacteria, which kills the grub. The body is then used as a breeding site for more nematodes. It is important to apply with plenty of water & irrigation to make sure the nematodes can enter & move through the soil. Avoid application in bright & sunny days, as nematodes are U.V sensitive. (Please note: We regret that this item is not available to customers living in Eire.)