Sorry, but Malathion at spray strength will kill sciarid flies and arvae[ for the latter water into compost] they can be a problem for me as I grow carnivorous plants and they love the damp/wet peaty compost or you can fumigate glasshouses with nicotine, HCH or dichlorvos if available. Steve. . >I don't think malathion is effective on the larvae. I may be wrong.