The present invention provides insecticidal lipids and lipid fractions from fungi of the phylum Ascomycota, together with compositions comprising such lipids and lipid fractions and methods of preparing same. Methods for the biological control of insects, such as phytopathogenic insects, using the lipids and lipid fractions or compositions comprising said lipids optionally together with one or more insecticidal or entomopathogenic agents including entomopathogenic fungi, are also provided.