Lecanicillium muscarium is the approved name of an entomopathogenic fungus species, that was previously widely known as Verticillium lecanii (Zimmerman) Viegas), but is now understood to be an anamorphic form in the Cordyceps group of genera in the Cordycipitaceae.

Insects are infected when they come into contact with the sticky fungal spores which then grow and invade the body, thus the internal organs are consumed, leading to their death.

In horticulture and agriculture, the Lecanicillium muscarium isolate (isolate GCRI 19–79) was first developed by scientists, Drs Richard A Hall and HD Burges[4] at the Glasshouse Crops Research Institute (now Warwick HRI: formerly part of Horticulture Research International).

L. muscarium isolate Ve6 (GCRI 19–79; IMI 268317; ARSEF 5128; CBS 102 071) is marketed as 'Mycotal' and has been re-registered in the EU:[5] especially for control of whiteflies such as Trialeurodes vaporariorum and thrips by Koppert in the Netherlands,[6] who provide good illustrations of the fungus.

Other products, possibly based on this fungus have been developed elsewhere for use in cash crops, oil seeds, soybeans, ornamentals and vegetables.