Lasiocampa trifolii, the grass eggar, is a moth of the family Lasiocampidae first described by Michael Denis and Ignaz Schiffermüller in 1775 and found in Europe.

[1][2] Eggs are laid on leaves close to the ground, hatch in the autumn, and the young larvae hibernate.

The larvae feed on grasses,[1] various shrubs and deciduous trees, such as oak, European beech, poplar and Calluna.

[citation needed] The cocoon is formed on the ground.

[1] Adults' wingspan is 40–55 mm and it flies from June to September depending on the location (in Britain it is on the wing in August).