Heterogenea asella
The triangle is a species of moth of the family Limacodidae. It is found in most of the Palearctic realm.
The wingspan is 15–20 mm. Adults are on wing from the end of May to mid July in one generation per year.
Image:Buckler W The larvæ of the [British butterflies and moths PlateLIII.jpg|thumb|140px|left|Figs. 7, 7a adult larva slightly magnified 7b adult larva natural sixe on beech leaf also the cocoon]
The larvae feed on Acer, Corylus, Fagus and Quercus species.