The White Shoulderd House Moth (Endrosis sarcitrella) is a very common moth and occurs regularly inside buildings, and being continuously-brooded, can be found at any time of year, mainly found indoors via open doors, windows etc...
The Caterpillar is small and grub like and lives on dried plant and animaldebris. This is the reason why the species has been accidentally introduced into many parts of the world. With dried stored goods.
