Agonopterix assimilella is a moth of the family Depressariidae. It is found in most of Europe.
The wingspan is 15–21 mm. The forewings are whitish-ochreous, often mixed with deeper ochreous or brownish, strewn with dots of blackish scales; first discal stigma blackish, second whitish, but usually obsolete, sometimes preceded by a reddish mark, across which lies often an oblique dark fuscous suffusion. Hindwings are ochreous-grey-whitish. The larva is brown; dots black; head and plate of 2 black.[1]
Adults are on wing from April to June.
The larvae feed on Cytisus scoparius. Larvae can be found from October to February.[2] The species overwinters in the larval stage within the stem.[3]
A. assimilella has been introduced to New Zealand to attempt to control the invasive to New Zealand plant Cytisus scoparius.[4] As at 2021 the success of the introduction of this species to New Zealand was uncertain.[5]