The larva of the gall midge Taxomyia taxi causes galls to form on Yew (Taxus baccata).  The gall comprises of 60 - 80 terminal leaves that become clustered to form a single artichoke type gall whose outer leaves are dark green and the inner ones almost white.  An orange larva or pupa is inside.  The galls eventually turn brown and can stay on the plant right through to the next year.

Gall  Adult

Each gall contains a single orange-red larva that feeds within the gall after a resting period and then pupates inside and emerges as an adult about 1 month later.

Occasional in England and Wales, but may well be quite common and under recorded.

Fairly frequent