Platyptilia isodactylus

The wingspan is about 19–29 mm. The wings are pale fawn or brown in colour with dark bands at the ends and variable V or double V shaped dark brown bands approximately one third of the wing length from the wing tip. The body and legs are lighter brown. The forewing is divided into two lobes and the hindwing into three feather-like plumes. The middle and hind legs are very long and have prominent spines. Adults have a characteristic resting posture with the body and fully outstretched wings forming a T shape, the forewing covering the hindwing, and the hind legs raised and extended parallel with the body. Males have longer, thinner abdomens.

There are two generations per year with the moths active in spring and autumn. During their lifetime, which is around twelve days, females lay an average of one hundred eggs. The newly hatched larvae, initially live free under a rosette of leaves, before boring into the stem.[2] The larvae pass through five instars and the older larvae tunnel in the crown, stem and roots. Larvae eject their frass and shed head capsules from a small hole in the stem and this debris accumulates on silken webbing spun around the hole by the larva. Occupied stems are stunted, can be strongly curved and often die above the feeding area.[2] Food plants include common ragwort (Senecio jacobaea), marsh ragwort (Senecio aquaticus), Senecio nemorensis, groundsel (Senecio vulgaris) and broad-leaved ragwort (Senecio sarracenicus).[2]

The pupal stage lasts about one week.

It is native to central Europe, Mediterranean North Africa and southern Europe. It has also been recorded from China.[3] It has been introduced in Australia as a biological control agent for ragwort.

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• Fact Sheet
• Biological Control of Ragwort