COLEOPTERA > POLYPHAGA > CHRYSOMELOIDEA > Chrysomelidae > Cassidinae

A distinctive group of beetles that, apart from their colour and/or markings, are all very similar with a broad, rounded and flattened shape, and a head that is completely hidden beneath the pronotum. The antennae are placed close together and are gradually thickened, but never clubbed. Most species are yellow or green, unmetallic, and well camouflaged. There are two notable exceptions, which are the mature form of Cassida murraea and the beautiful Pilemostoma fastuosa beetle, both of which are red and black.

Whilst fourteen species of tortoise beetle have been recorded in Britain, one is almost certainly extinct. The remainder, apart from Pilemostoma fastuosa, which is a scarce and sporadically recorded southern species, are all members of the Cassida genus (meaning helmet in Latin).

The most common and widespread species are the two grassland thistle tortoise beetles Cassida rubiginosa and, although far less frequently recorded, Cassida vibex. The distribution data for the remaining species leads me to believe that Cassida flaveola (Pale Tortoise Beetle), Cassida murraea (Fleabane Tortoise Beetle), Cassida viridis (Green Tortoise Beetle) and possibly Cassida nebulosa are the only ones that I could encounter locally.

Cassida rubiginosa is green or yellowish-green, often with brown markings on or around the scutellum, and distinctly oval in shape with a more or less continuous outline. It is by far the most frequently seen and recorded tortoise beetle species across much of the country. The species is strongly associated with thistles, hence the common name of Thistle Tortoise Beetle.

Cassida murraea is green, turning reddish-orange when fully mature, with small black spots or blotches especially along the elytral suture. They average 6.5-9mm long and typically occur in damp habitats where their host plants, Common Fleabane and Marsh Thistle, can be found. Despite being regarded as locally common in the south west, the NBN Atlas shows that nearly half of the recorded sightings have been from South Wales. I was encouraged that Dorset was second on the list but, when I checked, there were only 55 records across the whole of the county.

Updated, Oct.22 (v.2)