Species Cassida rubiginosa - Thistle Tortoise Beetle

Bloody-nosed Beetle

from the Latin "rubiginosus" (rusty; rust-colored; reddish-brown); supposedly refers to the beetle's ability to secrete a reddish liquid from its head, giving rise to its other common name of Bloody-nosed Beetle [source: anonymous reference from Ireland]

adult length 6 to 7.5 mm

Adult: body oval, convex (as in other tortoise beetles); carapace green in live individuals - completely fading to brown or yellowish in dead specimens; small double depression in surface of each elytron midway along anterior margin, usually marked by two dark spots, or sometimes with more extensive dark shading; anterior margin of both elytra collectively forms a very shallow concave arc when viewed from above - shaped more like a rounded bracket than a brace bracket; medial and inner areas of each elytron covered with small punctures but not deeply pitted

undersurface completely black; femora black; tibiae and tarsi brown or brownish-orange

Larva: oval, brownish or greenish, with dark branched spines around perimeter, and a forked tail spine on which it accumulates moult skins and excrement (these are held as a protective parasol over the insect's back)

native to the Palaearctic Region(1); accidentally introduced in PQ in 1901, and has since spread east to NB, west to AB, and south to n. US; intentionally introduced to VA to control thistles

weedy fields and waste places where food plants grow

larvae and adults may be present from spring through fall

various Asteraceae, incl. several thistle (Carduus, Cirsium, Onopordum) and knapweed (Centaurea) spp.(1)

one generation per year; overwinters as an adult in soil litter; beginning in spring, up to 1,000 eggs are laid on the underside of leaves in cycles of approximately 6 weeks, with 7-week rests; adult life span is about 80 weeks, with an egg to adult developmental period of 6 weeks

This species has been used in biological control of thistles. It can reduce thistle vigor and survival, particularly in vigorous grass, but its impact is usually restricted by parasitoids.

Author of this species is Müller, 1776.

C. flaveola has a more extensive distribution (extending to BC YK NT in the west and north), the medial and inner areas of each elytron extensively pitted, the anterior margin of both elytra collectively forms the shape of a brace bracket with pointed tips projecting forward, and the color of live individuals is supposedly more yellow [based on the meaning of the species epithet, but no Internet photos were found to confirm this]