Thistle tortoise beetle
The thistle tortoise beetle (Cassida rubiginosa) is a species of leaf beetle, situated in the subfamily Cassidinae (tortoise beetles) and the genus Cassida. Description Cassida rubiginosa measures 6.0–8.0 mm in length. Like all Cassida its head is covered by the pronotum and the elytra has a wide flange surrounding it. This species is highly rounded, with green or yellowish-green elytra, sometimes with a small dark triangular spot around the scutellum. The common name may be misleading for the identification of this species as "rubiginosus" is Latin for "rusty or rust-coloured"). Male copulatory apparatus As in many small beetles, the male sex organ of C. rubiginosa is actually longer than its body — the organ is also very thin and curved at the end. The beetle needs such an organ because of the shape of the female reproductive organ, which includes a coiled duct that the male must penetrate. These physical properties have been studied because the ability of a thin, flexible structure to penetrate without buckling or rupturing is mechanically challenging and may have important implications for the development of microscopic catheters in modern medicine. Distribution The thistle tortoise beetle is native to Eurasia and has been recorded in Britain.