Page:Darwinism by Alfred Wallace 1889.djvu/280

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258
CHAP.
DARWINISM

found at Chontales. The pretty longicorn, Callia albicornis, closely resembles two species of malacoderms (Silis chalybeipennis and Colyphus signaticollis), all being small beetles with red head and thorax and bright blue elytra, and all three have been found at Panama. Many other species of Callia also resemble other malacoderms; and the longicorn genus Lycidola has been named from its resemblance to various species of the Lycidae, one of the species here figured (Lycidola belti) being a good mimic of Calopteron corrugatum and of several other allied species, all being of about the same size and found at Chontales. In these cases, and in most others, the longicorn beetles have lost the general form and aspect of their allies to take on the appearance of a distinct tribe. Some other groups of beetles, as the Elateridae and Eucnemidae, also deceptively mimic malacoderms.

Wasps and bees are often closely imitated by insects of other orders. Many longicorn beetles in the tropics exactly mimic wasps, bees, or ants. In Borneo a large black wasp, whose wings have a broad white patch near the apex (Mygnimia aviculus), is closely imitated by a heteromerous beetle (Coloborhombus fasciatipennis), which, contrary to the general habit of beetles, keeps its wings expanded in order to show the white patch on their apex, the wing-coverts being reduced to small oval scales, as shown in the figure. This is a most remarkable instance of mimicry, because the beetle has had to acquire so many characters which are unknown among its allies (except in another species from Java)—the expanded wings, the white band on them, and the oval scale-like elytra.[1] Another remarkable case has been noted by Mr. Neville Goodman, in Egypt, where a common hornet (Vespa orientalis) is exactly imitated in colour, size, shape, attitude when at rest, and mode of flight, by a beetle of the genus Laphria.[2]

The tiger-beetles (Cicindelidae) are also the subjects of mimicry by more harmless insects. In the Malay Islands I found a heteromerous beetle which exactly resembled a Therates, both being found running on the trunks of trees. A longicorn (Collyrodes Lacordairei) mimics Collyris, another genus of the same family; while in the Philippine Islands

  1. Trans. Ent. Soc., 1885, p. 369.
  2. Proc. Cambridge Phil. Soc., vol. iii. part ii., 1877.