Original paper
Zum Faltungsmechanismus der Hinterflügel einiger Blatthornkäfer (Coleoptera: Scarabaeidae)
[The Folding Mechanism of the alae of Chafers (Coleoptera: Scarabaeidae)]
Schneider, Peter
Entomologica Germanica Band 1 Heft 3-4 (1975), p. 232 - 248
15 references
published: Jun 30, 1975
DOI: 10.1127/entom.germ/1/1975/232
ArtNo. ESP346000103002, Price: 29.00 €
Abstract
The folding mechanism of the alae of the cockchafer beetle (Melolontha melolontha Linné 1758), rhinocerous beetle (Oryctes boas Fabricius 1775) and a maroccan pill-roller beetle (Scarabaeus spec. ) was examined through film analysis and observation of living insects, as well as through the manipulation of dissected thorax specimens: At the beginning of the longitudinal folding of the retracted alae, this process is supported by the correspondence of the epipleura and costal hair fields of the closed elytra with the hairs of the costal veins of the alae. It is facilitated further by the interior space of the closed elytra, creating a negative form into which the alae are inflected in the region of the costa-subcosta, in front of the marginal joint. Facilitated by pressure created through pumping movements of the abdomen, the alae are formed into transverse folds radiating from the marginal joint. During this procedure, the closed elytra serve as abutment against the movement of the abdominal tergits. Deviating from this type, the Scarabaeini fold both alae simultaneously, rotating the wing tip upward along a longitudinal fold behind the radial vein. This movement creates two temporary transverse folds, which are pushed toward the wing tip during the bending of the marginal joint. Through this procedure, both alae mutually create an abutment. - With the unfolding of the alae, a blood pressure change, possibly created by the abdominal pumping movements during flight preparation, can be noticed. It might serve as an antagonist to the elastic characteristics of the marginal joint and indurated fields of the alae. During the folded state, the alae are inactive, and require no special mechanism to be kept in this position.