Defense by foot adhesion in a chrysomelid beetle (Hemisphaerota cyanea): characterization of the adhesive oil

The beetle Hemisphaerota cyanea, when disturbed, secures a tight foothold o n the substrate, whereby it is able to resist pulls of upward of 200 times its body mass. The grip is mediated by thin film adhesion, through use of a n oil, which wets the contact pads at the tips of the 60,000 tarsal bristle s of the beetle. We have found the oil to consist of a mixture of C-22 to C -29 n-alkanes and n-alkenes, providing additional support for the notion th at tarsal oils are mixtures reflective of the general cuticular hydrocarbon output of insects.