The feet of the beetle Hemisphaerota cyanea grip hard on waxy palmetto leaves by having thousands of contact points (bristles) wetted with oil.

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The author noticed that when he tried to pick this beetle off of a palmetto leaf, he had to exert considerable force to pry them loose. "What the beetle does have on its feet is bristles, thousands of bristles, sticking out from the sole of each foot--the ventral tarsal surface--like hairs on a brush. Bristles are a common feature of beetle tarsi generally, but I had never seen them in such quantity per footEach tarsus was subdivided into three bristle-bearing subsegments, called tarsomeres. We counted the bristles and found that there were about 10,000 per tarsus, making a total of 60,000 per beetle. Each bristle was forked at the tip, which means, if we assumed the bristle endings to be the contact points with the substrate, that the beetles had the option of relying on 120,000 such pointsThe bristle endings of H. cyanea did indeed turn out to be padlike, and they were wettedWe now know that fluid is an oil, consisting of a mixture of long-chain hydrocarbons (specifically C22 to C29 n-alkanes and n-alkenes). An oil is ideally suited to secure adhesion to a leaf, since the outermost surface of leaves is waxy (palmetto fronds are no exception), and waxes make good contact with hydrocarbons." (Eisner 2003:134-135)

Book
For Love of InsectsThe Belknap Press of Harvard University PressOctober 31, 2005
Thomas Eisner

Journal article
Structural design and biomechanics of friction-based releasable attachment devices in insectsGorb, SN; Beutel, RG; Gorb, EV; Jiao, Y; Kastner, V; Niederegger, S; Popov, VL; Scherge, M; Schwarz, U; Votsch, W

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