18

Beetle anatomy

EXAGGERATED STRUCTURES

The Asian Atlas Beetle Chalcosoma (Scarabaeidae:

Dynastinae) is a rhinoceros beetle where the male

has three long, curved horns, one on the head and

two on the thorax, and is a glossy metallic color.

Males in the breeding season are conspicuous,

flying around streetlights in tropical towns

in Malaysia or Indonesia, and it is surprising

that they can fly at all with their extreme

ornamentation. If two males meet, they

immediately compete, sizing off against each

other, or grappling and pushing each other

with their moveable cephalic horns until one

is defeated. Although it impressed Darwin,

and would impress most observers, the

purpose of this extravagant display is to

impress the female Chalcosoma, which is a dull

brownish color and lacks any horns, is rarely

seen, and does not display, but instead maintains

a low profile among tangled vegetation. The

females safeguard the future of the species, as the

majority of males will never reproduce and, for

all their extravagance, are the expendable sex.

The extreme decoration of the males is also

maintained and passed to the next generation by

the females, since females preferentially reproduce

below | Phanaeus demon (Scarabaeidae)

A suitably demonic-looking male of the

Central American rainbow dung beetle

showcases many exaggerated structures.

opposite | Cyclommatus

eximius (Lucanidae) The male

of this New Guinean stag

beetle has huge mandibles.

The female has no such

ornamentation.

below | Sagra buqueti

(Chrysomelidae)

The Frog-Legged Beetle

from tropical Asia is,

paradoxically, unable to

hop with its huge back legs.