The Descent of Man

187.) enclosed two males with one female in a
box, the larger male severely pinched the smaller
one, until he resigned his pretensions. A
friend informs me that when a boy he often put
the males together to see them fight, and he
noticed that they were much bolder and fiercer
than the females, as with the higher animals.
The males would seize hold of his finger, if
held in front of them, but not so the females,
although they have stronger jaws. The males of
many of the Lucanidae, as well as of the abovementioned
Leptorhynchus, are larger and more
powerful insects than the females. The two
sexes of Lethrus cephalotes (one of the Lamellicorns)
inhabit the same burrow; and the male
has larger mandibles than the female. If, during
the breeding-season, a strange male attempts to
enter the burrow, he is attacked; the female
does not remain passive, but closes the mouth
of the burrow, and encourages her mate by
continually pushing him on from behind; and
the battle lasts until the aggressor is killed or