immature sevuality in Insects. 197 
Dr. Landois, who has never, so far as I know, stated 
any clear and obvious facts incorrectly, although he 
has, unfortunately, drawn some very erroneous infer- 
ences, states very clearly that, when he half-starved his 
larvee, males only were produced, but that when well-fed, 
there were many more females than males. Whatever 
the explanation may be, I am strongly inclined to give 
credit to the fact. 
I mention these facts, because I believe that certain 
cutaneous appendages, as the gigantic mandibles and 
thoracic horns of many males, are complimental to the 
sexual organs. That, in point of fact, they are produced 
by the excess of nutriment in the male, which, in the 
female, would go to form the generative organs and ova. 
It may be urged that this is an improbable explanation, 
but it does not appear so to my mind, when we remem- 
ber the large amount of the generative product in the 
female, compared with that produced by the male. 
I think it may be noticed, that all those msects which 
exhibit the cutaneous horns and great mandibles in 
the male, feed on wood and other vegetable substances, 
or decaying animal matters that afford a very limited 
amount of nutriment, which necessitates the laying by of 
great stores of nutriment by the female for the after- 
nourishment of her ova.* The males usually exhibit 
two tolerably distinct forms, one with very large mandibles 
or horns, and another with these organs scarcely larger 
than those of the female in the case of the mandibles, 
and very small in the case of thoracic horns, or other 
structures absent in the other sex. 
It has occurred to me, that the males with the large 
cutaneous appendages may be those which are bred and 
nourished with the females, whilst those with the smaller 
horns may have been nourished by food not sufficiently 
nutritive to produce females. Hence the small horned 
males would have fewer offspring than the long-horned 
males ; and the horns would tend continually to mcrease 
in size, although under bad or poor feeding in the larval 
condition, they may frequently be considerably reduced. 
I very much doubt if the theory of ornament and sexual 
selection can be applied to beetles, owing to the very 
* These are chiefly developed from the great fat bodies of the female. 
TRANS. ENT. soc. 1871.—partT nm. (May.) P 
