170 
HYMENOPTERA. 
Other factors probably are the very great specialization insects 
display; we may imagine a caterpillar, if omnivorous and without 
enemies, growing to the limit of the size that its chitinous legs, and 
prolegs could bear ; it might perhaps be six feet long and a foot high, 
walking along like a vast worm and browsing happily in the pasture. 
But there are no omnivorous caterpillars (plants protect themselves 
too well with poisons and other devices), the vast number and variety 
of species are correlated with great specialisation and whether from 
the limitations of chitin, or from the difficulties of metamorphosis, 
such vast creatures do not exist. 
Possibly insects are dominant because they are small, reproduction 
can be quick and vast, an egg can contain enough food to produce an 
active self-supporting larva ; the difficulties of viviparism are avoided 
and the mother need not live over to care for her young. When the 
seasons are unfavourable, the female waits with her store of undeve¬ 
loped eggs till the season is favourable. Above all, where there is one 
vast animal like a cow, conspicuous and slow breeding, you may have, 
in equal bulk, a horde of scattered insects, ready to concentrate 
themselves on one point but capable, in times of stress, of diffusion 
over wide areas and in inappreciable amount. It is the case of the 
fly which eats the carcase quicker than the lion, because the concen¬ 
trated effort and increase of a thousand small creatures outweighs the 
efforts of the one large creature a thousand times their size. 
The insect, with the lion, endures times of starvation but of a 
thousand, perhaps, ten insects survive, whereas the one lion dying leaves 
none. So that taking lives as units, the small insect is better off and 
it may be that in the very limitations of chitin and metamorphosis has 
lain its success, since strivings after mere bulk have been vain where 
natural effort at increase, with multiplication of species and function, 
has enabled the insect to overrun and dominate the earth. 
Dryinim. 
Female with the foreleg modified to form a pineer. 
A family of nearly 200 species of small insects, usually included in 
Proctotrypidce , and distinguished by the fact that the fore tarsus is 
modified in the female to form a pineer. 
This modification of the foreleg is connected with the habits of the 
insect; according to Ivieffer, the female seizes the nymph of the Homop „ 
terous insect she attacks by means of the pincers, and lays one or two 
eggs in its abdomen ; the resulting larva develops, emerges and 
pupates outside, the Homopterous nymph dying. Three species only 
are known from India : Dryinus trifasciatus, Kieff., Prodryinus 
bifasciatus, Soy., and Gonatopus maurus, Kieffer. 
