HYMENOPTERA. 
Development. 
liberty, feeding on the foliage of trees; the latter are free, so far as they are not 
confined within an egg-membrane, but being internal feeders, whether in foliage 
larvae, wood, or shut up as solitary hermits, each in its several cell passes a larval 
period of limited freedom. It is a curious fact that the legs of some larvae are 
more evident in an early than in the latter stages, thus proving that the habit of 
cell-life is a comparatively recent departure from a former habit, when in all 
probability the larval life was passed in greater freedom. 
The phenomenon of parthenogenesis is one which crops up in 
various orders of insects, being simply the production by the female 
of eggs or young without the fertilisation of the egg-germs within the female, by 
the stimulative elements necessary to the production of young in the higher 
animals. It is not, however, a chance phenomenon, appearing as a race-preserving 
expedient, on the sudden failure of male forms, but one of nature’s resources for 
preserving the continuity of species. It is constant in many species of the 
Hymenoptera, in the form of what is known as the alternation of generations; in 
some species, however, it is supposed to be the sole form of reproduction, for the 
males of these species have never yet been discovered. Whether we regard 
the fertilisation of the female egg-germs by the male elements as dynamic or 
stimulative, or as merely a matter of the interchange of character determinants 
between the two sexes, it appears to be beyond a doubt that a continuous 
succession of virgin-reproductions must inevitably tend to the degeneration and 
ultimate extinction of the race. Parthenogenesis or virgin-reproduction may 
be of three kinds. First, resulting in the production of the male sex only; 
second, of the female alone; and thirdly, in cases when the young are produced 
not as eggs in the first instance, but alive, as in the case of the plant-lice or 
Aphidce. It seems that parthenogenesis does not favour the production of one 
sex more than another. We should, therefore, be cautious how we accept too 
hastily the commonly received belief that male bees are necessarily the offspring 
of non-fertilised eggs. It by no means follows that because an egg was not 
fertilised that therefore the sex produced in it is the direct result of non¬ 
fertilisation. The question, however, is still a matter of controversy, and more 
evidence is needed before final conclusions can be reached. 
That the members of this order are on the whole useful to man cannot be 
doubted,—more useful perhaps than the majority of insect forms,—whether as bees, 
with their honey-storing instincts, or as the ichneumon tribes dealing destruction 
to thousands of the larvae—those insect pests which would otherwise work terrible 
havoc with our corn crops and garden produce. On the other hand, it must be 
confessed that the larvae of the saw-flies often work damage to the foliage of 
forest-trees, while in many tropical climates ants are a devouring scourge to all 
that belongs to man. 
We must now leave these introductory lines, but before passing- 
on to a more or less detailed description of certain species and their 
peculiar characteristics of structure and of habit, the subjoined outline of classifica¬ 
tion of the various families of the order will give a general idea of the different 
groups, which are more obviously separated by certain broad distinguishing- 
characters. 
Classification. 
