80 MODERN CLASSIFICATION’ OF INSECTS. 
same fact. Hence, the various forms observable in the structure of the 
mouth of these insects, notwithstanding the uniformity of the nature of 
their food, are dependent upon the form of the flowers from which the 
nectar is procured; the means by which it is prepared and transported 
either for food or for store for the future young ; and the various modes 
in which the different parts of the mouth are employed in the construc- 
tion of the nests. For instance, if a flower be long and tubular, it is 
necessary that the tongue should be elongated and slender ; whereas in 
those species which collect the honey from shallow or flat flowers, the 
tongue is shortened. In those species, again, which collect honey for 
store for their young, the tongue and its appendages are of large size ; 
whereas in those which need only a very small supply of honey for 
their own support, it is short and narrow. The form of the mandibles, 
again, is entirely dependent upon the mode of construction of the nest, 
serving as trowels, rasps, &c. The order is also anomalous, from com- 
prising species which are composed of three kinds of individuals, 
namely, males, females, and neuters. The latter occur in no other 
order of insects except in the single Neuropterous family Termitide ; 
and as they exist only in the social species, where a great share of the 
labour of the community is cast upon a certain portion of the inha- 
bitants, it is necessary for the due performance of the labour by the 
latter, that they should not interfere with the duties of the individuals 
occupied in continuing the race ; and their sexual organs and instincts 
are accordingly rendered singularly abortive. In all other respects 
they are females, These peculiarities will however more properly 
obtain notice under the respective families. The duration of the 
existence of these insects never exceeds one year, there being only 
one generation during that period. 
This order is of very considerable extent, being apparently inferior 
only to the Coleoptera. Messrs. Kirby and Spence have estimated the 
number of its species as averaging about one fourth of the insect po- 
pulation. In this country we probably possess 3000 species, of which 
two thirds are of minute size. These insects, judging at least from the 
number of large species sent home by travellers, appear to be far 
more abundant in tropical climates than in our country. The species 
seldom occur of a very large size, very few attaining or exceeding two 
inches in length, or three in the expansion of the wings. 
Messrs. Kirby and Spence seem to consider that, in respect to the 
mode of taking their food, the Hymenoptera can belong to neither of 
