COLOUR IN SPECIES. BS 
species of vultures, hawks, gulls, and a few others, the 
adult plumage is not put on until after two, three, or 
even four years. Humming-birds, and nearly all their 
splendid coloured congeners, during the first year, are 
devoid of those richly coloured plumes which they ac- 
quire in the second. ‘These instances are sufficient to 
set the young ornithologist upon his guard ; and yet, in 
mature life, the colours of birds are their best and most 
obvious distinctions. Among insects, also, they afford 
considerable help, especially in the Lepidoptera ; where 
the ground tint and the pattern are almost invariable 
in the individuals of one species, although there may be 
some trifling variation in the latter. The ocellated 
spots, for instance, in our well known meadow but- 
terflies, forming the groups of Hipparchia and Polyom- 
metus, will frequently vary as to their size and number, 
although the pattern of the wings will be, in other re- 
spects, precisely the same. In this order, the colours 
of the sexes are rarely different ; although there are some 
remarkable exceptions to this rule among the exotic 
diurnal tribes. In the Hymenoptera, also, the same 
species of bee will appear very different upon first 
emerging from the pupa, and when his short career is 
drawing to a close: the delicately coloured hairs, with 
which his body was at first defended, will be partly 
worn off ; and the dark colour of the abdomen, appearing 
beneath, will give the whole insect a different aspect to 
that which it had in youth. Let the young entomologist, 
if he wish to ascertain this fact, capture some of those 
species he will find on the wing at the end of July, 
and then renew his captures, in the same locality, in 
the month of September ; in all probability he will meet 
with the same species, but apparently clothed in dif- 
ferent hues. Colours, in the neuropterous order, are 
very evanescent. Those which ornament the bodies of 
the dragon flies, not only fade after death, but vary in 
individuals of the same sex: the beautiful green, so 
prevalent among the locusts, generally changes, in the 
preserved specimen, to a light brown: the under wings, 
T 4 
