@oolbope Naturalists’ Field Club. 
ON THE MOULTING OF ORGYIA ANTIQUA. 
By T. A, Cuapman, M.D., Burghill, Hereford. 
THE Orgyia Antiqua is one of our very commonest insects, and a small de- 
tail in its life history is the subject of the note which I propose to lay before 
you. Though the matter is thus apparently trivial, I hope that it may not be 
regarded as unworthy of the Woolhope Club, as I think it will throw a little 
further light on a subject that has not been much elucidated, and as no fact con- 
cerning life in any, even of its lowest forms, is devoid of interest, as helping us to 
a fuller understanding of its processes in those higher forms which more personally 
concern us. 
All insects undergo certain so-called transformations—in other words, they 
cast their skins at certain intervals, and make their growth by being thus provi- 
ded with a new and more expansible integument, and as each skin admits of no 
other change than expansion, a certain amount of the change from the embryonic 
to the perfect condition is effected, apparently and, to a certain extent, really, 
per saltum, at each change of skin. 
The first change is from the egg to the larva stage ; the larva changes its skin 
several times, the pupa state is then assumed, and then that of the perfect insect. 
The change, first from the egg to the larva, from that to the pupa, and then 
again to the imago, are all very distinct and definite in character ; but the changes 
occurring when the larva changes its skin and becomes a size larger are less 
striking, and it becomes of interest to determine how far they are and how far 
they are not, of as definite a character as the change to pupa or to imago. 
It is unquestionably the case that in very numerous species of insects, the 
larva changes its skin or moults a definite number of times, and the larva after 
each moult is quite distinct in some respect from its condition at other stages, and 
is, indeed, as definite and distinguishable after each moult as the pupa or imago is, 
In avery large number, perhaps the majority, of species in which the facts 
have been recorded, the definite number of moults is four. This is the case in 
many Bombyces, and Sphinges, and some Noctue. I have recorded in our Trans- 
actions that this is the case in the worker of the common wasp, and curiously 
enough, 1 have recorded in the same place the smallest number of moults that 
occurs in any larva that I know of, viz., two, in the case of Rhipiphorus Paradoxus. 
Five moults would appear to obtain in not a few Lepidoptera, and so many 
as ten and eleven have been observed in some species. 
