PROCEEDINGS OF THE SECOND ENTOMOLOGICAL MEETING 9 
from some Hill district in which the insect breeds during the period 
between April and August. 
If you come to Pusa during the first half of February in any year and 
look around the cabbage-plots you will see numbers of Pieris brassice 
flying around and ovipositing on the plants. If you had come here a 
fortnight earlier, in the second half of January, you might have looked 
for a long time without seeing a trace of this butterfly in any stage. 
At Pusa, generally on or about Ist Febr uary in every year, the butterflies 
suddenly appear in some numbers, and it is noticeable that most of them 
are worn examples and a large proportion is composed of females. These 
oviposit and two or three broods result until about the beginning of 
April, when the insect again disappears completely until the next year. 
We have been quite unsuccessful in carrying it on beyond this, and, so 
far as we know, this insect is not found at Pusa in any stage between 
May and January. Whence then do the first butterflies appear about 
Ist February ¢ Once again, from the facts of the case and from records 
of known migration-flights of Pieris brassice in Europe, we are driven 
to accept the theory—remember, it is only an unproved theory in 
this case also—of migration. 
Here we have the cases of two common insects, regarding whose 
hifehistories, in Bihar at all events, we must confess our ignorance in 
spite of various attempts to bridge the gaps in our knowledge. If we 
had exact records, with exact dates, of the appearance and disappearance 
of these two species in adjacent or other areas in India, I venture to 
think that such records might throw some light on the subject and would 
at least yield something in proof or disproof of our present theories of 
migration from other districts—theories which fit the facts so far as we 
know them at present but which, I repeat, are as yet mere suppositions. 
With further reference to such points, I am now going to read two 
short extracts from the Annual Reports of the Pusa Institute for the 
last two years, that is, since our last Meeting. In the Report for 1914-15, 
I wrote :— 
‘A point, which has been observed with regard to some common 
insects (Laspeyresia, Chilo, Chloridea) reared for observation 
of exact cycles of their lifehistory, is that out of the same 
batch of larvee, feeding and commencing to hibernate at the 
same time, some hibernate and emerge as adults”, that 
is to say, they hibernate and emerge as adults as soon as 
the weather begins to warm up after the cold season, ‘‘ whilst 
others hibernate during the cold weather, then aestivate 
during the hot, dry season and emerge at irregular intervals 
thereafter as late as July or August. From the practical 
