THE SUGAR-CANE MOTH BORER. 35 
STJKVIVAL OF HIBERNATED LAKViE. 
Only a small proportion of the larvae which go into hibernation 
survive the winter and emerge as adults. They die from time to 
time during the winter and those which have been in the larva stage 
for a long time seem to have trouble in pupating and often die in 
the attempt. Then, too, the mortality is higher among the pupse 
from hibernated larvae than from others, and the adults that emerge 
are not so vigorous. 
Not more than 10 per cent of the larvae kept under insectary condi- 
tions emerged, and as those pupating in the field often have the addi- 
tional trouble of emerging through some depth of soil, it is evident 
that only a small percentage survives. On account of their rapid 
increase in numbers it requires only a few moths in the spring to 
produce a large number of borers during the summer and fall. 
LONGEVITY OF HIBERNATED J.ABYM. 
The usual larval period is greatly prolonged by cold weather or 
other adverse conditions, and the larvae can survive great hardships. 
It is not at all uncommon for them to live for a month or two with- 
out food, and Stubbs and Morgan (152) have kept them for 75 
days without food and had them pupate afterwards. Rosenfeld and 
Barber (137) kept a larva for 200 days without food and it pupated, 
while E. R. Barber records placing a larva in the photographic 
dark room on October 19, and finding it alive June 9, a period of 231 
days, during which it did not feed on the piece of sugar cane pro- 
vided. The larva stage of overwintering individuals is generally 
about 7 or 8 months, and during this time there are 10 or 12 molts, 
but in the authors' experiments some required 276 days and 14 molts 
to reach the pupa stage. 
NATURAL CONTROL. 
CLIMATIC CONTROL. 
EFFECT OF RAINFALL. 
Mr. George N. Wolcott, while entomologist of the Insular Experi- 
ment Station, Eio Piedras, Porto Kico, made a number of observa- 
tions which tend to prove that the moth borer is adversely affected 
by rainfall. The following is an abstract of Mr. Wolcott's conclu- 
sions : 
A large number of careful observations made in Porto Rico during the past 
grinding season, confirmed by the evidence from other countries, indicates that 
there is a constant relation between the amount of rainfall and the abundance 
of Diatraea. The table, which gives the percentage of infestation of cane 
by Diatraea in conjunction with the total annual rainfall in inches for 1914, 
