57 
mologists. arrived at the conclusion that there was one generation of 
the insect in the transition zone, two in the upper austral, and three in 
the lower austral. B}^ using the conclusions of recent years the writei 
finds that there is one generation in the tran>ition zone, with often a 
partial second, two generations in the upper austral, and two in the 
lower austral, with a possibility of a partial third. 
NATURAL CONDITIONS WHICH TEND TO DECREASE NUMBERS. 
It has often been noted that a >udden fall of temperature is fatal to 
a laro*e number of the smaller larva* of the codlincr moth. It has 
been already noted that Professor Aldrich has recorded such an obser- 
vation. Hot sunshine and extreme dryness cause many of the pupie 
in the case to die. A moist climate aids fungi and bacteria to such an 
extent that sometimes most of the larva? are killed by them. Larva^ 
that are killed by fungous diseases are hard and mummified, and 
have a whitish appearance. Bacteria cause the internal organs to dis- 
integrate and the larva to become limp and full of juices of a brown 
color. 
NATURAL ENEMIES. 
Although the codling moth has many natural enemies, the number 
as compared with those of other Lepidopterous larvae is comparatively 
small. This may be accounted for ])v the fact that the insect through- 
out the greater ])art of its life is more or less protected, but when the 
larvte have left the fruits and are seeking places in which to spin their 
cocoons and when in the winged stage they are attacked by numer- 
ous enemies. Birds are ])y far the most efficient natural enemies of 
this insect. Anyone who tries to collect the larvjv from the trunks of 
trees in spring will find very few specimens, but, on the other hand, 
will Hnd many empty cocoons. The writer has many times in the 
spring searched persistently for larvie in the rough bark and the more 
exposed cracks, but found practically none, although many could be 
secured by cutting into the holes and cracks of the tree. Kiley, 
Walsh, and Slingerland also note this effectiveness, and the amount of 
good the birds do can only be estimated. The cocoons are always 
found, and on a close inspection of the bark a telltale hole discloses the 
story of some woodpecker's work. It has often been noted also that 
the same birds have made holes or enlarged the cracks in tlu^ stubs of 
old branches for tlu^ purpose of digging out the lar\"a\ IMate \'III. 
figs. 1. -2, 3, shows stubs of branches from an old orchard mwv Klkton, 
]\ld., in which these birds have done t^tliciiMit work in reducing the 
number of larva> during the spring. Fig. '2 is especially interesting, 
as on close examination it shows the following points: Some time in 
1900, in the course of pruning the orchard a branch was cut away, 
leaving the stub, which is s incluvs long. In the foUov^ino- winter and 
