THE LESSEE COEN STALK-BORER. 15 
PROCESS OF HATCHING. 
Shortly before the larva is ready to emerge it can be seen very 
distinctly through the semitransparent shell. The brown-black 
head and the pinkish markings on the segments especially are con- 
spicuous. The larva occupies a curled position inside of the shell, 
with its head resting on the ultimate and penultimate segments of 
the body. Just preceding emergence a wavelike rhythmic motion 
is seen, starting at the head and continuing from segment to segment 
slowly to the end of the body, after which the larva moves its head 
about and with its mandibles makes an incision large enough for it 
to pass through. This takes about five minutes. The larva then 
usually rests a few minutes, after which it begins to draw itself out 
of the shell. 
NUMBER AND LENGTH OF INSTARS AND LENGTH OF LARVAL LIFE. 
The number of instars and their length, as well as the total length 
of the larval life, are extremely variable, as will be noted by referring 
to Tables IV, V, and VI. These variations are due in part to differences 
of temperature. During the summer months the larvae may molt 
four or five times and in fall five or six, making from five to six instars 
for the former and six to seven for the latter. The seventh instar in 
such instance resembles the sixth in color pattern and size. The 
second instar and sometimes the third is somewhat longer than 
the first during the summer months. In fall, however, the first instar 
is longer than any of the others, except the last one, or the one just 
preceding pupation, which is generally also the longest during the 
summer months. 
The length of the life of the larva is somewhat dependent upon the 
number of instars. The larger the number of instars the larva under- 
goes, the longer the period it will take in reaching maturity, as is 
brought out by comparing the averages of the instars in Tables 
IV, V, and VI. In Table IV the larvae having five instars reached 
maturity in 374.5 hours, while those having six instars reached 
maturity in 406.33 hours. In Table V those having five instars 
reached maturity in 397 hours, as compared to 453 hours for the 
six-instar larvae. In Table VI the six-instar larvae required 842 hours 
while the seven-instar larvae required 906 hours to reach maturity. 
The larvae may reach maturity in the short period of 13.8 days, but 
generally in about 16.8+ days, during the summer months. How- 
ever, one larva required as many as 20.8 + days to reach maturity. 
In fall, when temperatures are low, this period is considerably 
lengthened, varying from a minimum of 22.0+ to a maximum of 41.6 
days. 
