6 BULLETIN 1040, U. S. DEPARTMENT OF AGRICULTURE. 
SEASONAL HISTORY. 
A most important feature in the biology of this insect was deter- 
mined by observing the habits of the insect during the spring migra- 
tion. The females, which during the winter have developed almost 
to maturity on the twigs, foliage, and fruit, migrate, in the spring. 
doAvn the limbs to the trunk to oviposit. This migration usually 
begins during the early part of April and continues throughout the 
month of May. It is estimated that over 90 per cent of the insects 
take part in this movement, although not all have reached full de- 
velopment at this time. They settle on the rough places in the bark 
of the main limbs and trunk and soon begin ovipositing. On severely 
infested trees these accumulations of females with their cottony egg 
masses appear as large bunches of cotton hanging from the limbs 
and massed about the trunk and may be collected by handfuls. 
(Fig. 4.) These egg masses begin to hatch the latter part of May or 
early part of June, and the young larvae start a migration back up 
the main limbs to the foliage and green fruit. The young settle 
along the midribs of young foliage, on the tenderest twigs, and under 
the sepals of the green fruit. Here they start feeding and their de- 
velopment is comparatively slow. By late fall many have become 
half grown and have settled in the more secure positions on the 
bud end or navel end of the fruit or between the fruit in clusters, and 
their development from then on is very irregular. During the 
winter many may have reached the oviposition stage, but the major- 
ity of the insects are still immature. There is a great reduction of 
numbers throughout the late fall and winter ; in fact, on many trees 
it is often difficult to find them, but with the opening of spring the 
matured forms again enter into the migration. There is only one 
main generation a year, although the retarded development of some 
insects and the hastened development of others cause an overlapping 
of generations and consequently the presence of some insects in 
various stages of development at different times of the year. There 
is a possibility of an offhatch or overlapping of generations in the 
appearance of egg masses during the winter. This occurrence, how- 
ever, is of minor importance in that the numbers of the mealybug are 
at their lowest at this time and most of the damage to the host has 
already occurred. 
The young larvae hatching from the egg masses in June are often 
killed by hot weather. In the summer of 1917 a very large percent- 
age of the larvae and eggs were destroyed by a short period of hot 
weather when the temperature exceeded 110° F. Again in the sum- 
mer of 1918 the hatching occurred just before a warm spell and many 
larvae were killed. That weather conditions and natural enemies 
are powerful factors in the control of this mealybug is very evident. 
