The Boll-Weevil Problem. 3 
INSECT PARASITES. 
The second of the means provided by nature for the control of 
the weevil is a large number of insect enemies. Il orty-five species 
which prey upon the boll weevil are known. Of these, 23 are para- 
sites, which by means of their special organs place eggs on the imma- 
ture stages of the weevil within the square or boll. The young of 
the parasite develop by feeding upon the boll weevils, which they 
ultimately kill. Thus parasites instead of boll weevils emerge from 
the injured fruit. These enemies of the weevil have existed in this 
country for an indefinite time. Their natural habit has been to 
prey upon weevils more or less related to the boll weevil which have 
been present in this country for many years. They never feed upon 
vegetation. Since the boll weevil offered abundant and favorable 
opportunities for reproduction, while their original hosts were gen- 
erally not very numerous, they have naturally turned their attention 
to the boll weevil. The weevil mortality due to these parasites is 
exceedingly variable. In many cases no mortality from parasites is 
observed, while on the other hand fields showing from 50 to 7 
per cent of the weevils killed by parasites are by no means rare. 
5 
OTHER INSECT ENEMIES. 
The boll weevil is attacked by a number of insects which are not 
parasites in a strict sense but prey upon it as food. The most im- 
portant of these predatory enemies are ants. Twelve species are 
known to attack the weevil. They are the minute brown ants and 
the yellowish ants that occur frequently in cotton fields and are 
observed running over the plants or on the ground. Their work is 
not against the adult weevils, but against the immature stages in the 
squares. Some species devote their attention principally to the 
squares that’ have fallen to the ground, while others habitually seek 
the insects within the squares that remain hanging on the plants. 
The larva of the weevil, incased in a thin covering, offers food that 
the ants are not inclined to overlook. They gnaw through the thin 
shell inclosing the weevil larva, and the latter is soon destroyed. 
In some cases more than half of the immature stages in fields have 
been destroyed by ants alone. To find 25 per cent so destroyed is not 
a rare occurrence. 
OTHER FACTORS IN NATURAL CONTROL. 
Among minor factors in natural control may be mentioned the 
development of plant tissue known as proliferation, which some- 
times crushes the immature weevils; and determinate growth of the 
cotton (the tendency to cease squaring about the middle or latter 
