52 INSECTS AFFECTING DOMESTIC ANIMALS. 
minute animal life, and that a sudden access of food would accelerate the final 
transformations. 
A possible third connection between the overflow and this increase may arise from 
the fact that the larve, when the water rises, leave their attachments, or that the 
débris upon which they are fastene 2 becomes itself started by the flood current, and 
that in consequence the Jarve from hundreds of smaller streams and tributaries are 
carried away by the rising water and impelled into the current of the large streams, 
by which they may be carried for many miles, spreading out at last in the overflowed 
region at just the time when they are ready for their final transformations. On this 
theory the larve from regions far distant become massed in the overflowed region 
and vastly augment the numbers which have naturally bred there. 
THE TURKEY GNAT. 
(Simulium meridionale Riley.) 
The early history of the turkey-gnat is so intimately connected with 
that of the preceding species, and the losses due to the two species 
have been so generally confused, that what has been already stated 
upon these topics covers about all that can be said. It is unnecessary, 
therefore, even if it were possible, to give separate account in detail. 
In the insect itself, however, and in many details of its life history 
and habits, there is so much difference that it becomes necessary to 
give some attention to them. 
LIFE HISTORY. 
While the area occupied by the adults corresponds in general with 
that of the S. pecuarum, the breeding places appear to be quite different. 
In this species the breeding grounds are limited to the 
smaller streams and branches, and the larve are found 
attached to submerged dead leaves. Often these leaves 
are held by sticks, rails, and other obstructions, which 
serve to fasten them in the mud and at the same time 
create currents which are favorable to the existence of 
the larvee. 
The larva has the peculiar shape and appearance of 
the Simuliide larve in general (see fig. 16 for the larva, 
the hair line giving natural length). The markings of 
the head and body are much more irregular than in 8. 
pecuarum. They usually possess one or two lateral 
spots on the enlarged hind part of the body; the head 
lacks the regular arrangement of spots and lines; the 
breathing organs are quite different, and three main 
Fie. 16.—Simulium trynks branch each six times and the branches enter 
meridionale: lar- ; 3 3 
va, side view the trunk from the sides. 
enlarged (from 
Ann. Rept. Dept. : a ‘ ; f 
Agr. 1886). they crowd together upon one leaf in numbers varying from ten to 
thirty, and, judging from their uniform size, they must be the off- 
spring of the same parent. As the current away from obstructions caused by twigs 
and leaves decreases in swiftness, so do the larve decrease in numbers, until only a 
few feet away but one or two can be found. 
These larve are evidently somewhat social in their habits, as | 
