DIPTEROUS ENEMIES. 129 
INSECT PARASITES. 
As already noted, among the more effective natural enemies of the 
Cicada are the other insects which prey upon the eggs in the twigs, on 
the newly-hatched larvee, and also, but to a much less extent, on the 
adults. The more common and characteristic of the insect enemies of 
the different stages of the periodical Cicada are given below: 
DierrRous ENEMIES. 
Some four species of two-winged flies have been found to subsist as 
larvee on the eggs of the Cicada, but none of these has been reared 
to the adult stage and, therefore, their specific identification is impos- 
sible. 
One of these bears some resemblance to an asilid, or, perhaps, more 
remotely, to a bombylid larva, and was found by Mr. E. W. Allis at 
Adrian, Mich., feeding on the contents of 
the eggs of the Cicada, piercing the thin 
shells and extracting the juices. These 
larve are very minute, not much exceeding 
a millimeter in length. 
The most interesting of the dipterous egg 
parasites is a cecidomyiid, which was found 
in February, 1886, with eggs deposited in 
sumac the previous season. When ex- 
amined, all the eggs had hatched except in 
some instances where they had been sealed 
up by the rapid growth of the wood, so as to 
prevent the escape of the larve. One of the Wis cosnacaaie ra eae 
eggs thus inclosed was of an orange color, © of the periodical Cicada: Larva, 
in distinction from the normal yellowish- = ™¢h enlarged, with anatomical 
: q > details at side. (Original.) 
white, and from it, on March 2, an orange- 
colored cecidomyiid larva emerged. Other larve, apparently of the 
same species, were secured in May from eggs in alder twigs. From 
none of these, however, were adult flies obtained. The larve ranged 
in length from 1 to 1.5 millimeters. Their general characteristics 
are indicated in the accompanying illustration (fig. 52). 
The fly parasite of the adult C’cada seems to belong to the family 
Tachinide, which includes a number of species similarly attacking 
grasshoppers as well as many other insects. The larve of these flies, 
which have not been carried to the adult stage, sometimes to the 
number of half-dozen or more, will occur together in the body of a 
Cicada, which they have almost or quite completely eaten out. 
51117—No. 71—07——9 
