75 
the adults June 30. My own experience with the parasite leads me to 
take no exception to the accounts already published by Riley (Insect 
Life, Vol. I., pp. 101-104, 338, 339) and by Weed and Hart {Psyche, 
Vol. v., pp. 188-190). Briefly, it may be said the beetle is found 
standing on a leaf and looking quite natural ; indeed, it can still move 
some part of itself in most instances, tho it can not move away from 
the spot, for it is held by its feet to a brown mass of silk — a cocoon, 
from which the parasite will emerge in its winged form. The beetle 
may remain alive in this condition for two weeks and doubtless a 
little longer, but when disentangled from its foothold it is unable to 
move its legs in coordination — is unable to walk. 
The larva that made the cocoon has issued from the beetle and 
could previously have been found inside the host, but some mystery 
exists as to where the larva makes its exit, for the shell of the beetle 
appears to be unbroken. 
This Perilitus, then, is a check upon the beneficial ladybird beetle, 
but is of no practical importance on account of its infrequency. 
On many occasions I have seen adults of Podisus macnliventris 
(spinosiis) and Enschistus variolarius sucking the pupas of various of 
the coccinellids that prey upon the clover-louse. The eggs of both 
these pentatomids are heavily parasitized by a proctotrypid. 
Syrphidce. — Among the commonest insects of the clover field are 
several species of Syrphidce, or flower-flies (Fig. 7, 8), some of which 
are known also as "sweat bees." Many of these flies are banded with 
black and yellow, and have the habit of poising over this or that spot 
for a few moments and making short dashes from one place to another. 
The flies lay their eggs in or near colonies of plant-lice, upon which 
the larvae are to feed. The larvae are leechlike in form, and generally 
green, yellow, or mottled brownish in color. They are often seen 
among the aphids, which they destroy at a rapid rate. The syrphid 
larva seizes an aphid between its hooklike jaws, holds it aloft and 
sucks the blood from the body, meanwhile waving itself to and fro. 
When full grown, the larva shortens and its skin hardens into a brown 
pear-shaped or elongate puparium, from which the fly will issue. 
In this region the flies are seldom noticed in the clover field be- 
fore the latter part of April, but are abundant by the last of May. 
The larvae grow rapidly, and there are several generations of the com- 
mon species each year. 
In Maryland, Johnson found the syrphid larvae to be the most im- 
portant of the insect enemies of M. pisi, which they nearly extermi- 
nated in some localities. One pea grower sieved out twenty-five bush- 
els of syrphid larvae in a few days. 
Allograpta obliqua Say, he found to be by far the most common 
and most important species, forming the greater bulk of the twenty- 
five bushels mentioned. He refers to the larvae as being pea-green, 
slightly streaked with white, and one quarter to one third of an inch 
in length when full grown. The puparium is usually found on a leaf 
or stem, rarely on the ground. 
