NOTES ON THE LIFE HISTORY AND ANATOMY OF 
SIPHONA PLUSLE Cog. 
By WILitAM BLOESER, Stanford University, Calif. 
LIFE HISTORY. 
The Tachinid fly, Stphona plusie, was described by Coquillet 
in 1897. It was bred from a cut-worm. The specimens that 
I have obtained, however, were parasitic in the larve of Phry- 
gamdia californica, gathered from oak trees at Stanford Uni- 
versity. 
The Phryganidians were more than plentiful during the 
fall of 1913, and consequently there was an abundance of par- 
asites. Sztphona is only one among a dozen or more parasites 
that are nursed in their infancy by the accommodating Phry- 
ganidian, but notwithstanding the ravages of all these parasites, 
and the scourge of a fungus disease, which killed nearly one 
third of the caterpillars, there were still many left, sufficient to 
insure a great number of moths again in the following spring. 
The following notes on Szphona plusie are the result of 
observations made in the fall of 1913: 
The Egg. The adult female fly lays one or more eggs on 
the outer body wall of the Phryganidian larva. The dipterous 
parasites are not as careful as the hymenopterous parasites, and 
they lay their eggs indiscriminately, often laying three or four 
eggs on one host. 
The Larve. After the eggs have hatched the young larve 
make their way into the body cavity of the Phryganidian, 
where they remain from ten days to two weeks, feeding on their 
host until fully grown, when they measure about five-sixteenths 
of an inch in length. They have eleven segments; well devel- 
oped mouth parts, in the form of great hooks; two large pos- 
terier spiracles and two smaller anterior ones. 
The larve are loosely attached or held in a sort of cicatrix, 
in the body of the host, by several rows of small hooks that 
encircle the tenth and eleventh segments. From this position 
the head and anterior portion of the body are free to swing in 
the body cavity. Some larve are found, however, moving 
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