1312 Rocer C. SmirH 
As the larva feeds, the antennae are held almost erect and the 
labial palpi are held a little forward of straight downward. Undoubt- 
edly in these positions these organs are the least likely to come in con- 
tact with the struggling aphid; such contact would either afford some 
assistance to the aphid in its feeble efforts to get away, or impede the 
process of turning it over. 
The aphid is nearly always elevated more or less. This is undoubt- 
edly in order to lift the struggling aphid into the air and make its move- 
ments futile—not to allow the juices to run down the tubular mouth 
parts of the larva, as is sometimes stated. 
In very young larvae, one can see alternate pharyngeal contractions 
and expansions near the middle of the head during feeding. This can be 
observed in newly hatched larvae of Chrysopa quadripunctata. Fur- 
thermore, if these young larvae are given a small red aphid, a spurt of 
red juice may be seen flowing into the pharynx with each backward pull 
on the maxillae. The stream of juices flowing up the tubular mouth 
parts may be observed also in grown larvae. At the beginning of the 
feeding, there is generally an uninterrupted stream up each mandible; 
but as the aphid nears exhaustion, the streams are broken by air bubbles 
so that their rate of travel up the tubes may be readily observed. When 
the maxillae are pulled back, these bubbles fly up the tubes very rap- 
idly. At the end of the feeding, only an occasional drop is obtained. 
No evidence of the injection of any fluids into the body of the aphid 
has been observed. The maxillary movement may serve in part to 
assist in breaking down internal tissues, as these tissues are completely 
disintegrated, leaving lttle more than the chitinous parts to be cast 
aside. 
On the ventral side of the head there is more movement visible 
than on the dorsal. The entire venter of the head, the labium, and the 
labial palpi, move back and forth with the maxillae. This movement is 
most evident in the region of the bases of the labial palpi. If only one 
mandible is inserted, the movement is confined to that side of the venter. 
The rapidity with which the larva can shift the sucking from one side 
to the other is striking. First it sucks with one jaw, then with the 
other, and then with both, more quickly than can be timed. 
The muscular action which enables the larva to suck up liquids can 
be understood by a study of cross sections (Plate LX XVII; also Lurie, 
1898). There is a prominent muscle extending from the floor of the max- 
illa to its upper wall, being attached just beneath the depression that 
forms the lower part of the sucking tube. This strong muscle is present 
in all sections from the bases of the maxillae to very near the tips. There 
is another prominent muscle from the tubular connection of the jaws to 
