June, 1912.] 
Life-Histories of Syrphidae IV. 
535 
The skin is finely papillose when magnified. The character 
of the visceral matter often gives the larva a very granular appear- 
ance. The segments are marked by the usual twelve bristles in a 
transverse row. These are light in color, not elongate and not at 
all conspicuous; and are the only vestiture present. 
The character of the mouth-parts is more or less perfectly 
represented by Figure 67. Owing to the lack of favorable material 
I was unable to verify this drawing and it may not be perfectly 
accurate. The outer pair of mouth-hooks is present. 
The caudal branchial appendage is prominent, elongate, about 
0.5 mm. in length by 0.125 mm. in breadth; of two cylinders fused 
mesad except at the extreme tip where they diverge slightly( Figs. 
66, c; 68). The usual three elongate spiracles and circular plate 
are present on each half. The spiracular elevation is about three 
times as long as broad. There is a short, spur-like spiracular 
spine between each two spiracles, one between the most dorsal 
spiracle and the plate, and one mesad from the most ventral 
spiracle. These spines are continued down the sides of the tube 
as more or less evident ridges. 
Larvae of this species were found abundant on the leaves of 
flowers and fruit of the persimmon ( Diospyros virginiana L .) on the 
University Campus June 1 and 2*. They were feeding on the 
nymphs of an undetermined species of Aleyrodidce which caused a 
curling of the leaves. 
An autumn generation occurs commonly on cabbage and related 
plants where they are predaceous on A phis brassicce . Larvae were 
taken from this host-plant at the University Farm from September 
20 to October 10. 
Near Lakeville in Wayne Co., larvae were taken from curled 
dock, June 16-18; and at Sandusky, Ohio, from the same plant 
June 23. These were among colonies of A phis rumicus. 
The larvae are thus seen not to be closely restricted in their 
food habits, attacking at least two species of Aphididce and one of 
Aleyrodidce. 
These larvae live entirely on the surface of the plants where they 
are found and probably do not move farther than is necessary to 
secure their food. On the persimmon the larvae were found on the 
flowers, but chiefly on the leaves, especially under the rolled up 
edges, where the Aleyrodid nymphs were commonest. On Rumex 
they were to be found mostly in the spikelets and on the under side 
of the leaves where the plant lice occur. 
Whatever the host, the method of feeding is the same. The 
body-wall of the aphid is pierced by the mouth parts and the soft 
contents picked and sucked out while the head is pushed farther 
and farther inside the victim’s skin. 
*1 am indebted to my fellow-student, Mr. J. Lyonel King, for first 
calling my attention to these specimens. 
