THE BIoLoGy OF THE CHRYSOPIDAE Ue Ri; 
CC. Abdomen of the usual type, longer than head and thorax, tapering 
gradually and regularly posteriorly. Larvae never with well-de- 
fined packet of debris, but occasionally with some cottony materials 
adhering to dorsal setae. 
D. Head marks in two pairs, curving outward anteriorly; inner 
pair V-shaped but not confluent at base; outer pair extending 
from base of antennae in a sharp inward curve to prothorax; 
body gray, but marked with brown spots..........2.......----------s-0-------= 
Ty Sei be 5 i ae A wl ee ee Oe a Oa Se C. quadripunctata Burm. 
DD. Head marks in two pairs but extending straight forward, the 
two pairs parallel to each other; outer spots twice as large 
and broad as inner ones; body mainly gray, with prominent 
black saddle-shaped area on thorax_......... Chrysopa sp. 
The prepupa 
After a third-instar larva has reached maturity, it usually seeks a 
more or less protected place and spins a cocoon of white silk in which it 
transforms to a pupa. One cannot always tell by the appearance of a 
larva whether or not it will spin soon. Usually just before spinning, 
the larva engorges itself by devouring a larger number of aphids than 
usual and then becomes sluggish. It grows rather broad and usually 
appears to be somewhat flattened (Plates LXXXII and LXXXVI). 
The term prepupa is used to designate that part of the life stages begin- 
‘ning with the first spinning of silk and lasting until the molt to the 
pupa. 
Location of the cocoon 
In the open, the larvae spin on the under side of leaves, at the over- 
turned margins or tips of leaves (Plate LX XXVIII, 4), under rough- 
ened bark, in flower clusters, or under loose earth. In vials they usually 
spin under leaves, twigs, or a mass of aphid skins, near the cotton plug, 
or on the bottom of the vial. Observations indicate that the greater 
number go to the bottom of the vial to spin. 
It was found that larvae of Chrysopa oculata may spin their 
cocoons just beneath the surface of the earth in pot cages. In nature, 
cocoons of this species are not commonly found on plants. It is thought 
that they may go below the surface of loose soil and spin, which would 
account for their scarcity. The earth and sand adhere to the cocoon and 
make them quite inconspicuous. Cameron (1913) found that C. vul- 
garis also often pupates below the surface of the ground. 
Spinning the cocoon 
The early part of the spinning can be readily observed, but the 
latter part is difficult to see since the cocoon is only slightly trans- 
