THE BIoLoGY OF THE CHRYSOPIDAE 1333 
Manner of oviposition 
The stalked eggs of the Chrysopidae early attracted attention, and 
the manner of oviposition has been correctly described, at least in the 
main, by several writers, notably Fitch (1855), Mueller (1872-73 a), 
Vine (1895), and Girault (1907 a). 
Oviposition has been observed many times by the writer both under 
a hand lens and under a binocular. A female with a much swollen 
abdomen may be expected to oviposit soon. Furthermore, if a female 
is seen to have very recently deposited a few eggs, oviposition may gen- 
erally be observed without a long wait on the part of the observer. There 
is a constant twitching and contracting of the abdomen preceding ovi- 
position. Rings of contractions run posteriorly, and the abdomen is 
repeatedly raised and lowered. The female is usually quiet, moving 
only when disturbed. The vulva becomes more prominent, then it bulges 
out, and immediately before oviposition it is pushed out to its limit, 
being then very conspicuous. Finally the abdomen is brought to the 
substratum once or several times. Then it touches the substratum 
apparently with more force, and a drop of clear gelatinous substance is 
exuded. Following this exudation, the abdomen is raised stiffly upward. 
The gelatinous substance is pulled out in this way into a long, fairly 
uniform stalk. Immediately the egg appears, micropyle end last, and 
attaches itself to the stalk. The egg is held for an instant, presumably 
while the stalk hardens. 
It was observed that the egg in many instances was held not by the 
genitalia but by the small amount of stalk material which adhered to 
it. When the drop of gelatinous material appeared, the genitalia were 
immersed in it before it was drawn out. The egg adhered to it and 
was held for a few seconds. If the abdomen was lowered a trifle, the 
stalk bent out of line. After the stalk hardened, the adult freed itself 
from the egg with a little jerk. Some of the gelatinous substance was 
frequently seen on the eggs. 
The females of the less common species refused to oviposit in 
captivity, though several types of containers and foods were used. It 
should be pointed out further that some exotic chrysopids normally 
deposit unstalked eggs, but all of our species thus far studied normally 
deposit stalked eggs and all oviposit in the manner described. 
Abnormalities in oviposition.—Various peculiarities have previously 
been described as accidents of oviposition. In closely grouped eggs, as 
are frequently found with Chrysopa nigricornis, striking abnormalities 
may be observed. Most species deposit their eggs singly, but Sharp 
(1895) reports C. aspersa as laying its eggs in groups, each group being 
supported by a single stalk. 
