42 
Psyche 
[June 
Field-collected gravid females were put in separate fruit 
jars with cheese-cloth coverings, and eggs obtained from 
them were isolated in one-ounce bottles with absorbent 
cotton plugs. Larvae were given about a dozen field- 
collected aphids every day or every other day. Sometimes 
larvae were fed termite workers. They spun cocoons, 
pupated, and emerged in the small bottles. Adults lived 
and reproduced satisfactorily in fruit jars. They were 
given a few aphids and a little water daily. The average 
duration of the egg stage was approximately three days 
and the larval stage, 14 days. Adults usually emerged 14 
days after the cocoon was spun. 
Two varieties were reared, inbred and inter-bred, namely 
the common oculata, which has four spots on the vertex, and 
illepida, which has two elongate bands on the vertex. 
Seven oculata females of unknown ancestry, some from 
different localities in Maryland, produced 103 offspring. 
Of these, 101 or 98% were oculata. There were one illepida 
and one xanthocephala (a form with only two spots). The 
progeny of two wild illepida females consisted of 83 in- 
dividuals, 58 of which were oculata and 25 of which were 
illepida — respectively 70% and 30%. 
Twelve pairs of first generation individuals were mated 
so that offspring of nearly all possible combinations could 
be studied. To determine whether or not there was any 
sex linkage, duplicate crosses were made in which the 
sexes with given characters were reversed. 
Results of second generation pairings are given in Table 
1. It is obvious that the genes responsible for oculata are 
more prevalent. This appears to be true not only in the 
populations reared but also throughout the range of the 
species. It is unlikely, however, that oculata is a dominant 
character in the Mendelian sense, because of its occurrence 
in offspring from illepida parents. Pairing F as given in 
the table shows that one pair of illepida from an illepida 
female produced 50% oculata offspring, indicating that 
they carried the oculata gene. This high percentage fur- 
Explanation of Plate 4 
Markings on the vertex of Chrysopa oculata. A. Variety oculata. 
B. Variety illepida.. C. “Borderline 0 individual. 
