1971] 
Sheldon & MacLeod — Chrysopidae 
109 
at several localities in 'Champaign County, Illinois during 1970 
(Table 1). 
An experiment examining the nutritive value of corn pollen 
utilized the offspring of 20 females collected at Urbana, Illinois on 
15 June 1970 and maintained as a mass culture in an environmental 
chamber at 25±i°C and at a photoperiod of LD — 16/8. The 
females had constant access to water and a food consisting of a 
1:1: 1 volumetric mixture of Food Wheast®, sucrose, and water 
(Hagen and Tassen, 1970; Ridgway et al. f 1970). A sufficient 
number of eggs for the experiment was collected from a single 
night’s oviposition and these were placed singly in cotton-stoppered, 
two-dram shell vials. The rearings were carried out at the tempera- 
ture and photoperiod experienced by the adults in the mass culture, 
as described previously (MacLeod, 1967), except that vials contain- 
ing the immature stages were kept in a desiccator over a saturated 
solution of KBr which maintained a relative humidity of 80%. 
Upon emerging, the young adults were immediately divided by sex, 
and 40 of each sex were randomly distributed among the four diet 
groups shown in Table 2. Each group, still maintained under the 
same temperature and photoperiodic regimen as before, was provided 
daily with fresh food. The hand-collected pollen was fed dry, while 
the sucrose was presented in the form of a highly concentrated solu- 
tion absorbed in a small cotton pledget. A cotton pledget saturated 
with water was also available in all four groups at all times. 
The efficiency of these diets was measured by an examination of 
the condition of the reproductive system five days after eclosion. In 
males it was noted whether sperm had shifted from the testis to the 
seminal vesicle. This is an important initial step in the ontogeny of 
full reproductive activity by the male (MacLeod, 1967,* Sheldon 
and MacLeod, in prep.). In the females the basal diameter of 
the largest ovariole in each ovary was measured, 4 the number of 
mature eggs (diam. — 0.41 mm) was noted, and the number of 
yolky oocytes was counted. These scores, indicating the degree of 
development of the female reproductive system, should be excellent 
indicators of the adequacy of the diet since the process of yolk deposi- 
tion is undoubtedly responsible for the largest nutritional require- 
4 The number of ovarioles per ovary in C. carnea is nearly always 12. 
We have occasionally encountered specimens with 11 ovarioles in one ovary 
and 12 in the other, but this is the greatest departure from the normal 12/12 
state which we have observed. When yolk synthesis is underway, all of 
the ovarioles of a female are similarly active and usually they all have a 
similar basal diameter. 
