1974] 
Smith — Life History of Abedus herberti 
279 
30 - 
25 - 
10 20 30 40 50 60 
MEAN MOLT TIME (days) 
Figure 3. First through fifth instar nymphs of A. herberti. Mean length 
and mean duration of instars illustrated graphically. 
vided into three groups of ten individuals. Each group was kept at a 
different temperature (18 C, 22 C, and 31 C) and all nymphs re- 
ceived Drosophila daily in numbers exceeding that which they could 
consume. All molted at approximately the same time (on the sixth 
or seventh day), suggesting that temperature is relatively unimpor- 
tant. These experiments were not intended to be conclusive and it 
is probable that a food-temperature interaction could be detected 
with more sophisticated experimentation. 
NYMPHS 
There are five nymphal instars for A. herberti. Dorsal views of 
the five are figured (Fig. 3) and mean morphometric data for fifteen 
characters of each instar are presented in Table 2. The wide (.001) 
confidence limits around each mean should encompass interpopulation 
variation for central Arizona. Mean size of bugs seems to be stream 
specific, perhaps due to low dispersal of these animals and reduced 
gene flow between their populations. A. h. herberti intergrades with 
