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Psyche 
[June 
of eggs for Abedus could be substantially accelerated by increasing 
the temperature of the incubation water. Open water temperature 
in my laboratory (18 C) fell within the range of spring, fall and 
winter stream temperatures in Arizona. 
HATCHING 
Twenty-four hours prior to hatching, the free end of the egg 
swells dorsally. Pressure from within eventually causes a rupture in 
the chorion around the cephalic cap (Fig. iB). Invariably, nymphs 
hatch facing the brooding male’s posterior. I can’t explain this con- 
stant orientation of hatching nymphs, but its effect is that adjacent 
eggs can hatch simultaneously with a minimum of interaction be- 
tween eclosing nymphs. The cap is lifted by the head as the nymphal 
thorax emerges, but remains hinged to the egg on the side of the 
latter which faces the ventral surface of the emerging nymph. The 
nymph’s head slips from under the operculum as peristaltic contrac- 
tions free one half of the body. When the nymph is two thirds re- 
moved, it rests in a position perpendicular to the plane of the egg 
plate (Fig. iC). Moments later it arches backward and stretches its 
legs which are employed in final extraction when the nymph again 
leans forward. A newly emerged bug generally lingers on the back 
of the male for several minutes to inflate its laterally constricted 
abdomen (Fig. iD). This accomplished, it moves off in search of 
cover among aquatic plants or debris where it assumes the predatory 
stance characteristic of nymphs and adults alike. Freshly emerged 
nymphs are light honey yellow in color and translucent, but darken 
within one hour. 
Nymphal Development and Nymphs 
DEVELOPMENT 
Of 31 nymphs reared in the laboratory, 26 survived to adulthood. 
Individual developmental records are illustrated in Fig. 2 and mean 
developmental periods are presented in Table 1. These results com- 
pare favorably with those of Voelker (1968) for Limnogeton and 
probably reflect critical minimum periods required for morphogenesis 
between molts under optimal conditions. That availability of food 
is an important factor related to intermolt time for these sedentary 
hunters was demonstrated in a simple experiment. Ten of 20 sibling 
first instars, fed Drosophila daily, all molted in under eight days 
while the other ten, fed every fourth day, did not begin to molt until 
the nineteenth day. Thirty additional sibling first instars were di- 
