72 
Psyche 
[Vol. 90 
Figs. 5-8: Case and larval morphology of E. canadensis. 5, Case of 3rd instar larva. 
6, 3rd instar larva, lateral view. 7, Tarsal claw. 8, 2nd abdominal spiracle. Arrow 
indicates juncture between original egg case and larval additions. Scale bars = 500 
(Figs. 5-6) or 10 (Figs. 7 8) yum. 
the frequency of encounter between predator and prey far above the 
usual conditions in nature. The coccinellid, H. glacialis, never suc- 
ceeded in capturing an encased larva and nine of the ten encased 
prey consumed by the pentatomid, P. maculiventris, were taken 
only after all of the exposed larvae in the dish had been eaten. The 
rate that exposed larvae were consumed by N. subcoleptrata and H. 
glacialis was increased by starvation (Fig. 1 1). 
The protective function of the larval case is further illustrated by 
its influence on predator behavior. The predator appeared to 
approach in response to prey movement with the outcome that 
attacks were launched, without apparent discrimination, on both 
exposed and encased larvae. Attacks on exposed larvae were 
quickly and invariably successful. Upon encountering an encased 
larva, the predators with sucking mouthparts {N. subcoleoptrata 
and P. maculiventris) touched the case with their forelegs and 
extended their beaks. They were never able to penetrate the case 
