PLASTRAL RESPIRATORY DEVICES IN ADULT 
CRYPHOCRICOS ( NAUCORIDAE : HETEROPTERA) * 
By Margaret C. Parsons and Rosemary J. Hewson 
Department of Zoology 
University of Toronto 
Toronto, Ontario M5S 1A1 
Introduction 
Adult Cryphocricos live in very rapid, well-aerated streams, under 
stones and gravel at depths of from 6 to 24 inches (Fritz Plaumann, 
personal communication ; John Polhemus, personal communication ; 
Randall Schuh, personal communication). Under these conditions it 
would be difficult for these insects to come to the water surface for 
atmospheric air, as do “slow-water” Naucoridae and most other 
aquatic Heteroptera, and neither Polhemus (personal communication) 
nor Schuh (personal communication) have observed them to do so. 
Even if it were possible for Cryphocricos to obtain atmospheric air, 
the insects lack a means of storing large amounts of it for underwater 
respiration. Aquatic Heteroptera with “air-bubble” respiration carry 
much atmospheric air under their long forewings and trapped by long 
hairs on the ventral surfaces of their bodies. Long-winged Crypho- 
cricos, however, are very rare. Most individuals lack hindwings and 
have forewings which reach only to the third abdominal segment. 
The reduced subalar space on the pterothorax is too small to hold 
any appreciable amount of air (Parsons 1974). Thorpe (1950) 
concluded, from examination of a dried specimen of Cryphocricos 
sp., that it is “a bubble-carrier rather than a true plastron insect” 
and has “a substantial air film”. Polhemus, however, examined C. 
hungerfordi in the field and observed no such air layer except on the 
six pairs of small ventral abdominal sense organs (Polhemus, per- 
sonal communication). Parsons (1974) observed a very thin air 
layer on the ventral surfaces of the thorax and abdomen in formalin- 
preserved C. barozzii, but this layer is visible only under the stereo- 
scopic microscope and is usually hidden by the debris which covers 
the insect. 
Young’s (1944) suggestion that Cheirochela (Naucoridae) sur- 
vives by cutaneous respiration appears highly dubious, and it is un- 
likely that Cryphocricos uses this method to any great extent. The 
*Manuscript received by the editor February 6, 1975 
510 
