THE CANADIAN ENTOMOLOGIST. 



70 



rises above the water, she exudes from the genital opening a drop of a 

 gummy gelatinous substance, which she then presses against the object 

 that has been chosen to support the egg. This sticky mass is the base of 

 the egg-stalk, and hardening very soon, fastens the egg in place before it 

 has left the body. The insect now walks away from the stalk, thus free- 

 ing herself from the egg. This egg, as may be seen from 

 the drawing (Fig. 8), is long and spindle-shaped, with the 

 micropile on the extreme end away from the point of at- 

 tachment. 'I'he length of the egg is about two millimetres, 

 a little more than one-fifth the total length of the insect 

 apart from the antenna?, and about one-half the length of 

 the abdomen. I was unable to determine how many eggs 

 each female lays, for Hydrometra is not an easy insect to 

 raise in confinement, being easily drowned in aquaria, and 

 then the eggs are very hard to find where there is anything 

 J like an approach to natural conditions. The number can- 

 not be very great, however, for the size of the egg is such 

 that the abdomen could hardly contain more than four or 

 five at the most. Each egg is attached to its support at 

 right angles to the surface, but is frequently found hanging 

 down as the result of some accident. 



The interior egg sac is protected by a horny exterior 

 coating decorated with longitudinal ribs or flutings, the sur- 

 faces of which are granulated and marked by a rather in- 

 distinct hexagonal pattern; in the drawing this pattern has 

 been exaggerated in order to call attention to its existence, 

 for it is not at first apparent, and indeed does not appear 

 to be present in some cases. Around the micropile end 

 this protective coating takes the form of a series of plates, 

 while around the stalk it extends in an enclosing sheath of 

 a delicate tracery of network, through which can be seen 

 the darker coloured supporting stalk. Mounted in Canada 

 balsam this covering becomes more or less transparent, 

 showing the oval pod-shape of the egg proper, with its 

 slender stalk on one end and the micropile on the other. 

 Out of this egg there emerges, seventeen days after iay- 



mM^- 



m 



Fir. 8. — Egg of 



Hydrometra, [^^^^ t]-ie soft-bodied, light grecu nymph which has, as do all 

 Hemiptera, the general characters of the adult. The nymph in this case 



