194 THE CANADIAN ENTOMOLOGIST. 



abdominal segments still within it. The legs are still held in the shelly 



and pressed against the body. A \e\v last heaves set free first the 



anterior pair, then the other two, and the little bug falls forward. Assisted 



by its legs, it pulls out of the shell and remains quiescent a moment, then 



feebly swims away. 



First Instar. 



Shape : The general shape is much as in the adult. The head is 

 shorter and broader ; the distance between the eyes is greater, the eyes 

 themselves being small. The thorax is wider than long, the abdomen is 

 rounded at the tip and covered with pile beneath. The flattened sides 

 are broad, and the deeper abdominal middle is about as wide as one of 

 the sides. The tarsi are all one-jointed,^^ about half as long as their 

 respective tibiae, and armed with two claws each, those of the anterior 

 tarsi of unequal length, the inner claw being about one-third shorter than 

 the other. The femora are aU grooved for the reception of the tibiae, and 

 sparsely fringed at the edges. The exterior side of the femora is armed 

 with stout spines, which are also found in the tibia? of the second and 

 third pairs of legs. The antennae are short, club shaped, and one jointed, 

 about one and one-half times as broad at the base as at the apex, and 

 twice as long as the greatest diameter. 



Size : Long., 4 to 5 mm.; lat., abd. 2.4 mm. 



Colour : Generally somewhat translucent grayish or brown. 



Markings : The head has a darker median stripe, produced by the 

 lancets. There are five white spots on the connexival edges, and also 

 near the middle of the body on each side. The legs are more or less 

 banded. 



When just emerged the shape of the nymph is more or less narrow 

 and elongated, but in an hour or so it broadens out to the form previ- 

 ously noted. The colour is then a transparent yellowish, and, as in the 

 other Cryptocerata, their transparency in their earlier stages exhibits very 

 plainly the dorsal vessel in motion, as well as the oily globules of the 

 unabsorbed yolk. Shortly after emergence, the young nymph casts off 

 the amnion as a clear pellicle, almost like a diaphanous moulted skin. 



When very young, the nymph finds it hard to pierce the surface 

 film. In fact, for some time after hatching, they appear unable to break 



II. Dufour (Essai Monographiqiie sur les Belostomides) notes that all larvse 

 of Belostomids have uniarticulate tarsi. 



