Vol. XXviii] ENTOMOLOGICAL NEWS 2OJ 



Nearly immediately on emerging the nymph casts a diaphan- 

 ous pellicle, very soft and hairy, so soft that it does not retain 

 its shape at all and is nearly invisible on the surface of the 

 water. This pellicle, which I prefer to consider in the nature 

 of an amnion rather than as a true molt, shows the one-jointed 

 tarsi, subapical claws, tibial combs on all legs, but the other 

 details are much obscured. The covering hairs are long and 

 matted. As already noted the just-hatched nymphs sink and 

 have to break through the surface film before beginning active 

 life. 



Nymph, First Instar. The antennae are moderately stout, joint 2 

 shortest, 4 longest, as long as i and 3 together, next in length being I 

 and 3. The ommatidia are round. All the tarsi are i-jointed and all 

 the tibiae have combs. The first pair of legs is shortest and the 3d 

 longest; the tibia and femur are subequal in the first pair; in the sec- 

 ond the tibia is longer than the femur and in the third shorter. The 

 legs are set apparently very far back, due to the excessive shortness of 

 the abdomen arising from the very narrow, ringlike segments. The 

 head is rounded and hairy with a few scattering long setae. The ros- 

 trum is stout, with the third joint longest, then the 4th, followed by the 

 2d and ist in that order. The 4th is black and tapering. 



Second Instar. This instar is much the same as the first, except that 

 the legs are not apparently so far back on account of the lengthening 

 of the abdomen. It is also changed as follows : The first pair of legs 

 continues the shortest, but the second is the longest; the tibia of the 

 first pair is shorter than the femur and in the second pair they are sub- 

 equal, while in the third pair the tibia continues shorter. The second 

 joint of the antennae is the shortest; the first and third are subequal 

 and the fourth longest as before. In the cast skin in this and all in- 

 stars, the second joint appears cupped at the distal end and the third 

 joint is sunk into it nearly half way. In this instar in the cast skin, 

 from which these dimensions and proportions were taken, a long spir- 

 acle is seen on the propleurae, near the upper edge. 



The nymph in this and other instars was mounted in balsam, and in 

 this case too much shrunk for exact study. 



On emerging from the first molt, the nymph is very translucent and 

 rather colorless, excepting the eyes, which are red. 



Third Instar. In this the nymph is as in the first, except as follows : 

 The anterior femur and tibia are subequal, the proportional length of 

 the legs and proportional length of leg joints remaining as before. The 

 antennae are as before, except that the third joint is longer than the 

 second, the first longer than either, the fourth continuing the longest. 



