PACKARD] THE EMBRYO LOCUST. 633 



amnion, I was able to plainly see in a specimen, which the moment after 

 the auiuiou was forced back from the head opened the jaws and thrust 

 out the palpi and antennoe. The amnion is sometimes nearly shed be- 

 fore the embryo has entirely extricated itself from the egg-siiell. The 

 outer embryonal layer, or " serous membrane" of Kowalevsky, may be de- 

 tected by rubbing off the chorion. 



I have found six stages in the life-history of the Rocky Mountain 

 locust, with consequently five molts, with the following characters as 

 seen in the female sex of each stage : 



1. First larval. Head very large, and abdomen short and small ; 

 antenna? 12-jointed. Length, 14-15"'". 



2. Second larval. Head smaller; antenna? IG jointed; lower edges 

 of tergum of mesothoracic ring and especially meta-tlioracic full and 

 rounded, ^o diflerence from the first stage seen in a dorsal view ; colors 

 deeper, markings more distinct. Length, 7-8J™™. 



3. Third larval. Head about the same size proportionally as in the 

 second stage ; lower sides of meso- and meta-thoracic rings subacutely 

 produced, evidently the rudiments of the wing-pods of the pupa. The 

 proportion of the prothorax to the two posterior segments is the same 

 as before. Length, 9-11™"". 



4. First pupal. Antennae 20-jointed ; prothorax much produced back- 

 ward, wing-pods well developed, covering the tergum of the meso- and 

 meta-thoracic segments, so far as they are not concealed by the over- 

 lapping of the prothorax; outer pair twice as large as the inner jDair; 

 the hinder pair 2^"™ in length, or two-thirds as long as the prothorax. 

 Length, 15™'". 



5. Second pupal. Antennte 22-jointed ; prothorax still larger; hind 

 wing-pods as long as the prothorax. Length 20'"'" (1 inch). 



6. Imago, or adult, with wings fully developed. Antennoe 23-24- 

 jointed ; eyes more rounded than in the pupa ; hind femora slenderer. 

 Length of body, 25'"'". 



It will thus be seen that there are three larval and two pupal stages 

 besides the adult stage. 



The embryo locust, — On removing the living embryo from the egg-shell 

 under (Plate LXII, Fig. 2), it is found that it lies with the legs folded on 

 the side of the body, the fore and middle pair folded directly across the 

 thorax, while the hind pair are laid along each side of the abdomen. 

 The antenna? lie on the face each side of the clypeus and labrum, or 

 upper lip. The eyes are dark reddish, and the head, limbs, and cross- 

 lines on the back of the body are reddish mixed with yellow. Beneath, 

 the body and legs are white. By putting the eggs in alcohol the shell 

 becomes more transparent, so that the head, eyes, limbs, and reddish 

 portions of the body become visible. Length of embryo at time of 

 hatching 0.21 inch. Described from living specimens received from i\Ir 

 S. D. Payne, Kasota, Lesueur County, Minnesota, March 1, 1877.* 

 Either during the night of the 13th or early in the morning of the 14th 

 of March nearly all the larva? (the eggs having been kept in a warm 

 room) hatched at the same time. The egg-shell bursts open at the head- 

 end, when the larva immediately after extricating itself from the egg 

 casts oif a thin pellicle (the amnion or faJtenhlatt), as I have seen in 

 the larviB of the flea, currant saw-fly, and other insects. Before the 

 skin is cast it is almost motionless, and by slight movements of the 

 body in about five minutes draws itself out of the amnion. The pro- 



* This shows that tbe embryo locust develops iu the autuuiu iimiiediately after the 

 eggs are laid, and that it lies dormaut (a few occasioually hatching in the autumn) 

 during the winter, ready to burst its egg-shell iu the spring. 



