ON SALT WATER INSECTS. 49 



The imago (Fig. 5 ; a, wing) is coppery green, legs 

 testaceous ; femora with a greenish tinge above ; tarsi fus- 

 cous. On the vertex is a broad, shining bluish-green 

 area, very free from hairs ; a similar bluish-green spot 

 just in front of the antennae. Front very full, rounded 

 convex, pale green, with a pale, almost yellowish tinge, 

 concolorous with the under side of the head, except 

 beneath the eyes and behind the mouth, where it is 

 darker green ; a few long hairs on the vertex. Thorax 

 and abdomen green, with scattered black hairs. The 

 antennae blackish-green, three-jointed, the third being 

 minute and sunken in the head; the second joint large 

 and spherical. Length .15 of an inch. 



As this subject is so interesting, and as I have been 

 unable to obtain any of the larvae, I condense Loew's 

 description of that of E. riparia (H. salinaria) in order 

 that they may be recognized, and their habits farther 

 studied in this country. 



The larva is white, nearly six lines long, nearly cylin- 

 drical, pointed anteriorly, and acutely pointed behind, 

 with two long extensible respiratory filaments on the 

 terminal segment of the body. Beneath, are seven pairs 

 of short, somewhat wrinkled fleshy tubercles, beset with 

 black bristles. The three anterior segments of the body 

 are formed into a cone, the anterior very small, with the 

 mouth-opening a little turned up, with a pair of small 

 curved mandibles partly concealed, with one-jointed rudi- 

 mentary palpi, and two-jointed antennge. On the second 

 body-segment (prothoracic ?) are the anterior stigmata 

 which project out like a short, cylindrical spigot. The 

 body is covered with very minute hairs. It lives in the 

 bottom of the pools of brine, and creeps out of the water 

 to transform, when the body shortens, the two last seg- 

 ments becoming united into a conical tube, while the 

 respiratory tubes themselves remain unchanged, but be- 

 come directed almost perpendicularly, and the under 

 side of the abdomen is more arched. The larvae were 

 infested by a Chalcid, perhaps identical with Pteromalus 

 scdinus, which seems to destroy many of the larvae. 



I have also collected the puparium of an Ephydra at 



COMMUNICATIONS ESSEX INSTITUTE, VOL. VI. 7 MAKCH, 1869. 



