282 ENTOMOLOGICAL NEWS. [Nov. , '03 



men, and by the time it reaches the surface end of the larval 

 skin it has worked a hole in the top of the head-piece. The 

 motion in freeing itself is interesting. The insect is upright ; 

 the thorax is repeatedly bent gently forward and jerked back- 

 ward ; as soon as enough of an antenna is free, it uses the 

 joints and pulls the end out ; the same with the legs ; it then 

 mounts the projecting pupa-case, draws out the abdomen, 

 steps lightly down upon the resin, spreads its wings and flies 

 off. The proceeding is very business-like ; at each stage it 

 seems to know exactly what to do, and does it promptly. The 

 whole procedure occupies less than four minutes after the head 

 emerges. The projection of the pupa-case (Fig. 4) is inci- 

 dental to the efforts, as the escaping insects often walk over 

 the resin itself. 



The number of larvae that develop in any one lump is con- 

 trolled partly of course by the number of eggs deposited, but 

 more by the supply of resin. Eggs deposited in the spring 

 when the resin flows abundantly, have a better chance for life 

 than the succeeding generation, many of which perish by the 

 drying of the small drop, and by the attacks of parasites. 

 Throughout July a Proctotrupid parasite of the larvae was fre- 

 quently observed. This is one of the smallest of the para- 

 sitic hymenoptera, Polygnotus pinicola Ashm. described by 

 Ashmead as a parasite of Diplosis phii-inopis (Bull. U. S. 

 JNTat'l Museum, No. 45, p. 307), but now mentioned for the 

 first time, I believe, as a parasite upon Diplosis resinicola. Jul}' 

 was too late for me to find the larval stage, as they were 

 already pupating, as many as twenty in a single larval skin of 

 the fly. They feed upon the Diplosis larvae, consuming them 

 completely, leaving only the tough tracheal tubes untouched, 

 which together with the spiny outer skin serve to identify 

 these blackened skins as those of the Diplosis. The latter now 

 lie tangentially or slanting near the surface of the resin, the 

 irritated larvae being rendered no doubt too restless to remain 

 in position. The Polyg7iotus lie closely packed back to back, 

 generally with their heads toward the surface tip of the para- 

 sitized larvae. Before escaping they practise a few preliminary 

 exercises by popping the head out and back. 



