216 VAPORER MOTH PARASITES. 



fortunate in other particulars. It is exposed to the attacks of 

 parasites. These are minute bee-like insects pertaining to the 

 Family Chalcididje |n the Order Hymenoptera. They puncture, 

 the skin of these pretty caterpillars dropping an egg therein, 

 from which hatches a minute maggot which feeds internally upon 

 the fatty matter of the caterpillar, thus exhausting and eventu- 

 ally killing it. I once gathered two of these caterpillars which 

 I placed with some leaves in a box- Two days afterwards one 

 of them was found to be dead, and the other being lively and 

 vigorous was removed to another box. Next day, what appeared 

 to be the ends of little worms were seen protruding from the 

 body of the dead caterpillar. Upon the following day these 

 worms were found to be seventeen in number. They had all 

 left the dead carcase of the caterpillar and just above it upon 

 the side of the box they had arranged themselves in a circular 

 row, and had changed to pupse of a milk white color, 0.12 long 

 and half as broad, hanging by their tails with their heads down- 

 ward and their backs against the side of the box. This was upon 

 the last day of July. Next day they had changed to a pale red 

 color and had somewhat shrivelled, each having discharged a 

 little cluster of clay-yellow graias which were adhering to the 

 side of the box at the tip of their bodies. They subsequently 

 altered to a black color, and on the sixth of August they hatched 

 the winged insects, which were of a brilliant brassy green color, 

 with a blackish purple abdomen and white legs, and about the 

 same size as the pupse. In an account of the vaporer moth 

 which I published in the Country Gentleman in reply to enqui- 

 ries respecting it from some of the subscribers of that paper, I 

 named this insect (vol. vii,p.235) the vaporer-moth parasite (Tri- 

 chogramma 1 Orgyia) . 



This parasite measures 0.12 to the tip of its abdomen, the wings being 

 slightly longer. The head is brassy green, as broad as the thorax, three or 

 four times as wide as long, and appearing slightly notched in front when 

 viewed from above. The antennae are brown, the basal joints pale yellow. 

 They are composed of six very distinct joints, of which the first is long and 

 forms an elbow with the following ones. The second joint is smallest; 

 the fourth and fifth are equal, oval, and shorter and thicker than the 

 third; the last is boader than the preceding and longer than the third, and is 

 shaped like an elongated egg. The thorax is brassy-green and finely sha- 

 greened, twice as long as wide, broadest across the middle, the collar of a 

 crescent shape and separated by a very distinct suture, the scutel large, pro- 



