198 REPORT UPON COTTON INSECTS. 



without stigma, the veins forming with the costa two closed cells ; hind wings with 

 a costal vein reaching and broadening to near the middle of wing, where it is sud- 

 denly bent upward. Abdomen narrower than thorax, with a short peduncle. 



D. zig-zag, n. sp. Average length, 1.6 mm . Body uniformly polished black. Legs, 

 palpi, and antennae reddish in female, the coxae, femora, and antennae toward tip infus- 

 cate in the male. Peduncled joints of antennae with a whorl of minute spines around 

 the crown, and longitudinally striate. Base of thorax and of abdomen with pale 

 pubescent hairs. Wings hyaline, sparsely beset with minute spines, which increase 

 radially and form a fringe around the posterior half ; the veins of front wings forming 

 a sprawling W, with partial cross-veins proceeding from the lower angles, the basal 

 cross-vein longest. 



The next three parasites which we shall mention belong to the family 

 Ichneumonidae, or ichneumon flies, as they are commonly and familiarly 

 called. These insects are characterized by unusually long and slender 

 bodies, and the long projecting ovipositors of the females. These ovi- 

 positors are often very long, and are protected by a sheath of four stylets 

 ef the same length as the true ovipositor. The head is usually rather 

 square, with long many-jointed antennae. The larva is a soft, cylindri- 

 cal, fleshy, white, footless grub, the rings of the body being convex and 

 the head small. The eggs are laid by the parent either on the outside 

 or within the caterpillar or other larva upon which its young is destined 

 to feed. When hatched, the larva devours the fatty portions of its 

 victim, just as we have seen with foregoing parasites, until it gradually 

 dies. The larva spins a cocoon about itself when about to enter the 

 pupa state. In the larger species this cocoon consists of a dense inner 

 case, and a loose, thin outer covering. Of the larger species but one 

 individual occupies the body of the host, while in the smaller species 

 many are found within one insect. The cocoons of most species are 

 spun within the body of the parasitized insect ; but others, as in the 

 genus Microgaster, emerge and spin their small, oval, often bright-colored 

 cocoons on the outside. The family, as a whole, is one the members of 

 which are of immense service to agriculturalists in destroying great 

 numbers of noxious insects. 



THE YELLOW-BANDED ICHNEUMON (Pimpla conquisttor, Say). This 

 is one of the most numerous and most noticeable of 

 the parasites of the cotton- worm. It was the species 

 observed by Dr. Gorham and Messrs. Affleck and 

 Glover, and probably also the one spoken of by 

 Mr. Jones. It was first scientifically described by 

 Thomas Say, in 1835, who found it iu Indiana.* 

 He described it under the generic name of Cryptus, 



FIG. 44. Pimpla con- but ** nas since l)een P ut in ^ m P^ *>J Mr - Cresson. 



quisitor. A recent note from Mr Cresson informs us that 



Say made the curious mistake of describing the male as a different 



'Say's original description is as follows : 



C. conqumtor. Black ; tergum, with the posterior margins of the segments, white ; 

 feet honey-yellow ; posterior tibiae and tarsi with black joints. 

 Inhabits Indiana. 

 Body black, punctured; palpi white; thorax, punctures minute; a longitudinal 



