194 REPOET UPON COTTON INSECTS. 



parasite proved to be a new species, and consequently the following 

 scientific description of it has been published by Professor Riley : 



1. TKICHOGRAMMA PRETIOSA, n. sp. Length about 0.3 mm . Yellow, the eyes red, 

 the wings hyaline. Head wider than the thorax ; antennas 5-jointed, joints 3 and 4 

 in the $ forming an ovate mass and together shorter than joint 2; joint 3 large, thick- 

 ened and very obliquely truncate ; in the $ joints 3, 4, and 5 form a more or less dis- 

 tinct, elongate club, beset with long bristles. Hairs of the wings arranged in about 

 fifteen lines. Abdomen not so wide as the thorax, but as long as the head and thorax 

 together; in the 2 the sides subparallel, and the apical joint suddenly narrowed to a 

 point. Described from numerous specimens reared from eggs of Aletia argillacea. 



Differs from Tricliogramma minuta, Eiley (Third Eep. Ins. Mo., p. 158, fig. 72, $ ), in 

 its smaller size and uniform pale yellovr color, and also in the form of the third and 

 fourth joints of the antennae. As defined and figured by Wcstwood, the antennae of 

 Tricliogramma are G-jointed. Walker, in his "Notes on the Chalcididse," pt. vi, p. 105, 

 employing Forster's characters, says the antenna are 8-jointed; but an examination 

 of the figure of the type (Triclwgramma evanesccns, 1. c., p. 114) shows that one of the 

 joints counted is the "annulus" above the scape, which I do not consider to be a true 

 joint, and that what I have indicated as the apical joint, in agreement with West- 

 wood, is represented in that figure as three coalesced joints. I have proposed the 

 generic name of Pentarthrum for minuta in MS. now in Mr. Scudder's hands, but 

 until the allied genera are better characterized than at present it is best to use the 

 old genus Trichogramma. 



With the other twelve parasites the egg is laid upon the larva of 

 Aletia, and the perfect insect emerges either from the larva or from the 

 pupa. Three of these species belong to the same family as the egg-para- 

 site just mentioned, namely, to the Ghalcldidae. 



THE OVATE CHALCIS (Chalcis ovata, Say). This species seems to be 

 one of the most abundant parasites of the cotton- worm in many parts of 

 the South. It is one of the largest of its family, measuring over one- 

 fifth of an inch (5 inm ) in length. The glassy appearance of its abdomen 

 and its swollen hind thighs gives it a characteristic look, and renders it 

 impossible to mistake it for any other cotton-worm parasite. From the 

 4th of August until the 10th of September these little fellows were con- 

 tinually issuing from the chrysalides sent for breeding purposes. There 

 may have been one brood previous, and there probably was one later, 

 the chalcid wintering in the pupa state within the chrysalis of the 

 cotton-worm. The parent fly lays her eggs upon the backs of nearly 

 full-grown cotton-worms, probably more than one egg upon each indi- 

 vidual, although we have never observed more than one of these para- 

 sites to issue from a single worm. The young larvae feed upon the 

 worm's internal parts, choosing by preference the fatty tissue, and avoid- 

 ing all vital organs until they become full-grown. During this time 

 the cotton- worm has probably attained its full growth and webbed up. 

 The parasite eats its host out pretty thoroughly before undergoing its 

 own transformations. Both of its changes from larva to pupa and from 

 pupa to fly are undergone within the dead chrysalis of the cotton-worm, 

 and the perfect fly gnaws a round hole near the head of the chrysalis 

 to make its exit. An examination of many chrysalides from which these 

 parasites have issued shows that the hole of exit is invariably near the 



