92 MISC. PUBLICATION 17 4, U.S. DEPT. OF AGRICULTURE 



like rnesoscutura ; propodeum broad, without an apical neck and without 

 carinae, the lateral folds represented by a large smooth fovea on each side 

 of the middle about half way between the median line and the spiracles, 

 spiracular grooves absent, spiracles elliptical, surface of propodeum sculp- 

 tured like scutellum but with punctures a little smaller; mesopleura sculp- 

 tured like propodeum but with a smooth area along the dorsal margin ; meta- 

 pleura weakly punctate. Legs normal; the hind tibia with a single spur; 

 tarsi 5-jointed, the posterior basitarsus short, not longer than the two fol- 

 lowing joints combined. Fore wing extending a little beyond the apex of abdo- 

 men, approximately two and one third times as long as broad, its surface 

 bare from base to a little beyond the apex of submarginal vein except for 

 a few cilia in the costal cell, marginal cilia very short; marginal and post- 

 marginal veins subequal, the stigmal approximately three fourths as long 

 as marginal. Abdomen about as long as thorax, broadly ovate, as broad as 

 or a little broader than the thorax, sessile, practically smooth, the apical 

 segments with some very faint reticulation ; ovipositor sheaths slightly exposed 

 at apex. 



Color of head and thorax metallic dark green, the abdomen usually dark 

 brown or blackish with a strong metallic luster but frequently with a reddish 

 testaceous spot basally, this spot sometimes embracing most of the basal half of 

 abdomen ; antennae brownish testaceous with the scape, pedicel, and club usually 

 somewhat paler testaceous ; mandibles reddish testaceous with their apices 

 dark brown ; legs with all coxae metallic green, all femora usually dark brown- 

 ish or fuscous but frequently all testaceous, the tibiae and tarsi pale yellow- 

 ish with the tarsal claws dark brown; wings hyaline, the venation brownish 

 yellow. 



Male. — Length 1.8 to 2.6 mm. Antennae 13-jointed, moderately long and 

 slender, the flagellar joints and club joints evenly clothed with hairs which 

 are approximately as long as the joints are thick ; pedicel a little longer than 

 thick ; ring joints transverse but distinct ; funicle 6-jointed, the first funicle 

 joint usually nearly three times as long as broad, two following joints suc- 

 cessively a little shorter, the fourth and fifth subequal to each other, each a 

 little shorter than the third and a little longer than the sixth, which is usually 

 about one and one half times as long as thick ; club 3-jointed, long oval, a little 

 longer than the two preceding joints together; the joints separated by sutures 

 but not distinctly set off as are the joints of funicle. Thorax a little more slender 

 than in female. Abdomen not so long as thorax, elliptical, and usually not so 

 broad as the thorax. Antennal flagellum entirely and frequently the scape 

 and pedicel black or blackish, the scape usually pale at base and frequently 

 mostly pale. Other characters as in the female. 



Description drawn from specimens reared from the hessian fly. 



REVIEW OF LITERATURE 



Merisus destructor was originally described by Thomas Say in 

 1817 under the name Ceraphron destructor. Say recorded it as a 

 parasite of the hessian fly and described its oviposition and emer- 

 gence from the puparium of its host. In 1840 Westwood expressed 

 the opinion that the species was one of the Eulophides. Herrick 

 in 1841 referred it to the genus Eurytoma and stated it to be the 

 principal parasite of the fly; the following year Harris treated it 

 under the same name, giving a short account of its habits. In 1846 

 Curtis placed it in the genus Pteromalws, on the authority of West- 

 wood, and in the second and third editions of Insects Injurious to 

 Vegetation by Harris, published, respectively, in 1852 and 1862, 

 it was treated under the name Rhaphiteles (Storthycpocerus) destruc- 

 tor. The species was next referred to the genus Semiotellus by Fitch, 

 who in 1862 discussed fully his reasons for so doing and gave a good 

 description of the adult together with some observations on its habits 

 and stated that it was the most important parasite of the fly. Cook 

 in 1877 and Packard in 1880 and again in 1883 redescribed the species 



