192 Journal New York Entomological Society. [Voi. xxiv, 



in the male genitalia. The larvae, according to Mr. Timberlake, 

 may be found in tubular cells beneath the bark and cause hardly any 

 external swelling. 



Exuvium. — Length 4 mm. Whitish transparent, the antenna] cases hardly- 

 extending to the base of the abdomen, the wing cases to the third abdominal 

 segment, and the leg cases of presumably the fore, middle and posterior legs 

 extending to the fourth, fifth and seventh segments, respectively. The dorsum 

 of the abdominal segments with transverse rows of minute spines. 



Male. — Length 3 mm. Antennae extending to the third abdominal seg- 

 ment, sparsely haired, yellowish brown; 19 segments, the fifth with a stem 

 one-half the length of the cylindric basal enlargement, which latter has a 

 length one-half greater than its diameter; terminal segment produced, taper- 

 ing slightly to a narrowly rounded apex and with a length two and one-half 

 times its diameter. Palpi obscure in the preparation. Mesonotum reddish brown. 

 Scutellum and postscutellum lighter. Abdomen yellowish orange. Legs pale 

 straw ; claws moderately stout, evenly curved, the pulvilli as long as the claws. 

 Genitalia ; basal clasp segment stout ; terminal clasp segment moderately long 

 tapering strongly distally ; dorsal plate broad, broadly and triangularly emargi- 

 nate, the lobes broadly expanded, broadly oval and sparsely setose; ventral plate 

 moderately long, broad, deeply and roundly emarginate, the lobes moderately 

 short, broad and tapering to a broadly rounded apex. Harpes short, broad, 

 obliquely truncate and at the internal angle a stout, quadrate, chitinous tooth ; 

 style short, stout. 



Female. — Length 3.3 mm. Antennae extending to the first abdominal seg- 

 ment, sparsely haired, yellowish brown ; 20 sessile segments, the fifth with a 

 length one-fourth greater than its diameter, the terminal segment slightly 

 produced, narrowly oval, with a length over twice its diameter. Palpi ; first 

 segment short, quadrate, the second a little longer, broader, the third a little 

 longer and more slender than the second, the fourth about twice the length 

 of the third, moderately stout. Ovipositor about three-fourths the length of 

 the abdomen, terminal lobes short, broadly oval and sparsely setose. Color 

 characters in both sexes largely conjectural. Type Cecid. 1646. 



Key to the Species of Di.\rthronomyia. 



a. 17 or 18 antennal segments, the fifth in the male with a stem three-fourths, 

 and that of the female with a stem one-third the length of the basal en- 

 largement, respectively. 

 b. Mesonotum dark reddish brown, the abdomen reddish brown; terminal 

 antennal segment of the male greatly produced ; length, male 2 mm., 

 female, 3 mm. Reared from a variable monothalamovis or poly- 

 thalamous, globose leaf bud or rosette gall or a bladdery leaf gall on 



Artemisia tridentata artemisiae Felt. 



bb. Mesonotum dark brown, the abdomen pale orange ; terminal antennal 

 segment of the male usually reduced. Reared from an irregular, oval, 



