NORTH AMERICAN HYMENOPTERA. 305 



feet large, pale olive, marked with black; abdominal oues small, on joints 611, 

 13, pale green. Body smooth, irregularly o-annulate, the creases like slight folds ; 

 shining blackish olivaceous, with a series of lateral pale orange spots, distinct 

 only centrally. The spots are above the subventral fold on annulets 2 and 3. 



Larvffi vary in shade, some are blacker than others, and the orange spots vary 

 in distinctness. The larvse scratch the leaf with their anal prongs and make a 

 rasping sound. 



Fifth stage. — Width of head 1.4-1.6 mm. As before, slaty black, except the feet ; 

 lateral orange patches on joints 3-12 ; the two median annulets have somewhat 

 corneous, dorsal, transverse areas, shining, but concolorous with body. Feet all 

 pale watery. Two days after molting the'larvfe began to turn shining and livid 

 with a pale dorsal streak anteriorly and entered the ground to spin their cocoons. 



Food-plants. — Found on willow (Salix babylonica) in Central 

 Pai-k, New York, and on poplar (Po/>»7».'5' graudidentatus) at Platts- 

 burgh, N. Y. [The latter produced lomhardus.'\ 



The characteristic larva of this species has been described in Har- 

 ris' " Entomological Correspondence," p. 270, and in " Insect Life," 

 i, p. 33, and quoted in the " Fifth Report U. S. Ent. Commission," 

 pp. 524 and 588. 



Male flies emerging the same season were determined by Mr. Mar- 

 latt as N. ventralis, but male from pupie which had hibernated were 

 named " Pteronus lombardas Marlatt MS." I have not as yet bred 

 any females, and suggest the seasonally dimorphic relation of these 

 two forms by showing the aj^parent identity of the larvje. 



Xematns Marlattii n. sp. 



Larva. — Solitary, eating on the edge of alder leaves ; sitting on the edge or in 

 a hole, the posterior half of the body curled spirally. Head full at vertex, round, 

 clypeus rounded, distinct : pale, shining, greenish brown, with a clouded, deep 

 black longitudinal patch at the vertex and one laterally over the black eye : cly- 

 peus and mouth rather darker brown ; width 1.2 mm. Thoracic feet moderate, 

 pale ; abdominal ones on joints 6-11, 13 ; segments moderately 4-annulate, smooth, 

 not shining, subtranslucent leaf-green, dorsal vessel scarcely showing; a broad 

 subdorsal blackish green band, broken into a series of segmental patches, extend- 

 ing down to enclose the spiracles ; double subventi'al ridge also blackish, but dis- 

 tinctly spotted with pale, corresponding to the obsolete tubercles; the subdorsal 

 patches also contain pale spots corresponding to tubercles on annulets 2 and 3, 

 but less distinctly. 



Imago. — Length 25 inch., expanse .5 inch. ; antennie nearly three-fourths the 

 length of body. The coloration corresponds with Norton's description of ven- 

 tralis, but the orbits are continuously pale. 



A single female was determined by Mr. Marlatt as N. ventralis 

 Say, and indeed corresponds closely with the description. However, 

 as the larva is very different, the species must be separate. 



TKANS. AM. ENT. SOC. XXII. (39) SEPTEMBER, 1895. 



