98 ILLINOIS BIOLOGICAL MONOGRAPHS (416 



Subfamily Scolioneurinae 



Larvae (Fig. 22) very small; body semicylindrical, somewhat de- 

 pressed, flattened on venter, broader on thorax, tapering caudad, glabrous, 

 greenish, never with bright patterns; segmentation distinct; annulation 

 indistinct, third abdominal segment with two annulets; larvapods rudi- 

 mentary, mere swellings on abdominal segments 2-7, the anal pair adjacent 

 on meson, forming a single protuberance; thorax thickened, prothorax 

 often with distinct dorsal and ventral chitinized shields; thoracic legs 

 small, slender, distinctly five-segmented, directed laterad; head depressed, 

 sub triangular, wedge-shaped in profile, narrower than thorax; mouth- 

 parts flattened and protruding, labium large, with submentum and mentum 

 strongly chitinized; antenna one-segmented; vertical furrows usually 

 wanting; tenth abdominal tergum abbreviated, glabrous; spiracles usually 

 winged; glandubae obsolete; ventral glands wanting; cuticle often with 

 minute dentiform tubercles; leaf-miners. 



The Scolioneurinae is a small subfamily containing six genera, four of 

 which are peculiar to the Nearctic region. All six genera are represented 

 in the North American fauna. Prior to the recognition of the subfamily 

 by MacGillivray, the species belonging to it were referred to the genera 

 Fenusa and Blennocampa. Konow first segregated a species of Entodecta 

 and later more of Scolioneura from Blennocampa, placing them, together 

 with Fenusa and its allies, in other genera of his tribe Blennocampides. 

 Rohwer would separate the genera of the Scolioneurinae from those of 

 the Blennocampinae but unite them with those of the Fenusinae in the 

 tribe Messini of his subfamily Messinae. The close affinity of the Fenu- 

 sinae and Scolioneurinae is evident from the fact that all known larvae 

 of these subfamilies are leaf-miners and that they possess similar types of 

 structural modifications. The definitions here given are based on obser- 

 vations on two American species of Metallus supplemented by writings of 

 European students — Cameron, Brischke, and Zaddach. 



Metallus Forbes 



Larvae small, length 10-13 mm., whitish or pale brownish; body de- 

 pressed, rather stout, mesothorax broadest; pleuron of each segment 

 tuberculate; cuticle with microscopic irregular chitinized dentiform 

 tubercles, those on center of dorsum and venter largest; head directed 

 ventro-cephalad, much narrower than thorax, attached to the ventral 

 part of prothorax; vertical furrows wanting; front twice as long as wide, 

 labrum subtriangu'ar, small; antennae mamma-like; ocellarae incon- 

 spicuous, about one-fifth the diameter of the antennaria; mouth-parts 

 small but distinct, slightly modified; mandibular dentes sharp; maxillary 

 palpi three-segmented, stipes elongate, galea digit-like, slightly curved 



