229 



chitinized rods with weakly chitinized connecting membrane. Body 

 with very indistinct surface pilosity. First thoracic segment with an 

 indistinct transverse median division. Abdominal segments 2-7 with 

 a median transverse constriction or division. Apical segment with 

 5 stout protuberances. 



Pupa. — Differs from the pupa of Gnophomyia in the structure of 

 the thoracic respiratory organs, which are slender and elongate. The 

 legs also are more elongate than in Gnophomyia. 



HABITS OF LARVAE 



The larvae are found in mud and sand along the margins of 

 streams. They burrow in the wet sand and are able to live under 

 water like the larvae of IJmnophila, though they are less commonly 

 found there. 



HABITS OP IMAGINES 



The imagines are very common throiighout Illinois and usually 

 fly in the late afternoon. They are readily attracted to lights at night. 

 They may feed upon nectar, but the mouth parts are poorly developed. 



Our species occurs also in Europe. 



Helobia punctipennis Meigen 



Limnohia punctipainis Meigen, Syst. Beschr. Eur. Zweifl. Ins., Vol. 1, p. 17. (1818) 



Larva (PI. XXIX, Fig. 6).— Length. 8-10 mm. Pale yellowish 

 testaceous. 



Head (PI. XXXIV, Fig. 18) poorly chitinized, the posterior por- 

 tion consisting of slender blackish rods, the intervening spaces filled 

 with weaklv chitinized membrane; antennae short, 2-jointed. the 

 apical joint very short; maxillary palpi longer than antennae and much 

 stouter; mandibles stout, their lower margin toothed (PI. XXXIV, 

 Fig. 11); labium apparently not chitinized, indistinguishable in my 

 specimens. Body covered with short decumbent pile, which is less 

 conspicuous than in the other larvae of this subfamily. Segments 

 with the usual transverse linear incision on dorsum ; apical segment 

 as in Figure 17, Plate XXXIV. 



Pupa (PI. XXIX, Fig. 7). — Length, 7-9 mm. Color as in the 

 larva. 



Thoracic respiratory organs tube-like, from 6 to 8 times as long 

 as their greatest diameter; prothorax flattened, declivitous, with an 

 elongate, rather broad foveate mark on each side of dorsum ; anterior 

 margin of mesothorax with a slight ridge-like swelling, upon which are 



