18 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



Pupa (after Greene, 1926): Very thin, shining, transparent, with 

 a yellowish tinge. Antennal capsules large, pointing outward, 

 faintly annulated to the tip; just posterior to the base of these are 3 

 faint ocellar punctures. Thorax slightly longer than wide, smooth; 

 wing pads smooth, reaching to the apex of the third abdominal 

 segment; thoracic spiracles situated on a small elevation; the spiracular 

 entrance is golden yellow, sinuous, and contains a great number of 

 short radiating slits. Abdomen cylindrical, composed of 8 segments; 

 first and last segment without any spines; segments 2-7 with a 

 transverse, dorsal row of reddish-yellow spines just posterior to the 

 middle of the segment; segments 1-7 have a sph-acle on the antero- 

 lateral surface; spiracle small, golden yellow, slightly elevated; last 

 segment roimded at apex and entirely smooth. Length 6.0 mm; 

 diameter of thorax 1.85 mm; diameter of abdomen 1.75 mm. 



Biology. — Larvae have been collected from the follo^ving trees: 

 Ulmus species, Populus species, Robinia species, and Liriodendron 

 tulipifera. The larvae seem to prefer trees on which the bark has 

 become loosened. Malloch (1917) intimates that he foimd the larva 

 of Solva to be predaceous on the larvae of Euxesta, Lonchaea, and 

 Heterominga. Greene (1926) states that the larvae may be predaceous 

 but are usually scavengers. 



As the larva of Solva matures, it forms a pupa within the last 

 larval skin as is the case mth all other stratiomyid larvae; however, 

 before emergence, the puparium splits dorsally down the median line 

 and the pupa forces itself about two-thirds of the way out of the 

 puparium and remains there imtil the adult emerges. The emergence 

 of the pupa causes the head of the puparium to become loose and 

 often completely separated as in the higher flies. Adults of Solva 

 can be found on tree trunks ia June, July, and August. 



Material examined.— Illinois: Rock Island, Apr. 5, 1932, C. O. 

 Mohr, 2 larvae, INHM. Pennsjdvania: Blain, Aug. 6, 1955, F. 

 Craighead, lot no. 55 11825, 6 larvae, 7 puparia from oak, USNM. 

 Wisconsin: Madison, July 1938, Dodge, 23 larvae, 6 puparia 

 from imder elm bark, OSU. 



Subfamily Chiromyzinae 



Although the genus Altermetoponia Miller has been placed in this 

 subfamily, there is some doubt as to whether it should be left here or 

 placed in a subfamily of its owti as Hennig (1952) has done. Because 

 of a scarcity of specimens iti related genera within the subfamily, 

 it has been impossible to make a comparison of characters. Raff 

 (1931) has provided a vague description of the larva of Chiromyza 



