DOLICHOPODIM. 



231 



found larvae of Medeterus in burrows of Scolytidae, and 

 thinks them predaceous. According to Sharp, the larvae 

 are amphipneustic, 'a cocoon is formed and the pupa is 

 remarkable on account of the existence of two long horns 

 bearing the spiracles, on the back of the thorax; the seven 

 pairs of abdominal spiracles being excessively minute.' 



In adult life all are predaceous, capturing chiefly the 

 minuter soft-bodied flies, which they enclose within their 

 soft labella, after the manner of Scatophaga, while ex- 

 tracting the juices. 



As to their immediate habitat, Dolichopodidae are gen- 

 erally very uniform within the species, but within the 

 genus two or three habitats may be occupied. The fol- 

 lowing list of places preferred is referred to by letter in 

 the table of genera, and may be of use to collectors. 



a. On foliage in shady places. f. On stones in streams. 



b. On foliage in the sun. g. On bark of trees. 



c. On grass. h. On rocks in cold, wet places. 



d. On wet earth at edge of water. i. On sea beaches. 



e. On surface of water. j. On old logs. 



None of the species are attracted to flowers or to light. 



Fig. 90. Dolichopodidae. i, Psilopus unij'asciatus, wing; 2, 

 Liancalus siwi/is, wing; 3, Psilopodinus sipho, wing; 4, Hypocharas- 

 stts, gladiator, wing; 5, Diaphorus spectabilis, wing; 6, Plagioneurns 

 nnivitattus, wing; 7, Xanthochlorns heli'inns, wing; 8, Achalcus n. 

 sp. wing (22 diani.); 9, Asyndetus syntormoides, wing; 10, Tachytre- 

 chus sanus, wing; 1 1, Sccllus I'i.gil, wing; 12, Hydrophorus eldora- 

 densis, wing; 13, Nothosympycnusfrontalis, wing; 14, Pelastoneurus 

 vagans, wing; 15, Gyinnopternus p'hyllophorns^ wing; 16, Argyra albi- 

 citt/s, wing; 17, Mesorhaga albiciliata, wing; 18, Medeterus aurivit- 

 tatus,wing', 19, Thrypticns unllistoni, wing; 20, Dolichopus tenuipes, 

 wing; 2i, Xeurigona later alis, wing; 22, Parasyntormon montiva- 

 guni, wing of male: 23, Sympycnus pugil, wing of male; 24, Rhaphi- 

 11 in lugubre, wing; 25, Aphrosylus prcrdator, wing; 26, Hercostomus 

 unicolor, wing; 27, Pelastoneurus vagans, head; 28, Rhaphium lu- 

 gubre, head of male; 29, Porphyrops effilatus, antenna; 30, Hydro- 

 phorus eldbradensis, head; 31, Pelastoneurus vagans, head of male 

 from in front; 32, Mesorhaga albiciliata, head from in front; 33, Do- 

 lichopus tcnuipes, abdomen of male, side v r iew; 34, Porphyrops effilatus, 

 abdomen of male; 35, Dolichopus idahoensis, hind* metatarsus; 36, 

 Nothosympvcnus fortunatus, front tibia and tarstis of male; 37, Scel- 

 lus virago, front femur; 39, Parasyntormon emarginatum, antenna 

 of male, inner side. 



All wings enlarged nine diameters, except fig. 8, where the corres- 

 ponding size is shown in outline. Figs 36 and 39 after Wheeler, all 

 others by J. M. Aldrich from nature. 



