Dolichopodidae. 15 



that they in faet masticate the prey on account of the labrum being 

 very movable, and being used during the feeding. Thiere is also an 

 interesting observation by Wahlberg (Ofvers. Vet. Akad. Forh. I, 1844, 

 37, and Kroyer's Tidsskr. 2, I, 1845, 45) with regard to the prey of the 

 Dolichopodids. The author observed a number of species ofDolicho- 

 podids (together with a few other Diptera) belonging to the genera 

 Hygroceleiithus, Dolichopus, Tachytrechus, Chrysotus, Porphyrops^ Syn- 

 tormon, Hydrophorus, Campsicnemus, Sympycnus and Tinophilus; the 

 species were in activity on a muddy sea-shore, still wet after the 

 water had retracted; they were often seen sitting with the proboscis 

 down to the miid, and when the mouth was retracted, a small 

 whitish thread was drawn up, and eagerly sucked out, These threads 

 proved on closer examination to be Naids, which thus here were the 

 chief food of these flies. The author states, that he did not see the 

 Dolichopodids attack any other insect, but they seized and sucked flies, 

 which he had killed and thrown among them. According to my 

 experience the species are however not often found with prey (I 

 have only seen this on very few occasions), I think because the prey 

 is generally small, and thus quite engulfed during the sucking, so that 

 it is not seen. 



The species of Dolichopodids occur on bushes, in low herbage 

 and grass in woods and outside, generally on damp localities and 

 more or less near water, or at the horders of lakes and streams; 

 some are commen on water piants, others on the wet earth or sand 

 at the horders, or on stones in water; the species of HydropJionis 

 are able to run on the water-surface ; many species are found at or 

 near the shore; some species are generally sitting on tree-trunks; only 

 few occur on more dry localities, on pahngs and walls of houses. 

 Only few species are spring-species, occurring more or less early, the 

 great majority do not occur until in June, The species occur all 

 over the world, also going rather high towards the north; thus 

 two species of DoUchopus are found in Greenland, one of them is the 

 common and widely distributed J). plumipes. 



With regard to the behaviour of the sexes on copulation Aldrich 

 mentions (Amer. Naturalist, XVIII, 1894, 35) a case of courtship with 

 regard to a species of DoUchopus {tenuipes), in which the male has 

 the front tarsi with the last joint dilated, and a species of Hygroce- 

 leuthus (crenatus) with simple front tarsi. The male of the former 

 placed itself in front of the female, beating somewhat with the front 

 legs; then it flew up trying to alight on the female. The male of the 

 latter species was hovering in the air before the female, and then it 

 tried to alight on her. Dahl (Zool. Anz. XII, 1889, 245) observed a 



