DILOPHUS. 177 



thickened, the 4th and 5th narrow, subequal. Antennae sliort 

 and rather thick, ten- or eleven-jointed ; scapal ones slightly 

 differentiated, the others transverse, flattened bead-shape, the last 

 one flatly conical ; the terminal joints so closely applied to one 

 another as to be difficult to distinguish. Thorax' very arched, 

 produced and emarginate on anterior margin of dorsum in the 

 form of a conspicuous transverse ridge, with a row of short tooth- 

 like points ; a second similar ridge before the middle of the 

 dorsum. Scutellum semicircular, broad, short. Ahdomen of seven 

 or eight segments, elongated. Genitalia of male rather large and 

 prominent, the tip of the abdomen generally curved upwards. 

 Legs robust ; femora, especially fore pair, thickened ; fore tibiae 

 with a circlet of spines at the tip, in addition to a few spines 

 around its middle ; middle and hind tibiae \\ii\\ short apical 

 bristles ; metatarsus of hind legs shorter than the remaining 

 tarsal joints taken together ; claws and pulvilli large, empodia 

 distinct. Wings of moderate size, or comparatively large. 

 Auxiliary and Ist longitudinal veins as in BiUo ; 3rd sharply 

 angled near the base, thence running to the costa some distance 

 in front of the tip of the wing. Anterior cross-vein placed at the 

 angle ; 4th vein forked. Posterior cross-vein at fork of 4th, 

 always distinctly beyond 1 he anterior cross-vein ; 5th vein forked, 

 6th vein shortened, 7th absent. Aluhe prominent. 



Range. Dilophns occurs throughout the world, though the species 

 are less numerous than in Bihio. 



One very common European species, D. febrilis, L. (vulgai^is, 

 Mg.), (so called from a supposed connection between this fly and 

 the occurrence of fever, a supposition which probabl}' has no 

 foundation), appears occasionally in immense swarms, and possibly 

 other species ma}^ be found in the East with a similar habit. 

 Such a swarm occurred in England in 1862, 



Life-history. The larva of D. febrilis is apodal, cylindrical, 

 covered with stiff bristles, the head chestnut-brown. The larva 

 lives in various substances. Oui'tis says it is found in cow- and 

 horse-manure, and Theobald has reared the species from the 

 latter. Miss Ormerod records it as feeding on hop-stems and 

 the roots of grasses, corn and various plants. The pupa is whitish 

 or pale broA\n. The perfect insect emei-ges in May, and there 

 is a second brood in the autumn. It is generally distributed, but 

 seems partial to greenhouses and conservatories, especially those 

 containing vines.* 



Tlie synonym Philia,Mg., erected in 1800 without any species, 

 cannot take the place of Dilo/)hus, which, although it was proposed 

 in 1803 without an attendant species, was justified a year later 

 by the allotment of three species in Meigen's " Klassification, etc." 



* The above species is referred to at some length, although not Oriental, on 

 account of the distinct economic importance of the genus, and because the 

 life-bistoi-y is not known of any indigenous S23ecies. The habits of Indian 

 species are likely to be similar. 



