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THE BIBIONIDA:, 153 
The members of this family frequent meadows, and appear in great 
numbers, such as Bidio. They mostly appear in the spring, but sowe 
are autumnal insects, and they may even appear in midwinter 
(Dilophus). ‘This latter genus also occurs in great abundance in hop 
fields, where the “ fever fly,” as it is called, does great damage. 
Haliday also says they appear plentifully on sand-hills. The genus 
Scatopse may be found in outhouses, on walls and windows, while 
some frequent flowers (.S. xofa¢a), and others are abundant on trees, 
feeding on the honeydew of the Aphis (.S. picea). Many appear in 
swarms or clusters. “In 1862 it (D. febrilis) was recorded.as hang- 
ing in millions on flowers, and in bunches on grasses.”* It is not 
uncommon to find clusters of them under the bark of trees. In 1887 
I noticed this character in particular in a Scatopse at Hastings. It 
appears to be the females that have this gregarious habit ; the males 
may usually be found hovering about in the air ; their flight is slow 
and heavy. Some of this family are double-brooded, such as the 
common fever-fly, which appears in spring and autumn, but the 
majority seem to have only one brood. Although it is a small 
family, and evidently on the decline, the number of specimens is very 
great. ‘They are very abundant all over England, as many as forty- 
two species being recorded, nearly all of which are fairly common 
and some appearing in immense numbers. 
The darve of this family are cylindrical or fusciform maggots, 
living in the earth, in dung, stems of plants, and at the roots (Dé/o- 
phus) destroying the vegetation; the grass roots and corn are 
especially attacked and destroyed (idio and Dilophus), others 
(Scatopse) feed on decaying animal and vegetable substances. The 
maggots occasionally do great damage, as in the case of the fever-fly 
(Dilophus febrilis), to be described later. The larve are furnished 
with twenty spiracles and with transverse rows of hairs ; generally 
whitish-brown in colour, with brown head, which is armed with two 
biting mandibles (27020). 
The /arva of B. pomone (Fig. 1, Plate iii.). This maggot when 
full-grown is about three-fourths of an inch to an inch long, of a chest- 
nut brown colour and somewhat flattened dorso-ventrally. The head 
is much smaller than the body segments and densely chitinous, orna- 
mented with three pairs of large bristly hairs and several smaller ones. 
The body is divided into twelve segments, the first being narrow and 
having two rows of fleshy tubercles; the remaining segments are 
large, and each one with a single row of six tubercles, the twelfth 
* Man. Inj. Insects, p. 129.—Ormerod. 
