r. CORDON HEWITT. 
85f) 
of the tliorax being blackish with three black longitudinal 
stripes; the frontal region is very narrow; the abdomen is 
grey with a dark median stripe. The average length of the 
body is 5 mm. 
In the summer they are common and may be found in the 
neighbourhood of manure. The eggs are laid in this substance, 
especially in horse-manure. The Larvse have also been 
found feeding on the roots of various cultivated cruciferous 
plants, from which the insect has derived the name “root- 
maggot.” The eggs hatch out from eighteen to thirty-six 
hours after deposition. 'J'he first larval stadium lasts twenty- 
four hours, the second forty-eight hours, and five days later 
the larva changes into a pupa, the whole larval life occupy- 
ing about eight days. The pupal stage lasts ten days, so that 
in warm weather the development may be completed in nine- 
teen to twenty days. The full-grown larvte measure 8 mm. 
in length, and may be distinguished by the tubercles sur- 
rounding the caudal extremity. In this species there are six 
pairs of spinous tubercles surrounding the posterior end and 
a seventh pair is situated on the ventral surface posterior to 
the anus. The tubercles of the sixth pair, counting fi’om the 
dorsal side, are smaller than the rest and are bifid. The 
arrangement of the tubercles can be seen in fig. 2. The 
anterior spiracular processes (fig. 3) are yellow in colour and 
have thirteen lobes. 
(6) Stomoxys calcitrans Linn. 
The species is common, especially in the country from 
July to October, and during these months it may be often 
found in houses, although Hamer’s observations (1908) 
appear to indicate that the presence of cowsheds, in which 
they occur in large numbers, does not affect their numbers 
in houses. I have found 8. calcitrans in large numbers 
in the windows of a country house in March and April, 
and it may be found frequently out of doors on a sunny 
dav in May, and throughout the ensuing summer months. 
It is normally an outdoor insect, but appears to seek the shelter 
