affecting the Potato-crops. Ill 



much mischief in gardens ; and at the close of the year 1845 

 many of them were sent to me as abounding on decayed portions 

 of planted potatoes, and I have met with them likewise about the 

 tubers and in flower-pots, where they burrow in all directions. 

 Some I received in July were about | of an inch long, of an 

 ochreous brown or snuff-colour, and shagreened : the back is 

 slightly convex, with 12 well-defined wrinkled segments and a 

 horny shining head, much narrower than the body, intensely black 

 or inclining to chestnut-colour, and slightly hairy; there are 8 dis- 

 tinct spiracles on each side, the penultimate segment is rounded, 

 with 4 teeth on the margin, and the anal one has 4 smaller teeth, 

 with '2 large spiracles near the base : it has no feet. 



They were transformed to pupae in the earth the beginning of 

 August, and were then yellowish- white ; the thoracic portion was 

 very thick, with 2 horns in front ; the body slender and sub- 

 cylindric, the segments very distinct, with spiracles down the 

 sides, and the tail spiny. 



The flies hatched on the 21st of August, but they abound in 

 fields, hedges, especially under trees, and even in the highways 

 around London, the whole of that month ; and there must be two 

 broods of them, as they are found likewise in May. They belong 

 to the Family Tipulid^, and to the Genus Dilophus. The 

 species was named febrilis by Linnceus, from the generally 

 received opinion in Sweden of these flies resorting to houses 

 where intermittent fevers existed. 



39. D. febrilis is intensely black, shining, and hairy. The 

 head of the Male is hemispheric, and covered with large densely 

 pubescent eyes of a reddish-brown colour; there are 3 minute 

 ocelli forming an elevated triangle near the base : the lip is broad, 

 and the feelers incurved : the trunk is oval and gibbose, with 2 

 transverse rows of minute teeth before : the scutel is short and 

 broad : abdomen sublinear, 8-jointed, the apex clubbed : the 2 

 wings are incumbent in repose, perfectly transparent and white 

 but iridescent, the pinion only is slightly tinged with brown, the 

 costal nervures pitchy, the others very faintly marked ; a radial 

 nervure uniting with the costa at the middle forms a brown spot 

 at the extremity : 2 balancers, with a large compressed brown 

 club : it has 6 long legs ; anterior thighs the thickest, the shanks 

 very short, the apex surrounded by a coronet of teeth ; there are 

 also several short spines outside ; feet slender, 5-jointed, termi- 

 nated by claws and suckers : length 2J lines, expanse 5 lines. 

 The Female is larger and very different, the head being much 

 less, with small oval eyes not meeting on the crown : the abdomen 

 is brownish and elongated, ovate at the extremity but narrowed 

 at the base, and the tip is furnished with 2 minute tubercles : the 

 wings are much longer and very ample, entirely brown, the 



