120 BRITISH APHIDES. 



The Syrphus grub will, notwithstanding its vora- 

 city, stand a long fast. Kirby kept one alive for three 

 months without food, and then after giving it a full 

 meal, again he periodically stinted it ; still thus it 

 lived on throughout an entire year. 



Macrog aster liniola^ Curt., and Pachijnenroii for- 

 mosum, Walk., also are parasites which often infest 

 the bodies of the Aj^hidivorous Syrphidce. Many indi- 

 viduals of the last parasite may be detected in one single 

 larva. These insect-scourges must be looked upon as 

 the natural protectors of the Aphis family, and there- 

 fore enemies to the farmer. * 



I have figured the imago of Syrplius halteatus, Ratz.> 

 which is one of the common larval forms. The imago 

 somewhat differs from Curtis' s description of Scceva 

 halteata, and the marking of the body differs also from 

 the figure of Syrphus pyrastri, as given by Westwood. 



Genus XII.— CHAITOPHORUS,t Koch. 

 Boestenlause. Hairy Aphis. 



Rostrum longer than in the preceding genus Hya- 

 lopterus. The second joint as long as the two follow- 

 ing taken together. 



Head without frontal tubercles. Front tufted with 

 bristles. 



Antennge much as in Aphis. Hirsute. 



Abdomen studded with tubercles, each surmounted 

 with a tuft of bristles. 



Cornicles very short, sometimes as short as thick. 

 Mouths often dilated. 



Cauda obtuse and wart-like. 



Legs rather short, clothed with hair. 



Wings veined as in Aphis. 



* Yide Curtis, 'Farm Insects,' p. 80; also Asa Fitch, 'Report on 

 Noxious Insects of New York.' 1856, p. 101. 

 f xa'iTOQ, a bristle; ^optw, I bear. 



