310 ATHALIA SPINARUM. 



splashed with grey ; they are almost hid by the over- 

 hanging folds of the body. 



The pupa is greyish-white. 



The cocoon is oval and is formed of grains of earth 

 closely agglutinated together. Externally it is rough ; 

 internally smooth and shining. 



The larva eats night and day, and seems to delight 

 in the hottest sunshine, in which it basks curled up on 

 the upper surface of the leaf. It lives as a larva about 

 nineteen days. 



There are usually three broods in the year ; the first 

 appears in early summer, the second at the end of 

 July and beginning of August ; these become developed 

 at the middle of September, and give issue to another 

 brood which feed on sometimes to the end of 

 October. 



Although the larva is principally known from the 

 ravages it commits on the turnip, yet it also feeds on 

 other cruciferous plants such as Sinapis arvensis, 

 Barbarea and Sisymbrium. Indeed, Sinapis is pro- 

 bably the natural food plant, and according to Newport 

 it prefers it even to the white turnip. The last- 

 mentioned author has found them on Sinapis in great 

 abundance, feeding upon the leaves and flowers. 

 Newport says also, that if there be any charlock in the 

 same field with the turnip, the larva will attack the 

 former plant first ; and if there be plenty of the weed 

 they will stick to it and leave the turnips alone. 



The flies make their appearance in May, then in 

 July, August and September with the second and third 

 broods. According to Curtis they live from twelve 

 to fourteen days. They fly in the sunshine and fre- 

 quent flowers, showing a preference for roses, accord- 

 ing to some authorities. Hence the species was named 

 Gentifolice by Panzer. When touched or alarmed 

 they tuck the antennae and legs close to the body and 

 drop to the earth, where they remain motionless until 

 the danger has passed away. During cloudy weather 

 they remain seated on the underside of the leaves, 



