THE CABBAGE APHIS. 



LlFE-HISTORY OF Aphis pruni, Reaumur. 

 - Eggs, 



21 



Larvae. 



Wingless viviparous 

 females. 



Young 



which develop into further 

 apterous viviparous females, 

 which again produce young 

 and so on for a series of 

 generations 



Pupae. 



After fertilisation. 



Winged males. 



Apterous oviparous 

 females. 



Pupae.- 



Successive generations of 

 apterous viviparous females. 



Young. 



Viviparous winged 

 females. 



THE CABBAGE APHIS. 



Aphis brassicae. Linn. 



During the past season this Aphid has proved a very serious 

 pest ; and frequent applications have been received for information. 



LIFE-HISTORY, ETC. 



The eggs are deposited on the under surface of the leaves of 

 cabbage, Brussels sprouts, and other cruciferous plants at the end 

 of October or early in November, and hatch out early in May. It 

 is not until the year has well advanced that they do any consider- 

 able damage, although plants received from Cheshire in July were 

 blistered all over, most of the leaves having many yellow patches 

 on them. 



In the early part of the year the larvae are covered with a 

 mealy-like substance, and seem to spread very slowly. 



In Staffordshire and Warwickshire there was an active migra- 

 tion late in the summer from such plants as the shepherd's purse 

 (Capsella bursa-pastoris\ the charlock or wild mustard (Brassica 

 sinapsis\ etc. Indeed, it would seem as if they prefer the culti- 

 vated plants in the autumn. Here they excrete large quantities of a 

 sticky honey-dew, which covers the leaves and stems, making most 

 plants unmarketable, and, if largely infested, killing them. 



