Insects, etc., Injurious to the Plum. 



381 



FIG. 252. B. 



YOUNG Aphis pruni. YOUNG Aphis prunifolia. 



(Greatly enlarged.) 



duced by the dull purple " mother-queen " are green, and when they 

 became mature viviparous wingless females they vary from olive- 

 brown to green, the abdo- 

 men has three faint green 

 stripes, antenme olive- 

 brown and cornicles brown. 

 This asexual reproduction 

 of wingless forms goes on 

 for some time and, under 

 favourable conditions, to 

 such an extent that the 

 leaves which have gradu- 

 ally curled up die off. As 

 food supply commences to 

 fail, these lice, instead of turning to wingless viviparous females, 

 enter a pupal stage, rudiments of wings, " wing buds," appearing. 



The pupa is shining green and dull yellowish, the wing cases 

 tipped with dark brown ; green cornicles also tipped with black. I 

 have observed the pupal form in the first week in June, and again in 

 July. Sometimes all on a tree enter this stage at once, at others 

 only a few. 



The winged female coming from the pupa is also viviparous ; in 

 colour she is apple-green, with black head, thorax and antennae ; on 

 the green abdomen is a dark patch and dark lateral spots ; the wings 



are iridescent with brown veins. 



These winged viviparous females 

 fly away. What happens after their 

 leaving the prunes in June we do 

 not know, but they certainly do so 

 and return again in the autumn 

 as winged females which produce 

 young which eventually give origin 

 to males and females. 



The winged male is small, and 

 with a dusky ochreous body, with 

 dark brown head, markings on the 

 thorax, and three on the abdomen. 

 The colour varies considerably, some 

 males being almost black, some 

 wholly black, according to Buckton. 

 The oviparous female is apterous and pale yellowish-green, almost 

 transparent, with brown cornicles. This female, after being fertilised 



FIG. 253. LATER STAGE OF A 



(viviparous female). 

 (Greatly enlarged.) 



