Reports to the Board of Agriculture. 149 



Life-history. 



This aphis first makes its appearance in the early spring, when 

 we observe small green lice here and there on the young leaves. 

 These have come from eggs that have remained all the winter upon 

 the plum trees. These lice rapidly grow into the wingless viviparous 

 females, large Aphides, varying in hue from green to olive brown, 

 and the abdomen with three faint green stripes ; antennre olive 

 brown, cornicles brown ; the whole body above and below is covered 

 with a mealy down. 



These apterous females soon commence to produce living young, 

 which rapidly mature and produce other young. This asexual 

 reproduction of wingless forms goes on for some time and under 

 favoural)le conditions to such an extent that the leaves which have 

 gradually 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 antennse ; 

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

 wings are iridescent with Ijrown veins. 



These winged viviparous females fly about and settle upon other 

 trees and set up fresh colonies, producing living young, which 

 grow into npterous viviparous females which carry on rapid repro- 

 duction like the first series. 



In the autumn the pupal stage is assumed again, but from the 

 pupfe now come winged males and wingless oviparous 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 apterous oviparous female is pale yellowish-green, almost 

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

 by the male, deposits little shiny black eggs at the base of the buds 

 and on the twigs. Egg-laying may commence early in October and 

 goes on till November. These eggs usually hatch at the beginning of 

 April, but I have observed the lice as early as March. 



