59 



hymenopterous parasites, but these natural enemies, do not 

 as a rule become very numerous until the aphis attack is at 

 its height. It must not be thought, however, that they do 

 no good, since by killing off vast numbers of the -aphides they 

 tend to prevent a severe attack the following year. 



Measures of Control. This aphis can be controlled by 

 spraying, but it is of the utmost importance to spray early in 

 the season. When the leaves have once been curled little 

 can be done. Lime- washes applied in late February or March, 

 have been found effective, the later applications giving the 

 best results. The aphides may also be controlled by means 

 of contact insecticides, such as nicotine and soft soap, quassia, 

 and soft soap, or paraffin emulsion, the spray being applied 

 just before the blossom opens or ; after the petals h,ave fallen, 

 but, in the latter case, before the leaves have been curled. A 

 close watch is required in order to discover the attack in its 

 early stages. 



II. MEALY PLUM APHIS. 

 (Hyalopteru's pruni, Fab.) !> 



Nature of Damage. Although serious damage is some- 

 times reported as being due to this aphis, it is, as a rule, far 

 less harmful than the Leaf -curling Plum Aphis. It is seldom 

 abundant on the plums before midsummer, and is found on 

 the underside of the leaves, on the leaf stalks and young 

 growth, but it produces no curling of the leaves (see Fig. 2). 

 It secretes abundant honey-dew, however, which, falling on 

 the leaves and fruit, may do considerable damage. 



The insect may be recognised by its light green colour, by 

 the waxy or mealy secretion with which it is covered, and by 

 the fact that it occurs late in the season and does not curl the 

 leaves. 



Plants Attacked. This aphis attacks plurns of various 

 kinds, greengages, damsons, peach, nectarine, apricot, and 

 other species of Prunus. It is very probable that it also lives 

 on reeds and grasses. 



Life-History. The eggs of the Mealy Plum Aphis are laid 

 on the plum twigs in the autumn and do' not hatch until the 

 end of April or the Beginning of May in the following year. 

 " Mother queen " aphides hatch out from these/," eggs and 

 commence to give birth to 'wingless females which in their 

 turn give rise to additional wingless females. It is not until 

 the middle or end of June that winged forms are produced, 

 and while some of these probably migrate to grasses or reeds, 

 others only fly from one tree to another, ,, or .from one twig to 



