538 



PLUM AND CHEERY APHIS (Myzus cerasi). 



This aphis closely resembles the peach aphis in general colouring 

 and shape. It appears as soon as the leaves of the trees on which 



it feeds expand and multiplies very 

 rapidly, being hatched from eggs 

 deposited on the branches during 

 the previous fall. They are not so 

 abundant in midsummer, but 

 become numerous again in the 

 autumn, when the sexes appear 

 and deposit their eggs at the base 

 of the buds and cracks of the 

 bark, where they remain during 

 the winter, and hatch the follow- 

 ing spring. They secrete a large 

 amount of honey dew, which at- 

 tracts numerous flies and ants. 



Remedies. Use Nos. 7, 8, 9,. 

 14, 15, 19, or 20 (see pp. 490-492). 



ORANGE APHIS (Siphonophora 

 citrifodli, Ashm). 



This insect attacks the young 

 wood of the orange in the spring, 

 a Showing aphis on flower stem of cab- covering the trees so thickly that 



. b The winged louse (natural size), thev appear Quite black. ^ 

 e same enlarged; colours, greenish - J J F . - 1 



c Th 



yellow, d Wingless female. 



of insect, 

 black. 



Colour 

 brownish to shiny 



Remedies. Use Nos. 7, 8, 14, or 20. 



Natural Enemies. This species, as well as the plum and cherry 

 aphis, have many natural enemies, which aid greatly in keeping 

 them in check. In fact, were it not for these natural checks to aid 

 man in preventing the destruction of his plants, all his efforts would 

 prove unavailing. Among the most active in this warfare are the 

 parasitic flies, which are mostly very small and with four 

 transparent wings. They lay a single egg on a louse, which hatches 

 and produces a maggot in the interior of the .host, and which feeds 

 on the juice of the louse until it cha.nges to a pupa, from which it 

 emerges through a small hole cut in the body of the louse. A close 

 inspection of a family of plant lice will disclose many with this hole 

 in them. A parasitised louse may be told, even before its death, 

 by the swollen abdomen, which will distinguish it from its 11011- 

 parasitised mates. 



One of the most numerous of the predaceous insects is the 

 Syrphus or flower flies, which may be seen hovering around 



