76 



Fig. 82. Purple scale. 



Enlarged. (Imperial Dept. Agric.) 



layer several scales thick, or in other cases they may be 

 scattered almost singly. This scale is attacked by lady- 

 birds, parasitic Hymenoptera and parasitic fungi. The 

 most active lady-birds in this connexion are small insects 

 about the size of the head of a pin, or a trine larger. These 

 insects are of the typical lady-bird shape, dark-brown, 

 black, or steely-blue in colour, and may often be seen walking 

 about amongst the scales and feeding on them. The purple 

 scale is attacked by two species of fungi, the red-headed 

 fungus (Sphaerostilbe coccophila) and the white-headed 

 fungus (Ophionectria coccicold). The former of these is well 

 distributed throughout the West Indies and probably exerts 

 a considerable degree of control over the purple scale. 

 Ophionectria occurs in Dominica only. Parasitic Hymenop- 

 tera are fairly abundant throughout the West Indies. 

 Scales which have been attacked by these insects can 

 generally be distinguished by a small round hole through 

 which the adult parasite has emerged. 



THE OKANGE SNOW SCALE (Chionaspis citri, Comst.). 



The orange snow scale (Fig. 83) is probably well 

 known to all growers of citrus trees, occurring as it does in 

 considerable numbers on the bark of the stem and branches of 

 nearly all such plants. It often seems to form a distinct 

 covering or layer over the bark. The female scale is pear- 



