DISEASES OF CITRUS TREES ] 87 



St. Julians, whence it spread to Sliema. This insect 

 attacks not only the orange-tribe but also many other fruit 

 and ornamental trees, whether evergreen or deciduous, 

 and many shrubs and annuals as well as vegetables in the 

 kitqhen garden. Fortunately it is kept thoroughly in 

 check by its natural enemy, Novius (Vedalia) cardi- 

 ndlis, but for which the cultivation of Citrus trees would 

 become commercially impossible. 



The mature females of Icerya Purchasi are mostly 

 of an orange red colour, with white and green patches. 

 They have six black legs, and two nine-jointed 

 antennae of the same hue. The eyes are black. The 

 dorsal surface is always covered with a white or 

 yellowish mealy powder. Tufts of yellowish waxy 

 filaments are secreted upon the back and along the 

 sides. Between the dorsal and lateral masses of tufts, 

 the body is naked, so that on both sides there is an 

 orange red line which breaks the yellowish hue of the 

 tufts. On the posterior half of the margin of the body 

 there is a row of tubercles, from each of which a cottony 

 cord is secreted. These cords are prolonged backwards 

 simultaneously, and parallel to each other, and the 

 whole form a spacious bag into which the orange red 

 minute ovoid eggs of the insect, numbering about 500 

 are deposited. On the under-side of the body, between 

 the first pair of paws is found the beak or sucker deeply 

 fixed into the bark. The adult insect rarely stirs from its 

 place, although it does not lose its legs as the armoured 

 scale insects. The insect and its bag may measure from 

 i to 2 c.m. in length. The young larva is very active, 

 and of a pale red colour, but when it begins to secrete 

 the tufts of waxy filaments all its activity ceases. The 

 Icerya lives upon the stem and branches up to the 

 smallest twigs upon which it assembles in clusters, 

 completely hiding the twig. Like other scale insects it is 

 parthenogenetic and has three or four broods in the year. 

 The male insect appears only in autumn, and is a minute 



