DISEASES OF CITRUS TREES ] 79 



species of Aspidiotus, and is of a uniform rusty red colour, 

 with a shining yellow dot or navel in the centre. This 

 scale is one of the most dangerous. It increases enor- 

 mously, covering with its red scales the old stems as 

 well as the green branches, the foliage and the fruit. 

 Rose-bushes and other ornamental shrubs are soon 

 exhausted and killed, even by a comparatively mild 

 attack. In sheltered and sunny situations an attack of 

 this insect on Citrus trees often assumes a character of 

 great virulence, and is usually followed by the death of 

 large branches, and of the tree itself. 



Parlatoria Pergandii Comstock, the chaff scale, is 

 a round or slightly oval scale, hardly reaching i^ m.m. 

 in length, of a light brown colour. It has at one of its 

 ends a small elliptical shield of a darker colour, which 

 is the first larval skin. The upper surface is marked 

 by small ridges forming a series of ellipses one within 

 the other, the first shield being their common focus. 

 Under the first shield is found the head of the insect with 

 its beak embedded in the green tissues. The male insect 

 has a much smaller elongated scale of a white colour, 

 but the first shield is dark as in the female. This scale 

 lives upon the trunk, the large branches and the twigs, 

 but seldom on the leaves and the fruit, and does not 

 appear to be very virulent. The chaff scale has now 

 spread to most groves of the Island, but so far has not 

 given cause of complaint. 



According to Hubbard an unknown species of 

 Aphelinus eats the eggs and sometimes the body of the 

 chaff scale, and by this means a high percentage of the 

 scale is destroyed. When the Aphelinus completes its 

 metamorphosis, it eats away a hole in the scale and issues 

 forth to winged life. It is very likely that the chaff scale 

 in these Islands is kept in check by some such benefi- 

 cial insect. 



A far more dangerous insect pest is Parlatoria Lu- 

 casi Targ-Tozz., or Parlatoria Zizyphi Lucas, a native 



