DIESASKS OP CITRUS TREES ] 88 



habits as the purple scale, but it is not found in the 

 orange groves at Malta. 



The Lecanidae are represented by three species of 

 scale insects, viz: Lecanium hesperidum Lin., L. hemis- 

 phaericum Targ., and L. Oleae Bernard, the last two 

 being found also on many trees, shrubs and plants. 

 They have a soft covering which hardens with age, and 

 therefore are more open to the attacks of their enemies 

 than the armoured scale insects already mentioned. 

 Lecanium kesperidum, the Turtle-back scale, (Maltese^ 

 miscta kambija) is fairly common in our groves. It has a 

 greyish lucid covering of an oval form, shaped like half 

 a hemp seed, but somewhat larger, and spotted all over 

 with black. When young it is pale grey, and becomes 

 wrinkled and deep brown with age. It is met with more 

 often on young trees, and occurs in thick colonies cover- 

 ing completely the twig and leaves. It is almost always 

 accompanied by a number of ants busily sucking the 

 honey dew which it secretes abundantly. Young trees 

 infested by this parasite are checked in their growth, and 

 become stunted and sickly, the insect often reappearing 

 on the same tree for two or three years in succession. 



Lecanium Oleae, the black scale, (Maltese = ^^^ 

 seuda koxna) has a round black covering with a marked 

 ridge in the middle, and is from 4 to 5 m.m. in diameter. 

 Its black wrinkled covering makes it look like a grain of 

 black pepper. The young larva is dark red and is easily 

 visible with the naked eye. This scale is very common 

 everywhere in our groves, and is also found on the Olive, 

 stone-fruit-trees, and many ornamental irees and shrubs, 

 as well as on Capsicums and other annuals. Severe attacks 

 are frequent, and result in momentarily checking the 

 growth of the tree and favouring the development of 

 Limacinia Citri (Briosi et Pass.) Sacc. and of L. Penzigi 

 Sacc. the sooty fungus above mentioned. 



Lecanium hemisphaericum (Maltese miscta hamra 

 hoxna), has a round, hemispherical covering of a red- 



