138 



liad ceased to be a larva. The male insect is mucli smaller, and is re- 

 presented in the early stage, before it awakens to winged life, by a 

 white scale, having a black dot at one extremity. Parlatoria Pergandi 

 is a new scale-insect recently imported from Italy. Presently, it is 

 limited to some orange groves at Casal Lia. 



The Ceroplastes Rusci is a scale insect v\hich is commonly met with 

 on the Fig-tree, and is rarely seen on the orange-tree in this island, 

 although in foreign countries it is a n /torious offender. 



The Lecanium hesperidum is a grey coloured scale insect, about the 

 size and colour of a hemp-seed. It has a soft scale which renders it an 

 ea&y prey to its enemies. The same thing may be said of the Lecanium 

 hemisphsericum, a round shaped insect of a rusty colour, having a soft 

 covering like the preceding. 



The Bactylopius destructor, usually known as mealy-bug, is very 

 well described by this name and is a great foe of the orange tree in 

 Northern latitudes. 



The scale insects may be cleared off the orange grove, by sprinkling 

 the trees with petroleum emulsion, or by fumigating the tree with hy- 

 drocyanic acid. But this treatment should be carried out when the 

 larv9D are quitting their mother scale, and unless all orange groves of 

 the same neighbourhood are similarly treated, we shall have a new out- 

 break in a few months. 



The diseases of the orange tree which recognize as their cause the 

 presence of fungus parasites are so numerous, that a descripiion of 

 them would afford matter enough for a large volume. I can only give 

 a brief sketch of three of them. 



Thus the Meliola Penzigi, the black blight of the orange tree, also 

 called Fumago or Capnodium Citri, make its first appearance towards 

 the end of the autumn, as small black dots on the leaves, the twigs and 

 the fruit. These black dots gradually enlarge, and join together, cover- 

 ing the whole surface with a black soot-like substance. Soon after the 

 fungus dies, and in dry weather, separates from the green epidermis, 

 in large crusts. Besides rendering the tree and the fruit unsightly, 

 this fungus really damages the tree, because it closes up the pores of 

 the leaf and deprives it of the full benefit of sunshine. 



Gumming is an infective disease of the orange tree, due to two and 

 probably to more species of fungus (the Fusarium, Fusisporium, Clado- 

 sporium and others.; It is characterized by a gummy exudation from 

 the bark, accompanied by the death of the bark and the wood under- 

 neath it. Gumming or gummosis is a deadly disease which works 

 great havoc in the orange grove particularly in years of drought. It 

 travels up and down the trunk, disfiguring the tree and finally killing 

 it, although in large trees the ultimate fate may be delayed for 5 or 6 

 years. The Seville orange resists this disease better than other kinds 

 of orange trees, as I have known Seville orange trees coming over gum- 

 mosis, and reproducing the bark killed by this disease ; and this is one 

 of the many advantages which the Seville orange presents as a graft- 

 ing stock. 



Polyporus obliquus is also a very fatal and by no means a rare disease 

 of the orange tree. It is characterized by the formation of a round or 

 £>val shaped woody outgrowth from the trunk and large branches whicK 



