DISEASES OF CITRUS TREES ] 75 



Other powerlul enemies of the Aphis are the so-called 

 Aphis-lions, Chrysopa Citri and Chrysopa per la. They 

 are Neuropterous insects about i c.m. in length. They 

 are of a lively green colour having four lacy transparent 

 wings of the same size. They have green antennae, 

 red eyes and patches of silvery lustre on the thorax. 

 Their green nimble larvae as well as the perfect insects 

 are very voracious and feed with great complacency 

 on the Aphis, going over from one twig to another in 

 search of their victims. Their greenish white eggs are 

 born on stalks or pedicels \ to i c.m. in length, laid 

 in lines along the margin of leaves on twigs infested by 

 the Aphis. Hubbard mentions Chrysopa oculata having 

 the same habits as the foregoing, devouring the Aphis 

 and larvae of scale insects in the orange groves of 

 North America. H enter obius and l j socus are two other 

 Neuropterous insects having the same habits as the 

 Chrysopa, but are of rarer occurrence. The ladybirds 

 which will be described later on, particularly Coccinella 

 septempunctata, are useful allies against the Aphis, in 

 the same way as against the scale-insects. When the 

 ladybirds make their appearance on a tree infested by 

 Aphis we are sure to see the parasites disappear in a 

 few days. Spraying with petroleum or kerosene emulsion, 

 with tobacco decoction, wood ash-lye, or dusting with 

 sulphur containing 5 % of sulphate of copper, have 

 been tried with success. An excellent preparation for 

 this purpose is Schloesing's precipitated sulphur with 

 nicotine, particularly for young trees badly infested. 

 Dusting once or twice with this preparation soon clears 

 all traces of the Aphis, without causing the least injury 

 to the tender growth. 



The cotton-stainer of the United States, Disdercus 

 suturellus, punctures and destroys the fruit when ripe. 

 It is really a parasite of the cotton plant, and takes 

 to the orange groves after the cotton harvest. It is not 

 present in Europe. 



