THE AVOCADO 59 



industry develops its enemies become more numerous. So it 

 has been with the avocado. During the first few years in which 

 this fruit was planted commercially in Florida little injury was 

 caused by parasites, but recently it has been necessary to com- 

 bat vigorously the insects which prey on the tree, and also 

 several fungous diseases. 



In California the avocado has, up to the present, been com- 

 paratively free from the attacks of insect and fungous pests; 

 yet several insects have made their appearance in the orchards 

 and must be watched carefully lest they become so numerous 

 as to cause serious harm. 



Thrips and red-spider are the most common insects which 

 attack the avocado in Florida. Red-banded thrips (Heliothrips 

 rubrocinctus Giard.) and the greenhouse thrips (Heliothrips 

 hcrmorrhoidalis Bouche) feed on the foliage, sometimes causing 

 much damage. Both these species are exceedingly small, 

 soft-bodied, fringed-winged insects, with piercing mouth-parts 

 by means of which they puncture the epidermis and extract the 

 juices from the leaves. They are most destructive in early 

 spring, their numbers being greatly reduced when the summer 

 rains commence. Spraying with nicotine solutions has been 

 quite effective in controlling them. 



The red-spider (Tetranychus mytilaspidis Riley) also does 

 considerable damage during the spring months. This insect, 

 which is scarcely larger than a pin point, can be detected on the 

 foliage without the aid of a magnifying glass because of its 

 bright red color. It feeds on the avocado by piercing the leaf 

 tissues and extracting the plant juices. Often it becomes so 

 abundant as to cause the leaves to assume a brownish, sickly 

 appearance. It occurs commonly in California as well as 

 in Florida, but has not yet been reported as attacking avocados 

 in California. Lime-sulfur mixtures have been used success- 

 fully in combating this insect. For citrus trees, H. L. Quayle 

 recommends commercial lime-sulfur, dry sulfur and hydrated 



