THE OLIVE INSECTS OF CALIFORNIA 



BY E. O. ESSIG 



INTRODUCTION 



As compared with other trees in California, the olive is attacked 

 by comparatively few insects and in many localities is almost entirely 

 exempt from regularly destructive pests. The industry, however, is 

 so large and conditions of insect work so varied that it seems advisable 

 to collect all of the available information regarding the insects which 

 infest this crop in one paper. The subject matter is discussed under 

 the two general heads : I, the more important olive insects in Califor- 

 nia, and II, insects of minor importance to olive trees in California. 

 There is also included at the end a brief discussion of some of the 

 most important olive insects of other states and foreign countries 

 which have not gained access to this state or, as in a few cases, do 

 not attack the olive here. 



The writer is specially indebted to Prof. C. W. Woodworth of the 

 Division of Entomology and to Prof. Frederic T. Bioletti of the 

 Division of Viticulture and Enology for many helpful suggestions and 

 corrections. 



I. THE MORE IMPORTANT OLIVE INSECTS IN CALIFORNIA 



THE BLACK SCALE 



Saissetia oleae (Bernard) 



Figures 1 and 2 



The black scale is the commonest and most troublesome insect pest 

 of the olive in California, but there are many districts which have 

 always been practically free from serious attacks. The young are 

 liable to be killed by hot, dry weather and therefore the insect does 

 not find the climatic conditions of the warmer valleys so favorable 

 to its growth as those along the coast. However, it is gradually 

 encroaching upon territory claimed a few years ago to be absolutely 

 immune because of the hot, dry summers. 



In most other states and especially in Europe, this insect is com- 

 monly known as the olive scale or olive cochineal and has received 

 the specific name oleae from the olive which it commonly attacks. 

 In California, it has always been called the black scale, either because 

 of the dull black color of most of the females or because this insect is 

 the one chiefly responsible for the growth of the black smut fungus 

 over the leaves, stems and fruit of the infested plants. It has one 



