UNITED STATES DEPARTMEiNT OF AGRICULTURE 



BULLETIN No. 1035 



Contribution from the Bureau of Entomology 

 L. O. HOWARD, Chief 



J^^%J-U 



Washington, D. C. 



PROFESSIONAL PAPER 



February 17, 1922 



THE RED SPIDER ON THE AVOCADO. 



By G. F. MozNETTE, Assistant Entomologist, Tropical and Subtropical Fruit 



Insect Investigations. 



CONTENTS. 



Page. 



Inti-oduction 1 



Economic importance 1 



Nature of injui-y to foliage 2 



Food plants and distribution 2 



Description and habits 4 



Biological data 7 



Page. 



Predatory enemies 9 



Spraying- experiments 11 



Spray rod versus spray gun l.T 



Cultural methods in the grove 14 



Recommendations 15 



INTRODUCTION. 



The red spider Tetranychus yothersi McG, is one of the fore- 

 most enemies of the avocado and attacks a number of other plants 

 and fruit trees in Florida. It was recognized by avocado growers 

 as an important enemy of this fruit as early as 1909, and since that 

 time the damage caused by it has become more pronounced each 

 year. This bulletin records the work with this spider during the 

 years 1918 and 1919 and the results of cooperative spraying experi- 

 ments in connection with the station established by the Bureau of 

 Entomology in 1917 at Miami, Fla., for the investigation of various 

 insect enemies of the avocado and other subtropical fruits character- 

 istic of that region. 



ECONOMIC IMPORTANCE. 



In groves where the red spider is abundant the trees frequently 

 become defoliated prematurely during the winter season. This 

 generally results in an abnormal development of bloom the following 

 spring and the weakened trees are unable to set and hold a full crop 



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