THE ORANGE THRIPS, 9 



before eggs were deposited by the newly formed adults, made a 

 total of 18.G8 days for May to August, inclusive. 11)09. For the 

 months April to August, inclusive, 1010, this period was 23 days. 

 The length of the life cycle of S individuals actually recorded from 

 the egg, upon potted plants, allowing 3 daj^s, as before, for the 

 adults to oviposit, varied from 20 to 3G days. The data upon the 8 

 individuals was obtained during September and October, and the life 

 cj'cle was undoubtedly longer at this time than in midsunnner. The 

 length of life of the adults observed on confined indixidual^- was 

 from 4 to 36 days. 



Xumher of hroods. — Although the number of generations in a sea- 

 son has not been definitely observed, there are probably four and a 

 partial fifth during the period of ^lay to July, inclusive, and one 

 generation in each of the months March, April, August. September, 

 and October, making in all a possibility of eight to ten generations 

 for the season. 



HABITS. 



Tlie orange thrips is very active, especially in the adult form. Its 

 ability to run. leap, and fly is much greater than that of any other 

 thrips so far observed by the writers. This activity and their 

 small size allow them easily to pass unobserved. The writers have 

 frequenth' seen adults fly from one tree to another 20 feet or more 

 distant. The}^ nndonbtedl}- move about to a certain extent, and will 

 go from one orchard to another in search of suitable food. Fre- 

 quently they will desert the orange groves, between periodical 

 growths, for grapes and certain deciduous fruits. 



The orange thrips appear to thrive best in sunny and even very 

 hot weather. On cool cloudy days the}^ are less active and generally 

 group themselves on the underside of the leaves. 



Their reproductive habits are only partially understood. Males 

 are present pa it of the year, but usually in more limited numbers 

 than the females. 



EXPERIMENTS WITH METHODS OF CONTROL. 



CULTIVATION. 



Attempts have been made to control the orange thrips, in part, by 

 means of cultivation, but none of these endeavor^ has been in the 

 least successful. One orchard was hand-raked under the trees and 

 the soil stirred up in the fall, with the hope that pup;e would be de- 

 stroyed, but results were negative. Another orchard which was 

 plowed deeply in the fall yielded similar results. 



