38 BULLETIN 173, U. S. DEPARTMENT OE AGRICULTURE. 



orchard in which all fruit buds have been destroyed is poor feed- 

 ing ground for both adults and larvae and reproduction is at the 

 minimum under such conditions. This reappearance in damaging 

 numbers the third year makes it evident that the orchardists should 

 not allow their orchards to go untreated. It should be noted that the 

 years 1907 and 1910 were the only seasons in which the pear thrips 

 migrated to any great extent. No migration was known in the 

 season of 1911, although it was watched for. 



MANNER OF REACHING TREE TOPS FROM GROUND. 



Most of the adults when emerging probably crawl around for a 

 while on the ground until their wings get sufficiently dry and then 

 fly up into the tree. Some, however, must undoubtedly crawl up the 

 trunk, as a few have been caught by tanglefoot bands. This, however, 

 can not be used as a method of control, since very few go up this way; 

 moreover, the thrips would not be caught unless the bands were 

 renewed every day or so, because the bands do not remain sufficiently 

 sticky after a short exposure to the atmosphere. 



REPRODUCTION. 



According to Bagnall x an example of the male pear thrips was found 

 by him among some specimens of this species taken from plum 

 blossoms at Evesham, England, and submitted to him by Mr. Col- 

 linge, director of the Cooper Research Laboratory at Berkhamstead. 

 His only description is that "It is much smaller than the female and 

 the wings considerably overreach the tip of the abdomen." This is 

 the first report of the existence of the male of this species, and 

 in California very extensive observations by the writers and other 

 workers have failed to show a single male, and the only type of 

 reproduction known is by parthenogenesis. In all of the life-history 

 experiments to secure data upon the length of the egg stage indi- 

 vidual females were taken directly from the emergence cages and 

 isolated. It is highly probable that practically all of the eggs 

 which are deposited hatch, as no sterile eggs have ever been found. 



OVIPOSITION. 



Moulton 2 states that he has observed the adult in ovipositing 

 to make first a hole in the epidermis of the plant tissue with the 

 mouth before depositing the egg. Repeated observations by the 

 writers of a large series of adults during oviposition have failed to 



1 Bagnall, Richard S. A contribution to our knowledge of the British Thysanoptera (Terebrantia), with 

 notes on injurious species. In Jour. Econ. Biol., v. 4, no. 2, p. 33-41, July 7, 1909. See p. 39. 



2 Moulton, Dudley. The Pear Thrips (Euthrips pyri Daniel). U. S. Dept. Agr., Bur. Ent., Bui. 68, 

 pt. 1, rev., p. 7, Sept. 20, 1909. 



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