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to provision by Congress for an investigation of the insect by 

 the Bureau of Entomology of the U. S. Department of Agri- 

 culture, and Mr. Moulton, who in the meantime had been 

 employed by the bureau, was assigned to the work, beginning 

 July i, 1907, with headquarters at San Jose, Cal. 



The pear thrips attacks various deciduous fruits, as almond, 

 apricot, peach, prune, cherry, pear, apple, etc. The life history 

 is briefly as follows : Early in the spring, as in late February 

 or early March, the adult thrips begin to make their appearance 

 from the soil, at once attacking the opening buds or blossoms, 

 and by their feeding soon cause these to blight, literally nipping 

 the fruit crop in the bud. Oviposition occurs soon after emer- 

 gence, the eggs being placed in soft tissues, especially in fruit 

 and leaf stems or in the midribs. The young larvae feed upon 

 the tender tissues of the leaf or flower, requiring some three 

 or four weeks to reach their full size. They then leave the 

 plants and work their way below the soil from 3 to 4 or even 

 10 to 12 inches, depending upon whether this is hard or soft. 

 In the soil the thrips larvae construct small oblong cells where 

 they remain the balance of the season. In late fall and early 

 winter, transformation to the pupa stage occurs, from which 

 the adults develop to appear above ground about the time fruit 

 trees are beginning to bloom in the spring. There is thus but 

 one generation each year, and the insect spends practically ten 

 months in the ground. 



The pear thrips has proved to be a very difficult insect to 

 combat, and its practical control has not yet been determined. 

 The Bureau of Entomology is carrying out extensive experi- 

 ments and demonstrations in spraying in the infested territory 

 and is also testing over large areas the possibility of destroying 

 the larvae or pupae in the ground by cultivation or other 

 methods of soil treatment. Of many sprays tested, a pro- 

 prietary tobacco extract and a distillate emulsion have proved 

 most efficient. Spraying must be directed largely against the 

 larvae feeding on the more exposed portions of the plant. Of 

 the various fruits attacked, pears and prunes suffer most, 

 from the fact that the thrips are out in large numbers just 

 when the buds of these fruits are beginning to swell, and these 



