2 HOW TO CONTKOL THE PEAE THKIPS. 



days all prospects for a crop of fruit — the control of this pest is a 

 matter of considerable difficulty. 



As the insect is each year extending its range of food plants, its 

 capabilities for dissemination are correspondingly increased. There 

 is no reason to believe that the insect will disappear in a few years, 

 but it should be regarded as a permanent pest and at once realized 

 that only the most careful attention each year to necessary control 

 measures will make it possible to continue the profitable culture of 

 deciduous fruit in infested orchards. 



Conservative estimates place the damage caused by the pear 

 thrips, in the Santa Clara Valley alone, during the years from 1904 

 to 1910 at nearly $2,000,000, while the loss for the entire State during 

 this period probably exceeds $3,500,000. It is safe to say that the 

 thrips in the absence of treatment would cause an average yearly 

 loss to the State of over $1,000,000. Also each additional year an 

 increase of several hundred thousand dollars is to be expected, due 

 to the increase of area infested and the greater losses in the areas 

 previously infested. 



CHARACTER OF INJURY. 



Injury to the various fruit trees by this species is caused by the 

 feeding of the adults on the developing buds and early blossoms; by 

 the deposition of eggs into the fruit stems, leaf stems, and newly 

 formed fruit, and by the feeding of the larvae in the blossoms and 

 on the young fruits and foliage. On pears the greater injury is pro- 

 duced by the adults, which often prevent the trees from blooming, 

 while on prunes and cherries the larvae frequently prevent a crop of 

 fruit from setting after the trees have come into full bloom. Also, 

 the deposition of eggs into the fruit stems of prunes and cherries so 

 weakens the stems that much of the young fruit falls. The feeding 

 injury is not produced by a biting or chewing process. By rasping the 

 tender surfaces in the developing fruit buds and the young fruits with 

 their hardened or chitinous mouthparts, the thrips rupture the skin, 

 causing an exudation of sap which is often followed by more or less 

 fermentation, especially before blooming. The feeding by larvae 

 on prunes after blooming causes the well-known thrips "scab," 

 while most of the scarred and misshapen pears are caused by the work 

 of the adults. 



LIFE HISTORY. 



Adults. — The adults (fig. 2) or winged form of the thrips first 

 appear on the trees about the middle of February and emergence 



