'>50 Repoim' of 'iiii'; Dki'akt.mk.nt ov Kx'idmoi.oc'i of thk 



is unaffected. These Avouiided areas later form holes and the 

 leaves become much perforated and quite ragged in appearance. 

 The larvse attack plum leaves and fruit in a similar manner. 

 After feeding for about two weeks the larvae begin to drop from 

 the foliage, when they may be found on weeds beneath the trees. 

 From these they obtain subsistence for a short period when they 

 enter the ground and form resting cells in which to complete their 

 transformations, — in the autumn to pupiB, and later in the season 

 to adults. 



Seasonal hisforij. — Tn the spring the adults emerge from the 

 ground and seek the trees which afford attractive conditions for 

 subsistence and the deposition of eggs. Selecting the buds that 

 are beginning to open at the tips, the winged thrips work their 

 way within and attack the tender flower and leaf parts. The date 

 when the mature insects first ai:)peared on the trees this spring was 

 not obtained, but a few specimens were observed on April 26. 

 They seemed to be most numerous and destructive from April 28 

 through the first week in May. With the falling of the petals 

 from May 11 to May 14 the adults became less numerous on pear 

 trees, and practically disappeared from plantings of this fruit by 

 the latter part of the month. Oviposition was most active during, 

 the last few days of April and up to the middle of IMay. The 

 first young thrips was detected on May 9, and on succeeding days 

 larvsp emerged in large numbers, being very conspicuous in the 

 calyx basins of the fruit following blossoming. The latest date of 

 emergence of larvse was May 25. The young thrips commenced 

 to drop to the gi'ound beneath the trees on May 17, when several 

 of them were caught on sheets of sticky fly-paper. Plants under 

 the trees were then examined and many larva? were found on 

 leaves of burdock, bitter-sweet, chick-weed, dandelion and wild 

 rose. Quite a few individuals were entrapped in spider webs. 

 Siftings of the earth during the summer and fall revealed no 

 changes in the conditions of the larvae imtil October 13, when the 

 first pupa was found. The first adult to be found in an earthen 

 cell was obtained on November 29. 



