October, '21] weldox: thrips injuring peach 427 



skin of the nectarine. Wav}- red lines are commonly seen on such vari- 

 eties as Lovell, while russet or scabby patches and streaks may be found 

 on practically all varieties where injury has taken place. 



This injur}^ while as has already been stated, does not seriously impair 

 the qualit}' of the peach, makes it very difficult to remove the peel when 

 the fruit is being canned. In the modem commercial canneries the 

 peaches are peeled by means of lye and it was found that the lye bath 

 did not successfully remove the skin from thrips injured peaches, thus 

 necessitating hand trimming of the portions of the fruit affected, which 

 is slow and expensive. 



Other Hosts 



Not only is the species of thrips which is found injuring peaches injur- 

 ious to .this fruit, but it is also ver^^ commonly found on pliims, apricots 

 and nectarines. In the case of the nectarine the injury is more severe 

 than \vith any other fruit where the pest has been seen. Plums are 

 frequently badly injured while apricots are injured to a lesser extent. 

 The Royal variety which is more commonly grown in California than 

 any other variety of apricot, does not seem to be so susceptible to attack 

 as the Tilton variety, another commercial sort which is commonly grown. 

 Wherever the latter variety has been obser\^ed, large nimibers of thrips. 

 have been found feeding upon it. 



A species that may be identical with the peach species has been found 

 feeding on apples in the Yucaipa section of San Bernardino County. 

 During the season of 1920 there were large numbers of thrips in the 

 blossoms of the apple but the injury did not seem to be great. 



Seasonal Occurrences 



Forttmately the thrips pest seems to vary greatly in its attack from 

 season to season. As has already been stated during the season of 1919 

 and 1920 the injury in the Ontario-Cucamonga-Pomona section of South- 

 em California, was ver>^ severe. This year, 1921, the injury was slight 

 and in the spring it was rather difficult to find orchards where there were 

 enough thrips to make experimental work worth while. Then too, the 

 blooming season of peaches in 1921 extended over a much shorter period 

 than the previous season. This factor in itself bears a veT\r close relation 

 to the damage done by the insect for when there is a long blooming 

 period there is a correspondingly long time for the insects tofeed in the 

 blossom a nd under the husks which of course, means far greater injury. 

 While the blooming season in 1920 as has been stated, was from two to 

 three months, in 1921 peaches were through blooming in practically 

 one month's time. 



