54 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 



stems immediately after the winter protecting scales are opened. 

 This group, comprising the almond, apricot, and peach, in which each 

 bud produces but a single blossom, is noticeably less seriously affected 

 by thrips than the group which includes the pear, prune, and cherry, 

 where each bud opens to form a cluster of blossoms. The thrips are 

 admitted into the buds of the latter group immediately upon the 

 spreading of the winter scales and they feed on the outside of the 

 tender blossoms, so that these are weakened before they have a 

 chance to bloom. 



Thrips in feeding do not bite off and take internally particles of 

 the outer plant tissue, but tear open the outer layers of plant tissue 

 and, inserting the tips of their mouth-cones, suck up the juices of the 

 plant. This manner of feeding may penetrate through the very 

 young, tender leaves so that later, when the injured parts fall away, 

 the leaves become ragged and full of holes. On very young fruits 

 this feeding injury penetrates through the epidermal layers into 

 the flesh and forms a scab, but on more mature leaves and fruits, 

 where the outer tissues are strong and thick, the effect is that of 

 " silvering." 



The relative periods of the spreading of buds and blossoming of 

 the several varieties of fruits are important factors as related to the 

 injury which they receive by adult thrips. Of cherry, the follow- 

 ing varieties spread their buds and blossoms in the order named: 

 Republican, Black Bigerreau, Black Tartarian, Royal Ann, and 

 Bingo ; and of plum, Japanese plum, and Imperial, Sugar, and French 

 prunes. Such trees as almonds, which blossom very early, or as the 

 Royal Ann cherry, which blossoms late, are not as a rule seriously 

 affected. 



The budding and blossoming of fruits in the San Jose district is as 

 follows : Almond buds begin to swell during the latter part of Janu- 

 ary and early February, and this variety of fruit is in full bloom be- 

 tween February 8 and 24. Apricots show first blossoms from Febru- 

 ary 19 to 23, and most varieties are in full bloom by from March 3 to 

 10. Peaches show first blossoms about February 23, and many 

 varieties are in full bloom by from February 8 to March 17. Black 

 Tartarian cherries reach full bloom by March 20, while the Royal Ann 

 variety has not at that time opened its buds. French prune buds 

 are beginning to swell between March 8 and 11 and first blossoms 

 appear by March 20. They are in full bloom from March 26 to April 8. 

 The Sugar and Imperial varieties precede the French by about 

 one week. Bartlett pears begin to open their clusters from about 

 March 12 to 15 and are in full bloom for quite an indefinite period 

 from March 20 to April 10. Pears, prunes, and cherries which are 

 spreading their buds just after the maximum number of thrips are 

 coming from the ground, are the varieties most subject to injury. 



