THE PEAR THRIPS IN CALIFORNIA. 35 



able place for ovipositing will feed from 1 5 to 20 days before placing 

 any eggs, while individuals which emerge at a later dale, as, for in- 

 stance, from March 5 to 20, do not as a rule feed more than one or 

 two days before depositing eggs. Individuals which were taken from 

 emergence cages and placed in mica chimneys were observed ovi- 

 positing the day following their emergence. It is possible that in 

 the field thrips begin depositing eggs more quickly on certain varie- 

 ties of fruits than on others. This would be governed very largely 

 by the presence or absence of available tissue suitable for oviposition. 

 For this reason on the early blooming varieties of cherries thrips prob- 

 ably feed for a shorter time before oviposition commences than is the 

 case with other fruits. 



PERIOD OP EGG LAYING FOR INDIVIDUALS. 



The egg-laying period for individuals does not usually last for 

 more than three weeks. Individual thrips confined in mica chimneys 

 on March 5, 1910, did not deposit any eggs after the latter part of 

 March. The full period of egg laying for the entire brood throughout 

 all the infested areas extends from about February 20 until near 

 April 10, or a period of six to seven weeks. 



LENGTH OF LIFE OF ADULTS. 



Adult thrips confined in vials without food lived on an average 

 three days, while those confined in vials with food lived about two 

 weeks. Adult thrips confined on the trees within mica chimneys 

 lived from three weeks to one month. The length of life of individuals 

 in the field has not been observed accurately, but probably ranges in 

 duration from three weeks to one month and a half. 



RELATION OF EMERGENCE TO BLOSSOMING OF TREES. 



The emergence period extends from early February to early April 

 and is closely associated with the blossoming periods for the different 

 varieties of fruits. Budding and blossoming of the different fruits 

 is as follows: Almond buds begin to swell during the latter part of 

 January and early February, and this variety of fruit is in full bloom 

 between February 8 and 24. Apricots show first blossoms from Feb- 

 ruary 12 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 from March 8 to March 17. Black Tar- 

 tarian cherries reach full bloom by March 15 to 20, while the Royal 

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

 buds are beginning to swell between March 8 and 11 and first blos- 

 soms appear by March 20. They are usually in full bloom between 



