THE PEAK THKII'S. 



the plant opidormis with the stylets, then, movino; the cone tip hack- 

 ward and foiw urd, it enlar<:;es the <)penin<2: Jmd lacerates the plant 

 tissue hy means of the barhed sn<Hit. It then pushes the tip of the 

 month cone into the puncture thus made and sucks in the plant 

 juices, l.arva^ feed in a similar way, having similarly constructed 

 mouth-])ai'ls. 



RELATION OK TMK IJUDDINO AND lU-OSSOMINfJ OF TREES I'O THK FKHD- 

 INCi HAliirS OF IIIKIPS. 



The dark-brown adult thrips arrive^ on the trees in late February 

 and early March, tiie period of early opening buds and iirst blossoms; 

 they are common in March and April, the two montlis of bloom and 

 early leaf, and all are gonc^ from the trees 

 by the middle of May. Only a few adults 

 can be found after the 1st of May, and most 

 larva' have reached full growth by tiiis time 

 antl have gone into the ground. Thus it is 

 that the active feeding stages of the thri|)s 

 coincide with the budding, l)lo()ming, and 

 early leaf periods of the host trees. 



The difference in bud formation and pro- 

 gress of development of various deciduous 

 trees iniluence to a large extent the man- 

 ner of injury which thrips inflict. Trees may 

 be divided for the sake of convenience, in re- 

 gard to the bud structure, into two groups, 

 namely: (1) Those in which asingle fruit bud 

 produces one blossom, such as the almond, 

 apricot, and peach; and (2) those in which a single fruit bud opens 

 out to form a cluster of blossoms which later produces a cluster of 

 fruits, as the prune, cherry, pear, and a|>]ile. 



The relative blooming ])eriods of the several varieties of fruit on 

 which thrips inflict injur}^, as found in the Santa Clara Valley, may 

 be noted as follows: 



(iniii]) 1: Aliuonds, lat(> in Feljruary; aprirots and poaches, early in March. 

 (iriMip 2: rrnncs, middle and las), of March; cherries and pears, early in April. 



These periods vary from year to year and the varieties of each 

 fruit also vary to a large degree, but the general order of blooming is 

 suggestive. Opening buds ])recede full bloom ])y eight or ten days. 



The almond, of the first group, presents an interesting study of 

 the feeding habits of thrips. The bud development occurs dur- 

 ing early Kebruary, early blossoms from February 5 to 16, and 

 full l)loom from February 9 to 20 and later. Thrips appear about 

 February 25 or ^^arch 1 , and it is evident that almond blossoms are 



Fig. 1. — 'JMic ijcar tlirips (Juilhriii.i 

 l>liri): lu'iid ami iirolhoraxfniin 

 side, to show inoiilh-parts. 

 Much oiilarptMl (originiil). 



