THl': PKAK THKIPS. 



the plant epidermis with the stylets, then, moving" the cone tip back- 

 ward and forward, it enlarges the opening and lacerates the plant 

 tissue by means of the barbed snout. Jt then pushes the tip of the 

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

 juices. Larvte feed in a similar way, liaving similarly constructed 

 mouth-parts. 



KKLATIOX OF THK HIDDIXG AND BLOSSOMING OF TREKS TO TIIK FEED- 

 ING HABITS OF TIIIUPS. 



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

 and early March, tho ])oriod of early opening buds and tlrst blossoms; 

 they are connnon in Mai'ch and April, the two months of l)looiii and 

 early leaf, and all are gone 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 this time 

 and have gone into the ground. Thus it is 

 that the active feeding stages of the thri]' 

 coincide with the budding, blooming, aiui 

 early leaf periods of the host trees. 



The difference in bud formation and pro- 

 gress oi development of various deciduous 

 trees influence to a large extent the imxn- 

 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 hi which a single 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 ])roduces a cluster of 

 fruits, as the i)rune, cherry, pear, and apple. 



The relative bloomnig periods of the several varietits of fruit on 

 which thrips inflict injury, as found in tlu^ vSanta Clara A'alley, may 

 b(> nt)ted as follows: 



(Jnuip !: Aliuoiuls, laic in February; upricols and pcaclus, early in March. 

 Group 2: Pniiu's, middle and last of March; clierries and pears. < arly in Ai)ril. 



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

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

 suggestive. Opening buds precede full bloom by 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 February, early blossoms from February 5 to 16, and 

 full bloom from February 9 to 20 and later. Thrips ap])ear about 

 Fel)ruary 25 or March 1, and it is evident that almond blosst)ms are 



Fig. 1.— The pear thrips (A'a/Ar/p*- 

 pyri): headauJ prothoraxfrc m 

 .side, to show mouth -parts. 

 Mucli enlarged (original). 



