THE PEAR THRIPS. 3 
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. It then pushes the tip of the 
mouth cone into the puncture thus made and sucks in the plant 
juices. Larve feed in a similar way, having similarly constructed 
mouth-parts. 
RELATION OF THE BUDDING AND BLOSSOMING OF TREES TO THE FEED- 
ING HABITS OF THRIPS. 
The dark-brown adult thrips arrive on the trees in late February 
and early March, the period of early opening buds and first blossoms; 
they are common in March and April, the two months of bloom 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 
larve have reached full growth, by this time 
and have gone into the ground. Thus it is 
that the active feeding stages of the thrips 
coincide with the budding, blooming, and 
early leaf periods of the host trees. 
The difference in bud formation and pro- 
gress of development of various deciduous 
trees influence 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, ee ee sea kc 
namely: (1) Those in which asingle fruit bud _ side, to show mouth-parts. 
produces one blossom, such as the almond, “°° °™2rFed (original). 
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 apple. 
The relative blooming periods of the several varieties of fruit on 
which thrips inflict injury, as found in the Santa Clara Valley, may 
be noted as follows: 
Group 1: Almonds, late in February; apricots and peaches, early in March. 
Group 2: Prunes, middle and last 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 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 appear about 
February 25 or March 1, and it is evident that almond blossoms are 
