4 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
well along before enough thrips have appeared to become especially 
injurious. Many instances can be cited where thrips were especially 
numerous on almond trees, often as many as 25 or 50 inhabiting a 
single blossom, and yet the trees set and matured a full crop of nuts. 
The insects did not have an opportunity to attack the opening buds, 
and after blossoms were open they preferred the nectary glands on 
the inside of the calyx cups. They did not, apparently, relish any 
other parts of these particular blossoms, and the pistil, stigma, and 
young fruits were not attacked. Stamens were weakened, for they 
arise from the rim of the calyx just above the place where the insects 
find their enticing food, but the pollen had already ripened and had 
been shed. Thrips can be found as numerously on almonds as on any 
other variety of affected trees, but there is a large, newly exposed leaf 
and blossom surface, and the greatest danger period is passed before 
the insects arrive. For these reasons the trees are able to support 
many thrips without the amount or the quality of their fruit being 
appreciably affected. 
The peach, especially the Muir and the Nicols’ cling varieties, 
suffers as much as other fruits, but the acreage in the Santa Clara 
Valley is not large as compared with that of the prune, for instance; 
consequently the damage has not been so marked. The period of 
opening buds and blossoms occurs just at a time to permit of thrips 
entering them from their earliest development. The swelling bud 
pushes apart its outer winter protecting scales and thrips immediately 
force a way in. The insects feed on the tender, closely plaited tips 
of petals, which are readily killed. They force an entrance between 
calyx lobes and petals, feeding as they go, and soon reach and attack 
the very small and fragile blossom stem. This is soon destroyed. 
Later the blossoms which may have escaped the early injury are 
attacked from within, the thrips feeding on the inner flower parts. 
The piercing and rasping manner of feeding is very disastrous to ten- 
der plant tissue, and fatal injury can be effected by a very few move- 
ments of the powerful mouth cone with its armed tip. The writer 
has often examined peach trees which had but recently been attacked 
by thrips and found that almost every blossom would fall out from 
its cluster of scales when the limbs were gently tapped. Badly 
infested peach trees do not bloom at all. 
Apricot blossoms are similar to those of the peach and are injured 
in the same way. | 
The thrips is at its worst on trees of the second group, which 
includes the pear, prune, cherry, and apple. These fruits bloom 
later, which permits the gathering of thrips in numbers before 
buds are at all advanced. The writer has found thrips on cherry and 
prune trees waiting, as it were, for the buds to open, and he has found 
as many as 75 individuals in a single blossom which opened prema- 
turely early. A thrips enters a prune bud through the tip and forces — 
