. Bulletin of the Department of Agriculture. Agriculture; Agriculture. THE PEAR THRIPS IN CALIFORNIA. 15 gained entrance into the bud cluster early in the season, and were left unmolested, the entire cluster was sufficiently injured to prevent the appearance of a single blossom. In 1909 there was greater evapora- tion, comparatively little of the characteristic bleeding showed at the tips of the buds, and far less of the blue molds appeared in any place. Also the thrips came out of the ground more slowly than in 1910. The latter year thrips were held back to a slight extent by cold wet we
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. THE PEAR THRIPS IN CALIFORNIA. 15 gained entrance into the bud cluster early in the season, and were left unmolested, the entire cluster was sufficiently injured to prevent the appearance of a single blossom. In 1909 there was greater evapora- tion, comparatively little of the characteristic bleeding showed at the tips of the buds, and far less of the blue molds appeared in any place. Also the thrips came out of the ground more slowly than in 1910. The latter year thrips were held back to a slight extent by cold wet weather, but once the emergence from the ground commenced, thrips came very rapidly. Then, too, they were more numerous throughout the entire section in 1910 than they were the previous year. The serious nature of this insect can be understood when it is re- alized that in a badly infested pear orchard it is far more usual to find from 75 to 150 and often as high as 200 thrips to the cluster than only 10 to 15. Any spraying to be effec- tive must be done before these thrips have remained long, in numbers, inside the bud clusters. A delay of four or five days in spraying the badly infested orchards in the spring of 1910 meant the loss of the entire crop, and in many cases a delay of two to three days for the first application meant a loss of more than half the crop. In the ability completely to de- stroy the crop the adult is of more importance than the larva, and in many large orchards the destruction of the developing fruit buds by the adults has been so complete that by the time the trees would normally come into bloom there was left no possibility for a crop of fruit. The larva, together with the injury which has been caused by the deposition of the eggs by the adult, can lessen the prospects of a good crop of fruit after it has appar- ently set. To secure the best results it is always desirable first to apply efficient treatment against the adult hi order to reduce the early
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