12 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
METHODS AND NATURAL FACTORS IN CONTROL. 
The study of the life habits of the pear thrips, as already given in 
detail, explains why certain artificial remedies are not entirely effect- 
ive, and it also suggests other methods. Adults appear suddenly in 
late February and early March. They enter the opening buds and 
feed largely in protected places, and always on newly developing plant 
tissue. Destruction to buds can be accomplished in a very few days 
it may be in less than a week. The fully developed wings of the 
insect permit of active flight and widespread distribution. Ovipo- 
sition, extending through several weeks, permits of a widespread and 
a continuous feeding period for the new brood. Eggs are safely placed 
within the plant tissue. Larve feed largely in protected places while 
on the tree, and then seek shelter and spend many months in the 
ground. An individual of the species will spend about eleven months 
in the ground and one on the tree, although the whole period of infes- 
tation cf trees by adults and larve may be about three months. 
SPRAYS. 
Exposed thrips, both adults and larve, can be killed by several of 
the contact insecticides, but sprays have not proved successful, be- 
cause the spray mixture can not be forced into the very tender buds | 
and blossoms where the thrips are, without injuring the plants, and, — 
besides, all of the thrips can not be reached by a single spraying. It) 
was found in the limited experiments of 1905 that thrips could be | 
killed over any given area, but that within a few days the infestation | 
would be as bad as though no spraying had been done. This is — 
accounted for by the presence of those thrips which escaped the spray | 
and by the new individuals which had migrated into the orchard. 
It would be impossible for all persons to accomplish their spraying 
within the few days when the thrips are arriving on the trees. Larvae | 
are more easily killed than adult thrips, but as they feed largely within — 
the leaf clusters they, too, are protected. Spraying to kill larvee would — 
necessarily be done after the serious injury from adults had been | 
effected. It might be possible to obtain some results by applying a | 
poisonous spray, but the ever newly unfolding leaf surface, upon 
which the insects could feed and which would not be poisoned, would || 
render this kind of spray almost useless. 
CULTIVATION. 
There is some ground for believing, although the evidence is not | 
conclusive, that thorough cultivation will figure largely as a means of 
control for the pear thrips; but even here the treatment must cover 
areas of considerable extent. Thrips larve in the ground are mostly | 
within reach of the plow, being usually found within 5 inches of the - 
surface, although a few may go deeper. On uncultivated areas they , 
