10 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
nymphs from the ground early in May, but it is difficult to explain 
their presence there so early in the spring. It hardly seems possible 
that these were the still immature forms of the previous year, for by 
this time all adult thrips had left the trees. These nymphs were 
taken along with the larve, which had just entered the ground, and 
| it might seem that they were hurrying through to produce a second 
1 generation; but to the writer’s certain knowledge adults of a second 
| generation did not appear on the trees. The nymph is active at all 
| times. Wings develop from mere buds to long sacs which project: 
backward along the sides of the body, and eventually reach beyond 
it the tip of the abdomen. 
THE ADULT. 
| 
} 
| 
| 
| The adult thrips (fig. 6) remain in the pupal chamber for days, 
and it may even be weeks before they issue forth to take up active 
|| life. How individual thrips force their 
| way through the several inches of earth 
. which lies above them is still a question. — 
| They come out, it 
| seems, only after 
the ground has — 
been thoroughly 
softened by 
rains, and it is 
evident, too, that 
they depend 
largely on the 
natural open- 
ings. They can 
not possibly use the backwardly bent mouth 
cone as a means of boring or biting their way _ 
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in forcing a way through the soft soil. Th 
also possess roughened, scoop-like structures— 
i : parts of the chitinous, hoof-like shell of the 
| Pape gecre saute wack feet—which undoubtedly are used for digging. 
eulateeaiceriginal). Adult thrips appeared in alarming numbers 
in many Santa Clara Valley orchards in 1904, about February 24; — 
in 1905 several days later, and in 1906 about March 1. They appear 
on the trees by millions and, it seems, all at about the same time. 
They feed and oviposit most actively during March and April, and 
by May 1 almost all have disappeared. No male individuals of the 
pear thrips have ever been collected; all have been females. a 
out. They have several groups of spines andy 
F| certain angular edges on the sides oi the ab-4 
| dominal segments, however, which might be used — 
