10 BULLETIN 616, TJ. S. DEPARTMENT OF AGRICULTURE. 
color natural to the ripe fruit are rare in that section, a blending or 
streaking of the natural red and the gray thrips injury being charac- 
teristic. The grape (PL III, fig. 3) ranks next to the pomegranate in 
degree of infestation. It is attacked mostly during the period be- 
tween growths of the orange. Both leaves and fruit suffer, but 
chiefly the fruit. In 1911, when citrus trees made but slow and scant 
growth, a case of severe injury to a small vineyard of Malaga grapes 
was reported to the writer. This vineyard was located among orange 
trees which had grown very little during the summer, and the thrips 
had concentrated there, scarring a large percentage of the berries and 
distorting many leaves. 
Apricots, peaches, plums, and pears are attacked more rarely ; rasp- 
berry, very rarely. A part of the scabbing found on the pear is 
probably due to other species of thrips, although new pear leaves 
occasionally have been found so badly curled by Scirtothrips citri 
that they looked diseased. 
The California pepper tree and the Chinese umbrella tree are both 
very attractive to the citrus thrips, which become abundant on them 
at certain times of the year. Neither of these trees show the effect 
of thrips injury from a distance, as do orange trees, and though ovi- 
position takes place in both varieties eggs are not deposited in 
umbrella-tree leaves in the fall. The insects do not attack the small, 
berry-like fruit of the pepper tree. 
The remaining food plants listed in Table I are attacked but rarely 
and some of them (almond, walnut, and tumbleweed) are probably 
only accidental food plants. More thrips have been found occa- 
sionally on the common dock than on any other of the noncultivated 
plants. 
LIFE HISTORY AND HABITS. 
THE EGG. 
DESCRIPTIVE. 
The egg (fig. 3), as seen in position through the translucent body 
wall of the parent thrips, is a bluish- white, bean-shaped object meas- 
uring on an average about 0.185 mm. in length by 0.085 mm. in width. 
It is comparatively very large, so that five eggs in an advanced stage 
of development occupying the ovaries at the same time cause consid- 
erable distention of the abdomen. 
When freed from the ovaries, immediately after deposition, the 
egg is thick at the base, with the upper two-thirds gradually drawn 
out into a narrower, necklike portion. The color is then clear ultra- 
marine and the surface is smooth and glistening. The membrane 
is flexible, so that the egg may assume other shapes within certain 
limits. As the embryo develops the bright-red eyes become visible 
through the transparent shell. 
