20 BULLETIN 616, U. S. DEPARTMENT OF AGRICULTURE. 
about an inch square and went through the following antics: Fre- 
quently it would elevate the abdomen, spreading the wings as in 
preparation for flight. Then it would crouch flat to the leaf, twisting 
the abdomen about with a rotary motion, at times leaning far over 
to one side and often moving backward, slowly turning about in a 
complete circle. At one time the insect turned completely over and 
lay on its back for a short space, the abdomen continuously moving 
as described. At the end of a half hour the ovipositor was slightly 
exserted from a point very near the tip of the abdomen, which was 
then arched and its tip brought into contact with the leaf surface. 
The ovipositor was then inserted in the leaf in a single movement 
from an almost vertical position to about two-thirds its length. The 
insect then relaxed slightly and remained quiet in this position for 
four minutes, when it moved away and rested. Only one egg was 
deposited. 
PORTION OF PLANT SELECTED FOB OYTPOSITION. 
The citrus thrips oviposits only in those tender tissues which are 
suitable for food. i. e., the new growth and the young fruit. Eggs 
are deposited largely in the leaves and fruit in summer and in the 
stems in fall, more particularly the large tender stems of the orange 
tree. In summer large numbers of eggs are thrust into the new leaves, 
leaf stems, fruit and fruit stems, and when the petals have fallen the 
fruit receptacles become a favorite place of oviposition, which is 
accomplished under the protection of the sepals. Eggs are never 
deposited in the blossoms. 
RELATION OF QUALITY AND AMOUNT OF FOOD TO OVIPOSITION. 
Eggs are never deposited in the older leaves and stems and but 
rarely in the fruit after it is two-thirds grown. The number of eggs 
deposited in a particular tree will depend exclusively upon the 
amount of new growth produced by that tree. It is impossible to 
induce the insects to oviposit in the tough leaves of potted orange 
trees, though hundreds have been confined upon such plants for many 
days. Eggs were deposited readily in the same kind of plants when 
one or more new leaves occurred there, even though only 20 to 25 
insects were confined through one night only. 
Oviposition does not occur in the minor food plants (including the 
Valencia orange, pomelo, lemon, pepper tree, Chinese umbrella tree, 
and grape), regardless of growth, in as great proportion to the 
number of infesting insects as in the Washington and Thompson's 
navel oranges. 
RATE OF OVIPOSITION AND NL'MBER OF EGGS DEPOSITED. 
The preoviposition period in midsummer, w^en metabolism is 
rapid, is three or four days. The highest average daily rate of egg 
