. 
ovipositor can be inserted through the 
THE PEAR THRIPS. 7 
ing eggs on such plants. The insect has proved itself a strictly fruit- 
tree pest, and it is carried to weeds and lives on them or on other 
plants only by accident. 
LIFE HISTORY AND HABITS. 
THE EGG, THE OVIPOSITOR, AND OVIPOSITION. 
The thrips egg is bean-shaped (fig. 2), light-colored, almost trans- 
parent, and is very large in proportion to the size of the abdomen 
when seen within the body of the adult female. Itis about 0.33 mm. 
long by actual measurement. 
The ovipositor (fig. 3) is made up of four distinct plates. Each 
plate is pointed, has a serrate outer edge, and is operated by powerful 
muscles and plates within the abdomen. The pairs on each side fit 
together along the inner edges with a tongue-and-groove-like structure, 
which in action renders possible a sliding back and forth, or sawing 
motion. The ovipositor is protected 
within a sheath in the ventral tip of 
the abdomen when not used, but before 
and during ovipositing it is lowered 
until almost at right angles to the 
body. 
Oviposition accompanies feeding. It 
seems necessary, indeed, that before the 
plant epidermis the thrips must first ip 
weaken or break an opening through Fic. 3.—The pear thrips (Euthrips pyri): 
this tissue with the mouth-parts. The ovipositor and end of abdomen from 
‘ 5 side. Much enlarged (original). 
successive operations of lacerating the 
plant tissue, lowering the ovipositor, placing an egg, and withdrawing 
the ovipositor require from four to ten minutes, and may be briefly 
described as follows: After making an incision with the mouth parts 
the insect moves forward, lowers and inserts the ovipositor, and by 
operating the tiny saws she makes a deep incision in the plant tissue. 
While the ovipositor is still deeply set in the plant, an ege is con- 
ducted through the cavity between the plates and deposited under- 
neath the epidermis. The ovipositor is withdrawn and the egg is 
thus left deeply embedded within the plant. During the oviposition 
period one often finds a branch or a tree, or even many trees, on 
which almost all thrips are ovipositing at the same time. 
The small, fragile, just-exposed blossoms, stems, and leaf petioles, 
and later the midribs and veins on the back side of the leaves, and 
still later even the leaf tissue itself, are the places preferred for ovi- 
positing. A thrips always places her eggs in the tenderest of the 
plant’s tissue. There is danger of the ovipositor getting caught if the 
tissue is hard. Also, it is necessary during ege development that the 
