THE SUGAR-BEET THRIPS. 3 
yellow calla (Richardea aethiojrica), tomato (Lycopersicum), and 
grape (Vitis). 
The writer has also found it on Begonia, spinach (Spinacia), sweet 
potato (Ipomoea batatas), string beans (Phaseolus), and Mexican tea 
(Chenopodium ambrosioides) . 
EXTENT AND NATURE OF INJURY. 
The injury caused by the sugar-beet thrips is similar to that of the 
other species of thrips of the group. The plant is attacked by the 
adult and nymphs in the same manner. The leaf cells are pierced, 
and the plant juices withdrawn, causing the cells to shrivel and turn 
white. When a number of these cells are destroyed they appear as 
irregular white or light-brown spots. If the attack is severe, the 
whole leaf surface becomes invested by these spots and finally shrivels 
and dries. The nymphs also render the plant unsightly through the 
brown watery excretion from the alimentary tract, which discolors 
the leaves. 
Plate I shows a leaf of Swiss chard attacked by this thrips. 
HABITS OF NYMPHS OF FIRST AND SECOND STAGES. 
When ready to emerge, the young nymph breaks through the thin 
eggshell and pushes its way upward until all but the last abdominal 
segment is free. It remains upright and supported by the last seg- 
ment until the appendages which are folded beneath the body unfold 
and become sufficiently hard for use. The forelegs are the first to 
unfold, followed by the middle and hind pair. The antennas are now 
brought forward. The nymph then places its legs on the surface of 
the leaf and by constant pulling frees the body. A period of from 
20 to 25 minutes is required for complete emergence. 
The newly-hatched nymphs crawl about for a short time before 
commencing to feed. They usually collect and feed in colonies on 
the underside of the leaf, but if food is not abundant, both sides are 
attacked. Shortly after feeding, the body becomes discolored by the 
ingested food. The watery excretion from the alimentary tract is 
collected as a globule, which extends over the entire body except the 
head, and increases in size until it becomes too large to carry, It 
is then dropped and spreads over the leaf, giving it an unsightly 
appearance. The older nymphs are very active and when disturbed 
move rapidly, with the tip of the abdomen extended upward. 
When full grown, the nymph seeks a secluded spot in which to 
transform. The curled portions of dead leaves form a favorite place 
of concealment, although the base of the plant and the portion of the 
leaves along the midribs may be selected.' 
