204 PESTS OF GARDEN AND FIELD CROPS 
The Onion Thrips (Thrips tabaci Lind.) 
A great variety of truck crops and some flowering plants under 
glass are subject to injury by this minute form of insect life. 
The juices are sucked from the leaves, causing numerous tiny 
white spots. The insect itself is so small 
as almost to escape notice. It is yellowish, 
slender, and one twenty-fifth of an inch long. 
Eggs are laid within the leaf tissue. Several 
generations may be developed in a season. 
Crop remnants and neighboring weeds should 
be burned in the fall. Attack may be checked 
by spraying with tobacco extract, being careful 
to get the material into the axils of leaves, 
since such places are favored by the pest. The 
insects are more active on the outer parts of 
the plant in the early morning, and thus are 
more easily reached at that time. 
The Tobacco Thrips ( Euthrips nicotiane Hinds) 
The work of this minute insect may be rec- 
. aa ognized by a whitening of the leaves, especially 
Fic. 253.—White spots along the veins. The adult winters in tobacco 
on onion leaf caused fields, and breeds rapidly in the warmer 
by the Onion Thrips. 
Enlarged to twice nat- : Mbiee 
ural size. Original. after they are gathered it lives on weeds, or 
often on oats. 
months. Before tobacco plants are up and 
Spray with kerosene emulsion, diluting the stock emulsion with 
10 parts of water. 
riata Osborn) 
The Grass Thrips (Anaphothrips s 
Usually the work of this insect is observed rather than the pest 
. ° ¥ . . > . 
itself. Various grasses, including oats, turn white, the appearance 
being known as “silver top.” More closely examined, the leaves will 
be found covered with white dots where the juices have been sucked out, 
