LIBRARY

THYSANOPTERA 257
The blossom thrips, Thrips imaginis Bagnall, is a pale-yellow and brown
species that greatly resembles the tobacco thrips in color and size_ It is a native
of Australia which appears at times in immense numbers and flies in swarms
on hot days so as to "constitute a plague" and to become most annoying to man.
It infests a wide variety of plants and has been specially injurious to the blossoms
of roses, apples, pears, berries, and other fruits in which the eggs are inserted.
It also attacks the stems of potatoes and other plants but is essentially
FIG. 88. The Greenhouse thrips, Heliothrips hlBmorrhoidalis (Bouche}, a widely distributed
tropical and subtropical species. (After Russell from Insects of Western North America.)
a blossom-infesting species. It has several generations a year. Pupation occurs
in the soil.
The greenhouse thrips, HeUothrips hremorrhoMalis (BoucM), is a darkbrown
species 1.0-1.2 mm. long with conspicuous reticulations on the body and
parts of the legs. It is probably a tropical and semitropical species which lives
out of doors in warm and temperate regions and in greenhouses in less favorable
areas. It is almost cosmopolitan in distribution and is known to occur in
Europe, Asia, North America, the South Sea Islands, and Australia. Males are
unknown.
The corn thrips, Limothrips cerealium Haliday, is 1.2-1.4 mm. long, dark
brown to black, with pale markings and distinct surface reticulations. This is a