TH YSA NOP TERA 345 



The onion thrips, Thrips tahdci. — This is a serious pest of the onion. 

 It is found on the bulbs in loose soil and at the axils of leaves, causing 

 the disease known as white blast on account of the whitish appearance 

 of the infested fields. Although called the onion thrips, it infests a 

 great variety of plants. 



The greenhouse thrips, Heliothrips hcBmorrhoidalis . — This is a 

 tropical insect, which is often a serious pest in greenhouses; it is also 

 found out of doors in the milder California climate. Drops of a 

 reddish fluid which turns black cover the infested leaves. 



The bean thrips, Heliothrips fascidtus. — This is a serious pest on 

 oranges, alfalfa, pear trees, and various garden crops in California. 



The orange thrips, Euthrips citri. — This is a serious orange pest in 

 California and Arizona ; it deforms the new growth of foliage and causes 

 scabbing and scarring of the fruits. 



The pear thrips, Euthrips pyri. — This thrips infests pears, prunes, 

 peaches, and other deciduous fruits, both in California and in the 

 East. It infests the opening buds and blossoms, stunting the leaves 

 and blasting the blossoms. 



The tobacco thrips, Euthrips fuscus. — This is a destructive enemy 

 of shade-grown tobacco causing the injury known as white vein. 

 The white veins of the leaves show in the wrapper when manufactured 

 into cigars. 



The strawberry thrips, Euthrips trttici. — This species was first 

 described as a pest of wheat, hence its specific name; but on account 

 of its extensive injury to the flowers of strawberry it is now known as 

 the strawberry thrips. It is found in the flowers of almost all wild 

 and cultivated plants and is the commonest and most widely distribut- 

 ed of all American species of thrips. 



The grass thrips, Andphothrips stridtus. — This species infests June 

 grass, timothy, and other grasses by destroying the heads of the 

 infested plants. The young insect pierces the stem just above the 

 upper node, where it is tender, causing it to shrivel and all the parts 

 above the injury to die. The dead and yellow heads of grasses thus 

 destroyed can be seen in early summer everywhere in grass-growing 

 regions. This disease is known as silver-top. 



Control. — Thrips are destro3^ed in those cases where it is prac- 

 ticable to spray the infested plants by the use of contact poisons, such 

 as nicotine or kerosene emulsion, and soap solution. Detailed di- 

 rections for making and applying these sprays are given in many 

 published bulletins and in special text-books. The burning of old 

 grass in early spring would probably destroy the hibernating grass 

 thrips. . 



Suborder TUBULIFERA* 



In this suborder the female is without a saw-like ovipositor and 

 the terminal abdominal segment is tubular in both sexes. The wings 

 are iisualh^ present ; the fore pair only with a single vestigial, longi- 



*Tubulifera: tubulus, a little tube; fero, to bear. 



