>5 THE BEAN THRIPS. 
In the Imperial Valley the life history of the bean thrips and its 
injuries to alfalfa and cotton have been investigated by Mr. V. L. 
TTildermuth, of this bureau, and where his observations are used 
credit is given in the text. 1 Use has been made of observations, 
by Messrs. P. E. Jones and S. TV. Foster, of this bureau, on this insect 
in the more northern points in the State. Since July. 1911. the writer 
has been ably assisted by Mr. John E. Graf. He also wishes to ex- 
press his appreciation to Dr. F. II. Chittenden, under whose direc- 
tions he has conducted the investigation, and to Prof. F. M. AYebster 
for the free use of notes obtained by his agents. 
NATURE AND EXTENT OF INJURY. 
The damage caused by the bean thrips is not confined to the foliage, 
but affects as well the fruit and stems of the plant attacked. The 
injury is caused by the method of feeding. 
Both young and adults obtain their food by 
puncturing the leaf tissue with their sharp 
mouthparts and. after lacerating it, with- 
drawing the plant juices at the point of 
attack. Figure 1. although a drawing of a 
different species, gives an idea of the mouth- 
parts of this insect. 
Each time as the contents of the leaf at 
the point attacked are removed, the thrips 
moves to a new point and repeats the opera- 
tion, so that if the insects are abundant or 
the attack is long continued the leaf tissue is 
Fl head'7f Sl a ae tiir^ showing destroyed over the entire surface. As the 
the mouthparts. Much eu- supply on one side of the leaf is exhausted 
larged. (After Moulton.) V i . ,-, ,i -ft 
the larvae move around to the other, or it 
adults are present these fly or jump to more tender leaves. The 
infested and badly injured leaves turn yellowish or white, dry up, 
and either drop off or hang lifeless to the plant. Then, as the 
attack continues, successive leaves are attacked until in extreme 
cases the entire plant is killed. 
DESCRIPTION. 
Heliothrips fasciatus belongs to the Suborder Terebrantia and the 
Family Thripidae of the Order Thysanoptera. being placed in this 
position because- of the downward-curved ovipositor of the female. 
The 8-segmented antenna?, with the last segment much longer than 
the 7th, and the reticulated surface of the body, together with the 
pointed spines on the wings, place this insect in the Genus Helio- 
iMr. Wildermuth studied the insect in its relation to alfalfa, without knowing that it 
was being investigated by the author. His studies, made under quite different climatic 
conditions, add materially to the value of the results obtained. 
