42 
THE BEAN THEIPS. 
the bean thrips, and in confinement larvae were observed to kill and 
eat large numbers of the host. 
The young of Triphleps insidiosus Say were noticed on many 
occasions feeding on the young of this thrips and undoubtedly aid 
in reducing its numbers. 
The larvae and adults of Hippodamia convergent Guer were fre- 
quently collected on plants infested with thrips, where they were 
busily engaged in feasting on the tender larvae of the bean thrips. 
On several occasions larvae of a preclaceous thrips, probably sEolo- 
thrips fasciatus L., when collected were feeding on the larvae of the 
bean thrips. 
Fig. 
11. — A hyruenopterous parasite, Tliripoctenus russelli: Adult. 
(Author's illustration.) 
Greatly enlarged. 
Mr. P. K. Jones informed the writer that at Lindsay, Cal., in 
1910, he found a " nematode parasite working in the full-grown 
larvae of the bean thrips." 
A curious circumstance in connection with the observations made 
on the natural enemies of the bean thrips was the fact that in all of 
the preclaceous forms noted the alimentary tract became bright red, 
undoubtedly due to the crimson or reddish pigmentation of the host. 
ARTIFICIAL CONTROL. 
CULTURAL METHODS. 
In the case of crops planted over large areas and difficult or im- 
possible to spray, such as beans, alfalfa, or cotton, cultural methods 
offer the most hope as a remedy for the bean thrips. "Where this 
insect threatens injury it is recommended that these methods be used 
so far as possible. It is very important that the crops be given 
