26 BULLETIN 616, U. S. DEPARTMENT OF AGRICULTURE. 
trees. Adult thrips suffer from the lacewings only when the weather 
has become so cool as to make the thrips sluggish. 
In its early larval stage, the lady beetle (Hippodomia convergens 
Guer.) feeds upon the citrus thrips. Although this Coccinellid is 
extremely numerous throughout the Tulare County citrus belt, it 
feeds mostly upon aphids and other larger insects which occur on 
orange trees and more particularly on truck crops, and is of no 
great importance in destroying the thrips. 
A thysanopteron enemy of the citrus thrips which seemed to be 
increasingly important in 1912 was the 6-spotted thrips (Scolothrips 
sexmaculatus Perg.). The principal food of the 6-spotted thrips, 
however, appears to be mites which occur mainly on plants other than 
citrus in Tulare County and which are not numerous enough on 
orange to attract large numbers of the predatory thrips. This 
thrips is apparently just learning the possibilities of abundant food 
offered by the citrus thrips, and perhaps will feed more extensively 
upon it as time goes on. It is apparently unable to catch the adults 
and therefore feeds only upon the larvae. 
The younger nymphs of one of the assassin bugs (Zelus renardii 
Kolen) 1 are fairly common upon orange trees in Tulare County and 
have several times been seen feeding upon larvae of the citrus thrips. 
The more advanced assassin bugs, however, feed principally upon 
larger, and often harmless, insects and it is only in their first and 
early second instars that they attack thrips. 
The small reddish nymph of the plant bug (Triphleps insidiosus 
Say) has occasionally been seen feeding upon flower thrips in orange 
and several other blossoms. When imprisoned with Scirtothrips 
citri it flourished very well upon the latter, but when the flower 
thrips (FranMiniella tritici Fitch.) was also placed in the bottle the 
latter proved more attractive to the insect, doubtless because of its 
larger size and greater sluggishness of movement. Triphleps in- 
sidiosus has not been seen upon orange trees after the blossom period, 
when the flower thrips, upon which they mostly feed, have left the 
trees. 
INTERNAL PARASITES. 
Thus far no internal parasites have been found attacking the 
citrus thrips. Although the Chalcid parasite of Thysanoptera 
(Thripoctenus russelli Crawf.) 2 has been found by the writer in the 
San Joaquin Valley affecting the bean thrips (Heliothrips fasciatus 
Perg.) and the flower thrips (FranMiniella tritici Fitch.), for some 
1 Identified by Otto Heideman. 
2 This parasite was first reared from Heliothrips fasciatus Perg. by H. M. Russell (see 
U. S. Dept. Agr., Bur. Ent., Tech. Ser. Bui. 23, pt. 2, Apr. 27, 1912). It was described as 
a new genus and species by J. C. Crawford in 1911 (see Proc Ent. Soc. Wash., vol. 13, p. 
233, 1911). 
