38 



BULLETIN 416^ U, S. DEPARTMENT OF AGEICULTURE. 



probable that the daily average of No, 2 (Table VII), which was over 

 35 eggs per day, represents the normal capacity of the species. 



Table VII. — Red spiders consumed by Scolothrips sexmaculatus, Batesburg, S^ C. 



Individ- 

 ual No. 



Feeding 



days. 



. Consumption. 



Eggs. 



Active 

 individ- 

 uals. 



Eggs and 

 active in- 

 dividuals. 



Average 

 per day. 



1 



1 

 2 



7 

 2 









9 i 4.5 



2 



1 

 2 

 3 

 4 

 15 



47 

 93 

 18 

 5 

 13 





























176 



35.4 



3 and 4 1 1 | 8 | 1 1 9 | 9. | 



5 1 1 1 35 





35 1 35.0 











6 1 i 4 1 4 8 j 8.0 



Total 6 



10 ! 232 



5 



237 



2 23.7 



1 This was first adult day. 



2 Average. 



Monlton, the first investigator to establish that thrips in general 

 are preyed upon by the insidious bug, states that Triphleps insidiosus 

 is the most serious enemy of thrips. Quaintance also states that 

 thrips, in addition* to being attacked by the insidious bug, are para- 

 sitized by nematode worms. At Batesburg we find that T. insidi- 

 osus is very often present with Scolothrips and other thrips, and that 

 it commonly feeds upon Scolothrips in the absence of more desirable 

 food. The time required by Triphleps adults to drain a thrips aver- 

 ages about 2h minutes. A half -grown chrysopid larva was observed 

 to grasp and drain a nymphal thrips in 1 minute 35 seconds, and 

 immediately seized other thrips, repeating the operation. 



Euthrips fuscus Hinds. — This thysanopteron, while frequently col- 

 lected in red-spider colonies, has not been observed in the act of 

 devouring red spiders; but our observations and those of other 

 workers indicate that this species is also an occasional enemy of the 

 mites. 



Euthrips occidentalis Perg. — This species has also been seen from 

 time to time in red-spider colonies. The evidence concerning it is 

 not absolute, but it is believed to be, like the two foregoing thrips, a 

 predatory species. 



HEMIPTERA. 



ANTHOCOErDAE. 



Triphleps insidiosus Say. — This predacious bug (fig. 10) seems to have 

 been first recorded as a natural enemy of the red spider by the senior 

 author in an earlier (1912) circular. Since then it has been recorded 

 as predatory on the co mm on red spider by Quayle (1913) and Ewing 



