330 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 7 



decimation of a more or less complete nature has occurred within the 

 ranks of the pest. During the seasons of 1911 and 1912 this mite 

 decimation occurred mainly in the last two weeks of xlugust. In the 

 case of the past season, the decimation occurred during the early 

 days of July, or nearly six weeks in advance of the case of the two 

 previous years. The phenomenon, indeed, happens suddenly, and 

 the agencies which work to produce it are unquestionably of great 

 economic importance. The ageing and toughening of the leaves at 

 about this time may cause some mites to desert cotton for other 

 plants, but the factor of real importance is the abundance of several 

 species of insect enemies which gain dominance at just this time. 

 Following are the beneficial species of particular economic importance 

 which have been observed at Batesburg during the last three seasons. 



Careful observations have convinced us that the larva of a small 

 Itonid fly occupies first rank among the enemies of the red spider. 

 The species — Arthrocnodax Carolina — was very recentty described by 

 Doctor Felt from material sent to himirom Batesburg. This predator 

 appears to confine its attack entirely to the eggs of the red spider. It 

 usually becomes noticeable first about the middle of June and multipUes 

 rapidly until toward the end of July, when the species becomes so 

 superabundant that its checking effect on red spider infestation is 

 most conspicuous. Too much emphasis cannot be placed on the 

 economic value of this species, and to its activitiy is probably largely 

 due the seasonal decimation of the red spider. It has been collected 

 from Virginia, North Carolina, South Carolina, Georgia, Florida and 

 Alabama and has, evidently, a wide distribution. It is interesting 

 to note that this predator becomes heavily parasitized later in the 

 season by a minute Chalcidid fly which has been identified by Crawford 

 as A'phanogmus floridanus. 



The insidious bug, Triphleps insidiosus, of the family Anthocoridoe, 

 probably ranks second to Arthrocnodax as a predator upon the cotton 

 mite. It appears somewhat earlier in the season than the latter, being 

 seen occasionally as early as the middle of May. Both the nymph and 

 the adult stages prey upon the red spider, the former feeding chiefly 

 upon the mite eggs, while the latter attacks adults and immature 

 stages. 



The small, dark Coccinellid species — Stethorus punctum — was very 

 abundant through July, and in the case of some badly mite-infested 

 jump-vine leaves, it was responsible, almost unassisted, for the exter- 

 mination of the pest. This species ranks close to Triphleps as a mite 

 predator. 



A species of lace-winged fly, Chrysopa ocrdata, probably ranks next 

 in order among the enemies of the red spider. They become plentiful, 



