Table XX. — Consumption of red-spider eggs ' by Arthrocnodax Carolina, Bateshurg, S. C 





Collected. 



Feeding. 



ft 



a . 

 s & 



p 0) 



a 

 o 



a 



«&■ 



1 



i 

 ft 



< t-, 



flft 

 o 



Larva 

 No. 



Date. 



Condition. 





O c3 

 ll 





o a 





O M 

 taoft^^ 



m r^ <^ 



1 



Aug. 29, 1914 

 Sept. 7,1914 

 do 



Half grown . . . 

 Small 



21 

 136 

 35 

 53 



42 

 58 

 67 



53 



29 

 19 

 38 

 30 



25 







75 

 155 

 73 

 95 

 42 

 58 

 67 



113 



94 

 283 



3 

 2 

 2 

 3 

 1 

 1 

 1 



3 



2 

 5 



Sept. 1 

 Sept. 9 



...do.... 

 Sept. 11 



...do 



Sept. 12 

 Sept. 14 



Sept. 29 

 Sept. 28 

 Nov. 1 



25 









77.5 



3 



do 









36.5 



4 



Sept. ..8, 1914 

 Sept. 10, 1914 

 Sept. 11,1914 

 Sept. 13, 1914 



Sept. 26,1914 



do 



Oct. 27,1914 



Very minute.. 



Lar.ge 



do 



Two - thirds 



grown. 

 Small 



12 







31.7 



5 







42 



6 











58 



7 











67 



8 



38 

 43 

 30 



22 







37.7 



9 . 



Rather large.. 

 Nascent (?)... 



Total 



51 



81 







47 



10 



43 



40 



89 



56.6 















1,055 



23 





45.9 





i 















I In addition to eggs, some immature mites were also eaten and they are included in the daily con- 

 sumption figures. 



In the foregoing tests 10 larvae ate 1,055 eggs in 23 feeding days, 

 which yields an average daily consumption of 45.9 eggs per day. The 

 largest number of eggs eaten in one day was 136. The fact that 

 this species often multiplies with great rapidity is explained in part 

 by the very short life cycle. Considering that each larva averages 

 46 mite eggs per day, and that as high as 52 midges have been 

 seen on a leaf, the remarkable control exerted by this midge may be 

 comprehended. 



This predacious species is seldom observed on cotton until infesta- 

 tion has assumed threatening proportions, and many mites in all 

 stages and innumerable eggs are present. As Quayle (1913) has 

 remarked, this species more often operates in colonies which are 

 covered with webbing, but whether this is instinctive or merely 

 incidental would be difficult to determine. The larvae are surpris- 

 ingly agile. Coming in contact with a mite egg, the head end is 

 instantly thrust against the shell, through which the piercing device 

 is forced and the feeding begins. Large larvae devour an egg in from 

 1 to 2 minutes, while the smaller larvae require more time according 

 to their size. 



Arthrocnodax Carolina is parasitized by the minute chalcidid fly 

 Aphanogrnus Jloridanus Ashm. 



Mycodiplosis inacgregori Felt. — During the season 1914 we have also 

 detected a second itonidid species which is predacious upon the red 

 spider. The larva of My(;odiplosis can not be distinguished in the 

 field from that of Arthrocnodax, and the habits and life histories are 

 doubtless much the same. This species is seemingly somewhat later 

 than Arthro(;nodax, being occasionally found at Batesburg as late as 

 early December. No special experiments have been undertaken to 



