THE RED SPIDER ON COTTON. 5] 
TABLE XX.—Consumption of red-spider eggs | by Arthrocnodaz carolina, Batesburg, S. C. 
Collected. _ Feeding. z a 4 gS 
3 : : : a reine 5 ian 
n 1 1 AX BS LS a on 6 
nae 38 o8 38 oc 38 se Oe 3 on 
; Date. Condition. Silos boo (Se) oo |. 8 | ao = oa. 
7 SIMS dey 5 Sis ligssis a 558 
A Sia | Ss on | AE o) ° =} >and 
Esa (RAL tet tall wall healt ll daalitea film = a, a 
(i Soe Aug. 29,1914 | Halfgrown...| 91 OONIEUROS At Mv eitie ee 75 3 -Septy. a 25 
By ath. Sept. 7,1914 | Small......... 136s |e 10M Stee) er ay Be nie 155 2| Sept. 9 77.5 
3) te ae loses doteee fs |-2 22-00. coeeee 35 Son seas eae SS Ee yd 73 2 doze 36.5 
OS eepe es Sept...8,1914 | Veryminute..| 53} 30 LOE Sa AA ia 95 3 | Sept. 11 S17 
Pe a Sept. 10,1914 | Large......... AD a een Ave Ree atl a 42 1 do.. 49 
Gee. Sept. 11,1914 |..... GO ee OSM et 4 mal: eee Mach Aig, 58 1 | Sept. 12 58 
7, ie Sept. 13,1914 | Two - thirds| 67 |...... Lees fer eae | a 67 1 | Sept. 14 67 
: grown. | | 
aha Sept. 26,1914 | Small......... 53 SOW OD Muar ate ewan 113 3 | Sept. 29 OY) 
1) oa ea do. _/:2-<-) Rather large. .| 51 AS Neat Nig TRB 3 94 2 | Sept. 28 47 
Cee Oct. 27,1914 | Nascent (?)...| 81 80) 43 400i) (891) 283 5 | Nov. 1 56.6 
Motaleawec ese un hee sak | Pace 1,055 | 23 | Liner awe 45.9 
1 Jn addition to eggs, some immature mites were also eaten and they are included inthe daily con- 
sumption figures. 
In the foregoing tests 10 larve ate 1,055 eggs in 23 feeding days, 
which vields 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 eges 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 larve 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 larve devour an egg in from 
1 to 2 minutes, while the smaller larvz require more time according 
to their size. 
Arthrocnodax carolina is parasitized by the minute chalcidid fly 
Aphanogmus floridanus Ashm. 
Mycodiplosis macgregori Felt.—During the season 1914 we have also 
detected a second itonidid species which is predacious upon the red 
spider. The larva of Mycodiplosis 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 Arthrocnodax, being occasionally found at Batesburg as late as 
early December. No special experiments have been undertaken to 
