THE RED SPIDER ON COTTON, 5S 
demonstrations of the economic value of the species have been seen 
in the field that it holds a position of greatest importance as an 
enemy of the red spider. Duffey records chrysopid larvee as pre- 
dacious on the pupe of this form, and we also have observed lace- 
wing-fly larvee devouring the immature stages. 
Stethorus utilis Horn.—This little brownish species has been ob- 
served in red-spider colonies on cotton. It is second in importance 
only to the preceding ladybird, and is most in evidence during July 
and August. An individual of this species (in the third instar) was 
observed to eat 3 mite eggs in 7, 73, and 8 seconds. This is the 
fastest rate of egg dpstruction noted for any predator. Another 
individual (in the fourth instar) sucked 4 mite eggs in 28, 72, 46, and 
77 seconds. Two larve were isolated and kept sped etn red 
spider eggs. One escaped, but the other was reared through to 
adult. Table XXII gives the life-history record of this indiidaal 
TABLE X XII.—Life cycle of Stethorus utilis, Batesburg, S.C. (Individual No. 1.) 
Hees collectede se eins 50.8 2. dralyy25.:| Meneth of incubation. 22.3. . 4 days (?) 
Hees natched spe e i eyee aly. 29), eleenethvoiiirst instars oe Guar ol 3 days 
Rarsteimolt220e ae so Sean ties 29:4. mm)! Weneth of second instars. 23... . 1, days 
Second molt 7.75.4 Amo 2 alle 30 ae mii weneth ot third instar. 522) 0... 21 days 
‘TMoobege Uso We) Nia Se ees apes Sie ae Ane.4. 3ip.m.| Wenethroet fourth, instar. 272 : 43 days 
suai 22 0 cmap eo Ne O49 aac. a epalamertod’. 4. A eesei ce . 0 4 days 
Adultassued 4. <2. A Aug. 13, 9a. m. | Deposition to adult.........- 19 days (?) 
Since the conditions surrounding this individual were as nearly 
normal as possible, it is probable that the foregoing record represents 
fairly the life cycle of the species. 
Table XXIII contains statistics covermg the entire feeding 
capacity of one individual of this species from hatching until adult. 
Taste XXIII.—Consumption of red-spider eggs by Stethorus utilis. 
leat eliie cirbe eens oe ea July 29. | Eggs eaten—Continued. 
Eggs eaten: (Penthh) day, tae. 44s ote eee a 116 
JBTESSG Clea tee SS er Pe, a 10 rane 
Second Ha Sea Meee yn 14 ee a wae 
SU Oe Oh CIE i ecg 2 ae age aa (uleneedineg dave uc eae vilken se: 10 
Bounlidayen ete inet (ae. = 32 | Average daily consumption......... 385 
HE rap lanchayy se eee 2: 32 38 | Eggs eaten: 
SIEGE Nc .5A em a Ape Sel eeae 17 Dunne frst instars see ges 31 
Bevemunyd ay ss 662512 2 tS. 38 During second instar......-..-- By 
Big aye nese Behe Durime dt birdimstanis sass. 55 
INO T nN GIES tes 5 Oe el eee 40 During fourthanstar 2232) 22: 267 
1 Was found pupated on eleventh day. 
It will be seen that the above individual in 10 feeding days ate 385 
red-spider eggs, or 38.5 eggs per day. Although this coccinellid has 
frequently been seen eating mites in outdoor locations, the experi- 
mental individual was confined to an exclusive egg diet, in order to 
