4 
THE RED SPIDER ON COTTON. i 
‘minimum, and he found that this fluctuation was induced largely by 
temperature and nutrition conditions. 
In the course of the five seasons’ observations at Batesburg many 
colonies have been reared under control. From a series of 90 such 
broods the summaries given in Table I are derived: 
TasBLE I.—Records of oviposition of the red spider. 
Meareest brood... .. 2. .2.4:-- SI AN PUES Sa oy Oe ea eniies POR agiSer ec ey ARSC ren 110 
Mere onedarestabtoods: - 2008 ees esa las 68. 01 
MerereonunlOareest broads). 4 420 Wk aaa ee 89. 10 
Metich daily depositions 12,1 13,? 14,3 15,4 16,> 17,* 19. 
Dermody ovlpostiion ook e sere RLU YT See ee 19 
Mn Mecaos rom GSMOTOOdsee OL. TL ok eee ee 1, 893 
Seeribesorlayinedayeios OFOOUS) oe a 320 
Berenaceierss perdayepertemale.c) ye i ee 5. 92 
Seaveracte ovipostime days pertemale !2 8. 222s leva... else 2. ol 14 
Beeman OViposmwime days per female. 23. 2. lee 36 
From these rearings it follows that for South Carolina the female 
under proper conditions will produce a brood of from 75 to 110, 
probably averaging about 85, and that the eggs are deposited usually 
in from 10 to 12 days at the rate of from 8 to 14 per day. ; 
Incubation period.—The duration of. the incubation period varies 
largely with the temperature in the different localities. Perkins 
(1897) found that 7 days were required in Vermont for this period, 
Ewing (1914) states that an average of 5.5 days were consumed at 
Corvallis, Oreg., between deposition and hatching. In Georgia from 
3 to 4 days were required for incubation, according to Worsham. In 
a series of 71 breeding-cell tests (each cell containing the progeny ° 
1 female) the average duration of this period at Batesburg was founc 
to be 3.93 days during May, June, July, August, and September. 
In hatching, the sheil splits more or less raul around and the 
larva easily extricates itself. Durimg severe occurrences of infestation 
the leaves of the host plant may be seen thickly covered with the 
bleached and empty eggshells, which disclose the cause of death of 
leaves long after the disappearance of the pest has occurred. 
The effect of temperature upon the incubation of the red-spider 
ege is very marked. In midsummer, at Batesbure, with mean daily 
Perperatntcs between 80° and 90° F., nbn rarely requires 
ue than 4 days. One rearing beginning March 12 consumed 15 
days for the hatching period. Eggs, in one case, deposifed November 
16 hatched in 23 days. During December, (Eee, and February 
egos may remain dormant for from 1 to 3 months, hatching with the 
advent of sufficiently mild weather. The relationship between mean 
temperatures and the length of the egg period is shown in Table 
If and figure 2. The eggs of a colony are usually clustered upon 
13 cases. 25 cases. 3 4 cases. 4 2 eases. 51 case. 
