THE RED SPIDER 01:^ COTTON, 5 



winter (in tlie Southeast) and it is usually an easy matter to find red 

 spiders actively feeding on these leaves. Such occurrences give rise 

 to the opinion that much of the mfestation in rural localities arises 

 from the wild blackberry. 



Several early vernal plants or weeds (escapes) play an important 

 role m the seasonal development and spread of the red spider. The 

 more important of these are hedge nettle (Stachys arvensis), wild 

 geranium {Geranium carolinianum) , sow thistle (SoncJius asper), 

 evening primrose {Oenothera laciniata), smiflower {Helianthus annuus), 

 and vetch {Vicia sativa). During March and April these plants are 

 usually to be found m beds and borders in sheltered positions and the 

 seasonal development of the red spider progresses faster than else- 

 where, owmg to the higher temperatures which obtam in these loca- 

 tions. Such beds are prolific dispersion sources. 



Garden beans are also important hosts, and throughout Jmie, July, 

 and August are seldom free from mites, at times becoming so heavily 

 infested that their color turns yellow and many of the leaves fall. 

 They are thus a constant menace to surrounding crops. 



Tomato vines are known to afford an opportune shelter for mites, 

 and after the abundant appearance of enemies of the red spider, at 

 a time when other infested plants have become cleared of mites, 

 tomato leaves may usually be fomid to harbor large numbers. This 

 doubtless comes about through the fact that tomato vines xarely 

 support enemies of the red spider. Hence they serve to harbor the 

 mites during periods of heavy mortality until the time arrives when 

 the latter may spread with impmiity to other hosts. 



Since 1855, when Glover reported mjury to cotton by a red spider, 

 Prof. H. A. Morgan (1897), Mr. E. S. G. Titus (1905, a, h), and other 

 hivcstigators have published on the damage to cotton by this pest. 

 As indicating the very general occurrence of the mite on cotton, it 

 is of interest that in the course of visits to many points in sections 

 of every cotton State, the common red spider was found in every 

 single locality. The majority of these records on cotton concern 

 very light outbreaks. 



LIFE-HISTORY SUMMARY. 



The eggs of the red spider are deposited on the under surface of 

 leaves of a great variety of plants. The eggs hatch in a few days 

 and tlie 6-leggod larvae at once begin to feed by inserting their sharp 

 probosces into the tissue of the leaf. The larval activities are con- 

 fincf] to the immediate region of birth, and the larvae soon molt into 

 S-legged nymphs. Females recjuiro two nymplial stages before becom- 

 ing aflnlt, \v]\']\() males require only a single nymphal stage between the 

 hirva and the; a(hdt. Tl)(; f(;nial(; protonympli., Uko the larva, after 

 a period about equal to tluit rcHjuired by the latter, molts to the sec- 



