86 



Until within tiie year 1900 the common reel 8pider most of ten occur- 

 ring in gTeenhou.ses was technicall}" designated as TetranycJius telarms 

 Linn,, a name which has been rather indiscriminately applied to all 

 species of red spiders, both in America and abroad. 



Red spiders are not true insects, in fact not even spiders, but are, 

 more properly speaking, spinning mites. Since, however, they are 

 almost universally known as red spiders, this term is retained for 

 present purposes. 



As the word ''mite'' indicates, these insects arc extremely minute, 

 and Avhcn thc}^ occur in ordinai'v numbers are not apt to he noticed 

 unless leaves arc carefully scrutinized. Attention, however, is cei'tain 

 to be drawn to them when they become excessively numerous, as fre- 

 quently happens in neglected greenhouses 

 or out of doors during droughts in sum- 

 mer. 



Red spiders spin threads, l)ut do not, 

 like true spiders, utilize tliom for climl)- 

 ing or descending from a height. The 

 threads spun are extremely fine and 

 scarcely perceptihl(> to the unaided eye, 

 but a web of threads is frequently so dense 

 as to form a tissue plainly visible at a little 

 distance. AVebs are usuallv constructed 



Fig. 9. — Tdnin licit ati hiiiiacukitUK: 

 adult — enlari^ed (fnim Banks). 



Fk;. 10.— Telminj- 

 chus himaculatus: 

 palpus — enlarged 

 (from Banks). 



Yui.n.— Tdmny- 

 chua hiiniicula- 

 liis: claws — en- 

 larged (from 

 Banks). 



upon the lower sides of leaves, and attached here and there to project- 

 ing hairs, veins, or the edges of the leaves. AVithin the webs thus 

 formed the mites feed in their different stages, and the eggs are laid 

 from which the young develop. 



The general appearance of the red spider under consideration, which 

 is now known as Tetranyclms himaculatus Harv. as it looked under a 

 microscope, is well shown in figure 9. At figure 10 a greatly enlarged 

 palpus of the same sY)ecies is illustrated, and figure 11 shows the claws 

 similarl}^ enlarged. 



The length of full-grown individuals, inchiding the palpus, is from 

 0.4 to 0.6 """ and the width 0.2.5 to O.P>0 """, the thickness being 0.17 



