TETRANYCHUS MOLESTISSIMUS 



355 



condition, measure O'i6 0*38 mm. in length by O'io 0-24 mm. 

 in breadth. They have leg-like palpi with three joints, hirsute 

 bodies, and very hairy legs composed of five segments terminating 

 with three ungues. l 



2. Fain. Tetranychidce (Spinning Mites). 



These have tracheae and eyes ; the palpi are composed of four segments, of 

 which the last but one has a powerful claw ; the antennas are two-jointed, the 

 first joint solid and transformed into a blunt cone from which the long, bent 

 stinging bristle (the second joint) protrudes. The legs have six segments 

 with sucker discs between the claws. 



Tetranychus molestissimus, Weyenbergh, i886. 2 



Found in Argentine and Uruguay on the under surface of the 

 leaves of Xanthium macrocarpum ; it attacks mammals and men, 

 producing . severe itching, accom- 

 panied by fever in the latter. 



It has been asserted by Haller 

 that the CAPE AILMENT (Port Natal 

 Sickness) is caused by mites, but 

 this statement has been contested. 3 



2. Tetranychus telarius (L.), 1758 4 

 (var. russeolus, Koch). 



This common spinning mite like- 

 wise attacks human beings, but 

 the papules produced by it very 

 soon disappear. 5 



FIG. 231. Tetranychus telarius, var. 

 russeolus, Koch (enlarged). (After 

 Artault.) 



1 Tanaka, Keis, " Ueb. JF.t. u. Pathog. d. 

 Kedani-Krankh." (Centr. f. Bak., Par. und 

 Inf., 1899 [r], xxvi., p. 432). 



2 [This species is also known as Bicho 

 Colorado. It spins a web under the lower 



surface of the leaves, and it is only from December to February that it attacks warm- 

 blooded animals and man. F. V. T.] 



8 Haller, G., " Vorl. Nachr. uber einige noch wenige bekannten Milben " (Zool. Anzgr., 

 1886, ix., p. 52 ; Fritsch, G., " Bern. z. Herrn Hatter's Aufs." (ibid., p. 229). 



4 [There is something wrong here, probably in the identification. T. telarius is purely 

 a plant feeder, and it is extremely unlikely a variety would attack man. Anyhow 

 it will not do so in Great Britain. F. V. T.] 



5 Artault, L., " Le platane et ses mefauts ; un nouv. Acar. paras, accid de Vhomme " 

 (Arch, de paras., 1900, hi., p. 115). 



