Tetranychidae 257 



is added to water containing the mites they immediately show a negative 

 response to light and maintain this state for a length of time depending 

 somewhat on the concentration of host substance. 



It may be further shown that this reversal in phototropism is due to 

 specific host material for if water from the mantle cavity or extract of 

 gills of mussels on which this species of mite is not parasitic is used there 

 is no effect on the phototropism of the mites and they remain positive to 

 light. 



The parasitic Unionicola may be identified by reference to papers by 

 Wolcott (1899, 1905) and Marshall (1933). 



Reference 

 For the culture of Hydracarina see p. 136. 



Bibliography 



Marshall, Ruth. 1933. Preliminary list of the Hydracarina of Wisconsin, 



Part III. Trans. Wis. Acad. Sci. Arts and Letters. 28:37. 

 Welsh, J. H. 1930. Reversal of phototropism in a parasitic water mite. Biol. 



Bull. 59:165. 

 1931- Specific influence of the host on the light responses of parasitic water 



mites. Ibid. 61:497. 



1932. A laboratory experiment in animal behavior. Science 75:591. 



Wolcott, R. H. 1899. On the North American species of the genus Atax (Fabr.) 



Bruz. Trans. Amer. Micr. Soc. 20:193. 

 1905. A review of the genera of the water mites. Ibid. 26:161. 



Family tetranychidae 



J 



BREEDING OF NEOTETRANYCHUS BUXI, A MITE ON 



BOXWOOD 



Donald T. Ries, Ithaca, New York 



THESE mites may be found on the underside of the leaves of Box- 

 wood bushes in some localities. 

 Small cuttings of boxwood about an inch in length were placed 

 in small pots of earth. The pots of cuttings were then placed in 

 large flats of peat moss in order to facilitate handling and also to keep 

 them from drying out. Since the mites seemed unable to negotiate the 

 distance between the pots over the moss there w r as no need of covering 

 the individual plants. By this means mites were reared through nine 

 generations. 



Each female was allowed to deposit one or two eggs on a plant and 

 every 24 hours was removed to another plant by means of a fine camel's 

 hair brush. In no case were more than two nymphs allowed to live on 

 any one plant. 



