1912] Ewing and Webster — Mites Associated ivith the Oyster-Shell Scale 131 



with their sucker-Hke discs, and by the absence of the very long 

 bristles which are dragged l^ehind the abdomen in the case of the 

 second named species. 



Habits. This is the mite that was given much of the credit of 

 causing havoc among the oyster-shell scales up to the time of 

 Lignieres' work. Lignieres was the first to ascertain its true 

 relationship to the scale insects and their eggs, which is that of a 

 scavenger and not of a parasitic or predaceous enemy. 



It seems probable, also, that Shinier (1868) observed this mite, 

 from a short account of a species which he saw among oyster-shell 

 scales. He says: 



"The careful observer will not confound this Acarus {mains Shimer) with another 

 yellowish- white mite-like insect, that I find here on the bark of the trees; this runs 

 much more rapidly than my Acarus; its body is, in proportion to its size, much 

 longer, as it appears under my exploring glass. * * * j don't find it under any 

 of this year's scales, therefore I do not believe that it is an egg-eater, like my Aca- 

 rus; it may be a vegetable feeder, or possibly feeding on the decomposing matter 

 of the scales of former years." 



MoniezieUa entomophaga may be found among injured eggs of 

 the oyster-shell scale at almost any time of the year. They are 

 never found among fresh eggs of the scale insect, and only follow 

 up the work of other mites. 



This relationship was clearly seen by Lignieres, as the follow- 

 ing quotations from his article shows : 



* * * j'ai enferme plusieurs de ces Acariens (apres les avoir fait jeuner huit 

 jours) dans des coques de Kermes remplies d'oeufs; ces derniers sont restes intacts, 

 tandis que tons les Tyroglyphes sont morts au bout d' un mois envii-on. 



Quand, au contraire, je les enfermais avec des coques de Kermes maintenues un 

 peu humides, ils vivaient facilement. 



That this species does not feed upon the li^'ing scale insects, nor 

 upon their sound eggs is, we think, fully established. Our obser- 

 vations, which quite agree with those of Lignieres, may be summed 

 up in the following paragraphs. 



1. The species was never found among eggs that were all fresh, 

 nor attacking the live scale insects, but was found only in scales 

 that contained old eggs, eggshells or dead scale insects under- 

 going decomposition. 



2. The members of the family to which this species belongs are 



