Notes on Tyroghj'phidse. By A. D. Michael. 25 



health. The advantage of the hypopial condition to the present 

 species is evident; the adult is a creature incapable of rapid or 

 extended motion; its food-plant would frequently die down and 

 decay, and the whole colony would be in danger of extinction 

 were it not that the Hy^popus can use other more active creatures 

 as means of conveyance to new localities. 



It remains to be considered whether it is Hkely that this Acarus 

 really did destroy the Coccus of the apple-tree in the manner it is 

 credited with doing. I know that Mr. Kiley, whose opinion on all 

 questions of economic entomology should have very great weight, 

 considers that many of the TyroglypMdw are predatory : this is 

 contrary to the general view taken by arachnologists, and I am not 

 able to agree with him : a Tyrofjlyphus pressed by hunger may 

 occasionally attack other Acari or small insects, but, as far as my 

 observations extend, they do not habitually or as ordinary food 

 prey upon living creatures. They are themselves devoured by 

 numerous enemies, but I have not ever been able to find any 

 indications of their feeding upon other living animals ; nor do their 

 mouth-organs appear fitted for the purpose ; they are not in any 

 way those which we usually find in predatory Acarina, and they 

 are very similar to those which are possessed by the well-known 

 vegetable-feeders. I have carefully drawn these organs in the 

 present species (figs. 10 and 11), in order that arachnologists may 

 be able to judge of the probabilities in this respect. There is an 

 entire absence of the lancets and sucking apparatus which we 

 should expect to find in a predatory Acarus. The present species 

 clearly can live on vegetable food ; and, with its slow movements, 

 short and weak legs, and elongated defenceless body, does not 

 appear fitted for the capture of other creatures, but does seem 

 eminently adapted to the life of a cortical or sub-cortical vegetable- 

 feeder, and very analogous to others leading a similar existence, 

 such as the nymphs of Hophphora, &c. The Tijroglyphidse are, in 

 most instances, unquestionably vegetable-feeders, but they do 

 undoubtedly also feed very readily upon preserved or dried animal 

 matter of some sorts, as the owners of cheese, cantharides, or 

 collections of insects, know to their cost ; and it is to be re- 

 membered that a Coccus is a pecuhar insect, it does not show much 

 sign of life or much movement (excepting the winged males), and a 

 large portion of it is very like a preserved specimen, so that it is 

 possible that a Tyroglyphus not ordinarily predatory might regard 

 a Coccus as suitable for gastronomic purposes. 



I have appended to this paper a description of the species in 

 all stages ; and, to summarize the results, 1 conclude that it is a 

 species feeding primarily upon the bark of vegetables, and not 

 confined to the bark of one particular tree ; that the female is the 

 creature figured by Riley ; the male, now described and figured by 



