84 THE EEPOET OF THE ENTOMOLOGICAL SOCIETY. No. 36 



their quarters kept in cleanly condition by getting rid of the cast-off skins which 

 are largely devoured by these active little scavengers. 



Because of their relation to disease, their parasitic habits upon man, animals 

 and plants, and their beneficial effects as scavengers, it is hard to over-estimate 

 their importance. There are at least eight well-defined diseases of man and 

 domestic animals, all isolated within the brief period of five years, which are trans- 

 mitted from host to host by means of these mites. Numerous species spread the 

 spores of bacterial and fungous diseases from affected organisms to healthy plants. 

 As animal parasites they are found upon insects, crustaceans, mollusks, fishes, 

 amphibians, reptiles, turtles, birds and mammals. As plant parasites, almost every 

 known plant is attacked by one or more of these hungry mites; and as scavengers 

 they are found on all decaying matter. In spite of their vast importance, not 

 much has hitherto been done in Canada in working out the different species and 

 determining their habits. This is in part due to their very minute size and also 

 to the, difficulty in locating them. For the little we do know, we are indebted to 

 Mr. J. B. Tyrrell, of Ottawa, for his investigations on Analgesids, and to the late 

 Dr. Fletcher for his contributions on the habits of some of our common species 

 of vegetable pests. In the United States much has been done in a systematic way 

 by Mr. Nathan Banks, Bureau of Entomology, Washington. 



The species in the list outlined in this report were in almost every case collected 

 in the vicinity of Guelph. This study was first taken up in 1904 and since that 

 time the writer has collected, examined and studied to some extent the habits and 

 characteristics of upwards of three hundred species, one hundred or more of which 

 are new and many of them belonging to genera new to North America. 



Mites are known to exist and to cause trouble in every part of the world, but 

 in the temperate zones the largest numbers of species abound. Usually they are 

 found in semi-dark localities, but a few species seem to enjoy full sunlight, being 

 found upon the upper surface of leaves. On account of their minute size, certain 

 species can be obtained only by use of special devices, such as mite traps; others 

 again, such as bird mites, which are nocturnal in habits, must be gathered at night ; 

 still others, as the Eriophyes, which closely resemble their surr.oundings, require 

 several days of constant search. Special emphasis should be laid \vpon the con- 

 struction and operation of the mite traps. The trap consists of a copper cone-shaped 

 vessel lined with tin, affording a smooth surface, to prevent the mites from attaching 

 themselves to the sides of the cones. Within the body of the outer cone are four 

 smaller cones, to the ends of which are attached small bottles, and in these the 

 material under examination is placed. The outer vessel is then filled with water 

 at a temperature much higher than the normal habitat of. the mites. The discom- 

 fort thus produced causes the mites to leave their host or habitat, and as almost 

 without exception. Arthropods when disturbed travel downwards, they slide 

 down the smooth inner surface of the cone into the bottle below, where they are 

 readily available for examination. Sometimes they are preserved in alcohol, some- 

 times mounted in glycerine jelly or balsam, and if intended for life history study 

 they are transferred to artificial media. 



The aquatic apparatus is made of the same materials as the terrestrial one, 

 viz., tin and copper. It works upon much the same principle as the one just des- 

 cribed, i.e., when an Acarid becomes uncomfortable the tendency is to go downwards. 

 But instead of applying heat as in the case of the land trap, a few drops of formalin 

 or alcohol is added to the aquatic material. The trap with the proper fittings may 

 be taken to a pond or stream where various kinds of material are available, and in 

 the course of a single day's work many species may be captured. 



