THE MORE IMPOKTi^NT FAMILIES OF ACARI. 



11^ 



muscles o£ the mouth-parts and feet, the brain and the salivary glands. The 

 tail-shaped body contains the entrails proper. They live in the sebaceous sacs^ 

 and hair-follicles of all kinds of mammals, especially in the face. Rarely they 

 cause scurfs. This is a very neglected groui), and worthy of more attention. 

 Parts of the attacked skin should be preserved in alcohol. The creatures lack 

 respiratory organs, and most probably they are related to, or perhaps even an 

 earlier stage of, Psorermtes simpler', which also lives in sebaceous sacs (Family 

 Cheletid^, see above, p. llo). 



(12) Zemiostigmata, or 



Fig. 22. — Eriophyes temiis, 

 Nalepa; dorsal side of fore- 

 part, and ventral side of entire 

 creature.— Copied from Nalepa, 

 Phytoptida, in Denk.Ak.AYien, 

 1891 , tab. 1 . 



Tetrapodili, or Eriophyid^e (Gall Mites). 

 They are elongate, transparent, minute crea- 

 tures without respiratory organs, which they 

 have entirely lost (hence the name of Zemio-^ 

 STIGMATA), and with only four anteriorly placed 

 legs (fig. 22). Probably they are most nearly 

 related to, or perhaps even an earlier stage 

 of Tetronychid.e (see above, p. 113). They 

 generally cause various kinds of '' galls/^ 

 excrescences and deformities of leaves, buds, 

 twigs, etc., within which they live, and Avhich 

 are filled, or covered, with white hairs or 

 down. A few species live free^ but always on 

 leaves, especially on the underside. The galls 

 or defoi'mities must be separated from the 

 plant, then set aside in shadow, so that they 

 may dry a little ; then cut them into pieces,, 

 put them into a wide and short glass tube, 

 closely corked, and placed in a remote corner 

 of the room. After a time it will be observed 

 that all the minute creatures have come 

 together on the window -side of the tube. 

 Uncork the tube, cautiously remove all the 

 pieces, and fill it with spirits. As these mites 

 are extremely delicate, never put the labels- 

 into the tube, but paste them outside. 



