22 FOREST ENTOMOLOGY. 



the abdomen. The head terminates in a snout-like projection, and 

 the maxillary palpi are used as antennae. 



The group is known as the " four-footed " mites, and when viewed 

 from the under side the four legs can be seen distinctly. The articula- 

 tions of the legs, although well marked, are rather difficult to deter- 

 mine. The tarsus, or foot, is provided with a double claw : one half 

 is terminated by a few fine bristles, called by the Germans " Fieder- 

 borste," or feather bristles, and the other half is a simple claw. 



The abdomen is divided into a series of from 60 to 90 ring-like 

 segments, according to species, and there are several hairs on the 

 abdomen. These are variable in size, but should, as far as 

 practicable, be noticed under the microscope, whether the dorsal, 

 ventral, or side aspect of the creature is being presented for examina- 

 tion. The rings, hairs, and the regular or irregular markings afford 

 good points for classification. At the extremity of the body are 

 two very long hairs, and rather important claspers, which the creature 

 uses as a means of anchorage. Doubtless, also, the hairs assist the 

 mite in the act of locomotion. 



The eggs are round or elliptical. There are two rather indistinct 

 stages, larva and nymph. The species in the buds of black currant 

 and hazel lend themselves for periodical examination, and the mites 

 can be seen in their various metamorphic stages. 



As regards the physiological functions of the mites, the following 

 notes from Mr Connold ^ may be quoted — viz. : 



" The mites have no special respiratory or circulatory organs. The 

 exchange of gases takes place through the body ; nor is there any 

 organ like a heart. The fluid, therefore, which is analogous to 

 blood, moves freely and irregularly throughout the body. The 

 nerves are in four pairs. The cesophagus passes through the brain 

 ganglia. 



" They are devoid of stomach, digestion taking place in the larger 

 intestine. Salivary glands are wanting, and also Malphigian tubules. 



"The skin is an exceedingly thin, colourless layer of chitin. 

 Beneath it lies a network of branched cells, which contain slight 

 colouring pigments." 



From a botanical point of view, or as regards the injuries done to 

 the host-plant, the mites may be divided into three great classes — 

 viz., those feeding within the buds, and consequently causing "blind 

 1 British Vegetable Galls, by Edward T. Connold, 1901, pp. 32, 33. 



