The Agents concerned in the Production of Galls 33 



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. 



The legs are four in number, all exactly the same size and 

 shape ; they are five-jointed, situated close to the head, and 

 always point forward. A very few small bristles are upon them. 

 Mostly they are furnished with a small claw, but some have a 

 knob instead. 



The tarsi have a number of fine bristles arranged upon them, 

 producing a feathered appearance. The colours are pure white, 

 yellowish white, orange-yellow, and brownish yellow when old. 



The ? lays great numbers of eggs, the membrane of which 

 is composed of chitin. In shape they are round, elliptical, or 

 ovid. When deposited late in the year they do not hatch in the 

 following spring, their vitality being destroyed by frost ; those 

 deposited in spring and summer hatch quickly. From them 

 emerge larvse very similar in appearance to the parents, and can 

 be distinguished only by slighter size, a less number of sitce, and 

 absence of sexual organs exteriorly. Ecdysis occurs twice at 

 least during the larval stage, the sex not being manifest until 

 after the second. The nymphal stage is characterised by the 

 progress of development, and a slight protrusion of the sexual 

 organs. 



The imagines spend the winter on plants — by preference in 

 the buds — and in the ground. Some species exude a flocculent 

 substance from portions of the back. They are very sensitive 

 to the action of light upon their bodies, and evade the sunlight 

 which kills them. They do not all make galls ; some live as 

 parasites and inquilines upon those which do. Their two chief 

 enemies are gamasides, which attack them when away from the 

 galls, and a fungus (sp. ?), the hyphse of which penetrate the 

 body and cause death. 



The foregoing notes are derived mainly from Dr. Nalepa's 

 publications. 



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