PSYLLIILE. 



365 



show that the individual leaflets are rolled towards the centre in a 

 somewhat oblique manner. The natural green colour of the leaf is 

 substituted by large brownish mottled streaks. As long as the injured 

 foliage is attached to the plant, the leaflets are comparatively stiff ; but 

 if removed from the stem, they soon get as flabby and tender as 

 tissue-paper. 



If the leaflets are unfolded we find a large quantity of "cotton- 

 wool," protecting larvae and eggs. This diversity in the phases of 

 development is therefore suggestive of the adult insects subsequently 

 appearing at Varying dates. 



As regards larvae and pupae, it is difficult to determine where the 

 one stage ends and the other begins, 

 except that after one or two larval 

 moults the wing - cases are more fully 

 developed, and the latter stages may 

 therefore be termed pupae. 



Fig. 340. Leaflets of ash injured by Psyllopsis fraxini. 



The adult insect is somewhat variable in colour. The head is a 

 reddish-yellow, with dark projecting eyes. Thorax a variable yellow 

 with black markings ; abdomen black above and yellow below. 

 Antennae ten -jointed, long and slender joints, becoming smaller 

 towards the apex ; last joint very small, and terminated by a forked 

 bristle. Wings, smooth in cells, veins, and even edges. Clouded at 

 edges. Legs a reddish-yellow. Length 2| to 3 mm. 



The clouded wings and brown markings of the body are quite 

 characteristic features of this species, inasmuch as the colour of the 

 insect harmonises in a very wonderful degree with the chocolate- 

 pinkish colour of the leaflets. 



