484- Insects most injurious to Cultivators : — 



the head retracted within the prothorax ; but, during the night, 

 it crawls slowly about from branch to branch. The exuviae 

 of the larvae {Jg. ,,4 



123. o) remain at- 

 tached to the leaves, 

 and appear like a 

 short slender black 

 thread with a shiny 

 head. Some of these 

 larvae, from the white 

 thorn, collected pre- 

 viously to the middle 



of August, underwent their penultimate change of larva skin 

 on the 16th of that month, and enclosed themselves in their 

 cocoons on the 18th of the same month; the perfect insects not 

 being produced until the following June and July. The cocoon 

 {^g- 124. h) is very similar to that of the turnip saw-fly; being- 

 brown, and externally covered with particles of earth, fastened 

 together with silken threads. The retraction of the head within 

 the prothorax is of service to the insect whilst feeding, since it 

 is thereby enabled to move its head in various directions, without 

 changing its situation ; and hence it remains stationary until it 

 has eaten every part of the surface of the leaf within reach ; when 

 it moves a little further on : its movements, however, are ex- 

 tremely sluggish. The last segment of the body is generally 

 elevated ; so that when the insect discharges its excrement, it is 

 compelled to employ considerable force, whereby it is shot 

 upwards to some height. I have seen them occasionally fall 

 upon the slimy back of the insect; but the grub has immediately 

 removed them by twisting its body in various directions, fasten- 

 ing them with slime upon the leaf. When about to change their 

 skin, they retire to the under side of the leaf, where they remain 

 until they have acquired their new coat of slime. Immediately 

 after they have changed their skin, they are of a clay colour, 

 and destitute of slime ; at which time they will occasionally 

 bend their bodies, so as to make the head and tail meet. The 

 secretion is rather glutinous, and has a strong scent, somewhat 

 like that of red ink. 



De Geer states that some of these larvee, which he examined, 

 enclosed themselves in cocoons at the beginning of October, the 

 perfect insects appearing at the end of the following July; 

 having thus passed nearly ten months in the inactive state. The 

 female deposits her eggs on the upper surface of the leaves, by 

 the assistance of her curiously formed ovipositor ; and, in a 

 few days, the young are produced. 



This insect was known to Linnaeus, by whom it was described 

 as the saw-fly of the cherry, Jenthr^do cerasi ; which name, as 



