264 INJURIOUS INSECTS 



years elapsed before it made its appearance in Milton, 

 where he then resided. It feeds only at night, except in 

 very cloudy weather, and exclusively upon the upper sur- 

 face of the leaf, from which it gnaws the soft portion, 

 leaving the veins intact. During the day it rests motion- 

 less on the underside of the leaf. 



The larval life of this insect extends over a period of 

 fourteen days, during which it moults four times. The 

 full-grown slug is rather more than one-third of an inch 

 in length, by one-ninth in diameter. The thoracic joints 

 are somewhat smaller and humped, but not puffed out 

 laterally, as in some closely allied species, nor has it, like 

 these, a slimy surface. The color is a translucent dull- 

 yellow, becoming more opaque at the last moult. Soon 

 after this it enters the ground, and incloses itself in a 

 fragile, earthen cocoon, within which it remains dormant 

 for many months, not changing to pupa until the follow- 

 ing spring. Harris's assertion that it is double-brooded 

 has long been doubted by careful observers, and is un- 

 questionably disproved by Miss Murtfeldt's experiments. 



Owing to the longevity of the flies and the different 

 dates at which they emerge, there is a succession of lar- 

 vae, covering a period of from four to six weeks; but they 

 are all of the same brood, and when once they have 

 entered the ground, that is the end of them for the sea- 

 son. 



The Rose-slug, like most other insects, has a large 

 number of natural enemies, but these are not yet ade- 

 quate to the task of keeping it in check. The attention 

 of florists has, therefore, been largely directed to the 

 discovery of some reliable artificial remedy. 



Various applications have been tried with more or less 

 success, among which the most certain in its effects is 

 whale-oil soap suds, made in the proportions of one pound 

 of soap to eight gallons of water. The objections to this 

 remedy are, that it has a disagreeable odor and is liable to 



