276 INSECTS AFFECTING VEGETATION 



It is a larger insect and also a member of a different genus. The 

 wing expanse is about one-half of an inch for the female; a little 

 shorter for the male. The ground color is black. The antennae are 

 rather stout and acutely pointed, and in the male the proximal joints, 

 or those nearest the head, are pectinate or comb-toothed, which has 

 given rise to the specific name pectinicornis. The egg is white, flat- 

 tened, rounded, stoutest at the anterior end, and more pointed at the 

 opposite end. It measures about 0.8 mm. in length. 



The larva or slug varies from yellowish to glaucous green, and 

 the whole surface is quite bristly, especially at the sides, a character 

 from which this larvae derives its common name and which will dis- 

 tinguish it from the other two that feed upon the rose. The length 

 when full grown is a little more than three-fifths of an inch and the 

 diameter is between one-tenth and two-tenths of an inch. The pupa 

 is grayish green, the thorax and end of the body are slightly yellow- 

 ish, and the antennae, wing-sheaths, and legs are white with a slight 

 greenish tinge. The distribution includes the States of Massachusetts, 

 Connecticut, New York, New Jersey, Pennsylvania, Maryland, the 

 District of Columbia, Indiana, Illinois, and Missouri. 



The bristly rose slug differs considerably from the preceding in 

 its life economy. Its appearance at Washington, D. C., and at St. 

 Louis, Mo., has been observed from the latter days of April to the 

 third week of May, beginning about the time that the first rose leaves 

 are put forth. Its eggs are inserted in the upper surface of the petiole 

 of the leaf and are deposited in rows of three or more together. The 

 slug in its earliest stage skeletonizes the leaves, leaving whitish 

 blotches and small holes, but with increased growth it eats large, ir- 

 regular holes in the leaf, devouring the entire substance, and fre- 

 quently leaving nothing but the stronger ribs. While feeding, the 

 slug rests in concealment on the lower surface of a leaf, and does not 

 feed on the upper surface, as does the American rose slug. Upon at- 

 taining full growth it does not, like the latter, abandon the plant upon 

 which it has fed until the final generation. Indications are that there 

 may be three and, in some seasons in its southernmost range, perhaps 

 four generations produced each year, larvae occurring as early as the 

 1st of May and as late as the 1st of November. The larvae of the 

 earlier generations spin their cocoons, which are composed partly of 

 silk and partly of a glutinous substance, upon the lower surface of 

 the leaves, or on twigs or near-by objects, usually surrounding them 

 with an irregular fringe. The last or autumn generation forms its 

 cocoons among fallen leaves and other rubbish about the base of the 

 rose bushes. 



The same remedies advised against the American rose slug are 

 employed against the present species, with the exception of fall cul- 

 tivation, which is practically useless when applied to it, owing to the 

 fact that the cocoons are formed upon the plants on the surface of 

 the ground and not buried in the earth as with the preceding species. 

 Since there are more than one generation of this slug, sprinkling 

 with water and spraying with poisons must be repeated several times 

 in order to produce the desired results; in short, as often as the in- 



