9 
stance, and frequently 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 attaining full growth it does not, like the latter, aban- 
don the plant upon which it has fed until the final generation. Indi- 
cations are that there may be three and, in some seasons in .its 
southernmost range, perhaps four generations produced each year, 
larve occurring as early as the 1st of May and as late as the 1st 
of November. In northern Europe two generations are recognized." 
The larve of the earlier generations spin their cocoons (fig. 3, f), 
which are composed partly of silk and partly of a glutinous sub- 
stance, 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 egg period in late April and early in May has been observed 
in the District of Columbia to last for from seven to ten days, and 
the young larve begin feeding in the first and second weeks of May. 
Larve grow rapidly, and cocoons have been found by the middle of 
May. The pupal period observed was fifteen days, so that the second 
brood of flies may appear before the end of May. This second gen- 
eration begins work about the second week in June, but during July 
there is a comparative cessatton, presumably between the second and 
third broods of worms, when fresh growth is little affected. 
Mr. G. Pauls, St. Louis Altenheim, St. Louis, Mo., wrote in regard 
to observations conducted by him on this species at St. Louis in 1904. 
The sawfly continued depositing eggs up to September 17. October 
14 he placed larve in a jar; three transformed to pups October 17, 
19, and 24 and issued March 30 to April 10 of the following year. 
One larva pupated October 16 and issued March 22, having passed 
about five months in the pupal stage. This shows considerable varia- 
tion in the time of issuing indoors, and would probably be duplicated 
to a certain extent in the open. April 29 he observed the sawfly 
depositing eggs on the leaves. 
NATURAL ENEMIES. 
No natural enemies of this rose slug appear to have been recog- 
nized in America, but in Europe it is preyed upon by two parasites, 
Acrotomus lucidulus Gray. and Mesochorus cimbicis Ratz, 
@Various European authors have written on this species. One of the most 
accessible general articles is that by M. 8S. C. Snellen van Vollenboven, trans- 
lated from the Dutch by J. W. May and published in The Entomologist, Vol. 
VIII, 1875, pp. 26-29. 
[Cir. 105] 
