396 REPORT OF STATE BOARD OF HORTICULTURE. 



The pear slug is an old enemy of fruit trees, and while it has been known 

 in this country for over a hundred years as an American species, the inter- 

 esting fact that it is the familiar slug-worm pest of the pear and plum trees 

 of Europe has not hitherto been definitely ascertained. In Massachusetts, 

 toward the latter part of the last century, this insect became very destruc- 

 tive, and Prof. Wm. D. Peck prepared an admirable, illustrated account of 

 it under the title of " Natural History of the Slug- Worm, '' which was printed 

 in Boston in 1799 by the Massachusetts Society for the Promotion of Agri- 

 culture. The author obtained for the production the society's premium of 

 $50, and a gold medal. The account of this insect given by Professor Peck 

 is fairly complete and accurate, but for fifty years it has been out of print 

 and inaccessible, and I have not been able to consult it. Harris abridged 

 and condensed it for his account of the slug-worm in his '' Insects Injurious 

 to Vegetation, ' ' published in 1841, and later writei's have generally followed 

 Harris. 



In Europe this insect was one of the first of the injurious species that 

 attracted attention, and one of the earliest of the economic writers on in- 

 sects, Reaumur, in the fifth volume of his bulky work, published in 1740, 

 gives a short account of it, together with recognizable figures of the insect 

 in difi'erent stages, illustrating, also, the effect of its work on leaves. The 

 first description and name which stands out unquestioned is by Retzius (1783), 

 who describes the species as I'cnthredo lim((cina. 



Linne, in describing what seems to have been an entirely distinct insect, 

 which he called Tenthredn cerasi, quotes Reaumur's account of ,the slug- 

 worm, which he erroneously took as belonging to his species, and very gen- 

 erally since, therefore, the former has been called cerasi Linn. (Cameron). 



Professor Peck, in describing the insect, gave it the name suggested by 

 Linne, and was of the belief that the species occurring about Boston was at 

 most a mere variety of Linne 's species, meaning, however, the common 

 pear-slug fly of Europe. Later American writers have treated it as a native 

 species, and under the generic name of Selandria or Eriocampa, Peck has 

 had the credit for it in this country, and the fact that Peck himself asso- 

 ciated it with Linne's species has been generally overlooked. 



That the species so common in this country is identical with the slug-fly 

 of Europe has been fully established by a comparison of specimens from 

 Europe with abundant American material. 



In Europe this insect has been the subject of description by innumerable 

 authors, having received at least nine difl'erent specific names and having 

 been referred to some eight genera. In this country it has also been the 

 subject of many short notices, but of very few full accounts other than the 

 one published by Peck. 



The pear slug is an insect which is easily distributed with the soil about 

 the plants which it infests, and it has been so carried about the world until 

 it has made its way into practically every civilized country. It is known at 

 least to occur throughout Europe and America and in many of the British 

 colonies. The slugs have been found on a great many different plants, 

 Reaumus recording them on the plum and cherry, and especially pear, but 

 also on the oak, and a recent catalogue by Dalla Torre indicates their occur- 



