522 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 



young wild cherry trees. This was uudoiibtedly the uative food-plant 

 of this insect before the importation of peach trees. 



3. The cherry slug or pear slug. 



Selandria oeraai Peck. 



Order Hymenoptera ; family Tenthredinid.e. 



Fig. 182. —Cherry or pear slug; a, larva, enlarged three times. — From Packard. 



Saw-fly larvae, exactly like the pear-slug, occurred on the common 

 thorn at Brunswick, Me., August 1, in company with two other species 

 of Selandria. It also was observed in the same locality on the wild 

 cherry August 25. The following remarks by Professor Forbes in his 

 First Eeport on the Injurious Insects of Illinois for 1882, p. 98, will 

 prove of interest in this connection: 



Although this species was carefully studied and fully described by Professor Peck 

 in 1790, and also discussed at length by Dr. Harris iu his Insects Injurious to Vege- 

 tation in Massachusetts, I judge from numerous inquiries received this summer that 

 it is not as well known to horticulturists iu Illinois as it should be. As it has not 

 yet been treated in the reports of the State entomologists either of Illinois or Mis- 

 souri, a brief account of it and of the methods of meeting its ravages will not be 

 without value. 



This insect was quite abundant and destructive to the cherry throughout the 

 northern third of the State during the past summer, although I neither saw nor 

 heard of any especial iujury to other fruit trees. At Elgin, on the 18th of July, sev- 

 eral cherry trees were seen with their leaves completely denuded; and smaller num- 

 bers of the larvse were found on the cherry at Rockford, and on the pear and cherry 

 at Waukegan. It was also reported destructive to cherries at Montgomery, iu Kane 

 County, and was sent me by a correspondent from Aurora, on the 22d of July, where 

 it was said to have completely defoliated the Richmond cherry, and to have some- 

 what injured sweet cherries, pears, and the mountain ash. The effect of this destruc- 

 tion of the leaves in midsummer is to compel the tree to put forth new foliage, thus 

 taxing its vitality in a way to endanger the crop of the following year. As the larvie 

 return again for a second attack upon the trees in autumn, the consequences may 

 easily become serious. 



Description and life history. — The larvse, or slugs, as they are improperly called, are 

 white at first, but soon become covered with an olive slime, which gives them some- 

 thing of the appearance of the naked snail, to which the name slug properly belongs. 

 They are further easily distinguished from any other larvae feeding upon the leaf by 

 the fact that they are much thicker in front than behind, tapering gradually pos- 

 teriorly. They have twenty very short legs, the first three pairs jointed, the remain- 

 der fleshy prominences, commonly known as prologs. The head is of a dark chestnut 

 color, small, and usually concealed under the forepart of the body. They live mostly 

 on the upper side of the leaves of the trees, eating away all the parenchyma, leaving 

 only the veins and epidermis of the under side. The slugs shed their skins five 

 times, and after the last molt they lose their slimy covering and olive color, and are 



