522 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
young wild cherry trees. This was undoubtedly the uative food-plant 
of this insect before the importation of peach trees. 
:{. The chbrby slug or peak slug. 
Selandria a rani Peek. 
Order Hymexoptera ; family Tknthreuixih 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 Bruuswick, 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 Report 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 in 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 injury 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 larvae were found on the cherry at Rockford, and on the pear and cherry 
at Waukegan. It was also reported destructive to cherries at Montgomery, in Kane 
County, and was sent me by a correspondent from Aurora, on the 2'2d 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 larvae 
return again for a second attack upon the trees in autumn, the consequences may 
easily become serious. 
Description and life history. — The larvae, 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 prolegs. 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 aud olive color, and are 
