THE NEMATIM OF NORTH AMERICA. 
INTRODUCTION. 
The subfamily Ncmatincv of Thompson or Nematina of Cameron 
(Konow's subtribe Nematides) comprises a very large group of closely 
allied species, distributed in the classification adopted by the author 
among nearly a score of genera. They range from very small insects to 
medium sized, but include no very large species, or in length from 2 to 
12 mm. They are for the most part smooth, shining, and rather soft 
bodied, and are variously colored, but yet presenting frequently a 
confusing similarity in general form, and particularly in coloration, 
rendering their generic and specific references in some cases difficult. 
In point of number of species and abundance of individuals this sub- 
family far exceeds any other of the corresponding groups in the family 
Tenthredini(he, and in variation and peculiarities in larval habits and 
in economic importance many of the species belonging to it have a 
very great interest. 
Geographical distribution. — The Nematinse are distinctly northern in 
their range, reaching their greatest development in abundance of species 
and specimens in the transition and boreal zones, and extend north- 
ward into circumpolar regions — species occurring abundantly in Green- 
land, Iceland, and Spitzbergen. Southward they become less and less 
numerous, and are practically wanting in tropical countries. This is 
illustrated very forcibly in Europe by the occurrence of over 70 species 
of the old genus Nematus in Scotland (Cameron) and 95 in Sweden 
(Thompson), as against 12 about Naples, Italy (Costa); and the same 
discrepancy exists between the temperate and subarctic region of 
America and the Southern States and Mexico. 
Food-plants — Their food-plants cover a wide range, some species affect- 
ing grasses, one or two very destructive ones the grains, others various 
deciduous trees and shrubs, and still others conifers. The majority of 
the species occur, however, on plants of the families Salicaceae, Betu- 
laceae, Rosacea?, and Conifera3, in the order given. 
Life history and habits. — The Nematines are among the first sawflies 
to appear in spring, occurring abundantly on trees at the first appear- 
ance of the leaves. They do not often frequent flowers, except, at least, 
those of the plants upon which their larvae feed. Many willow species, 
for example, occur abundantly on the earliest spring bloom of the willow. 
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