1906.] 



The Large Larch Sawfly. 



389 



family of Hymenoptera which has the greatest interest for the 

 forester is the Tenthredmidcs, or sawflies. The sawflies are so 

 called from the fact that the ovipositor of the female is modified, 

 typically, to form a sawing apparatus, by which the openings are 

 made in leaf or twig for the reception of the eggs. The two saws 

 are side by side on the under surface at the hind end of the 

 sawfly. The adult sawflies do not attract much notice, but if 

 examined it will be seen that they do not have the narrow waist 

 characteristic of the wasps, but that the base of the abdomen is 

 broadly joined to the thorax. The adults, in nearly every case, 

 are harmless, save that, of course, they lay the eggs. The larvae 

 are very characteristic : they are caterpillars, with more than^ 

 sixteen legs (the caterpillars of the genus Lyda, troublesome o.i' 

 fruit and forest trees, have eight legs, six in front and a pair 

 behind, and the corn sawfly, Cephus, if included under Tenthvedi- 

 nidcB, would be another exception), and they feed in the great 

 majority of cases exposed ; a few, however, live in galls, or 

 mine or burrow in plant tissue. Dr. Sharp reckons that 

 nearly 400 species h ive been found in Britain, and amongst 

 these are species troublesome in gardens, and to fruit, and in 

 agriculture. Six or seven genera contain species of importance 

 in forestry, of which Lophyriis (see Leaflet 103). Lyda, and 

 Neincitus are the most important. 



The species of the genus Neniatus that have relation to forestry 

 affect, amongst broad-leaved species, the willow chiefly. The 

 interesting, and sometimes injurious, caterpillars of Ncmatus 

 scptentrionalis, besides feeding on willow, attack also the leaves 

 of birch, hazel, alder, and mountain ash. On the larch, besides 

 Neniatus EricJisoui, the large larch sawfly, I notice later, for 

 comparison, Neniatus laricis, the small larch sawfly. 



Description of Neniatus EricJisoni. 



Adult. — The adult sawfly measures up to | inch, or a little 

 over, in length, and in spread of wings just less than an inch. 

 The ground colour is black. The head and thorax are black ; 

 the first joint of the abdomen is black ; then follow joints 

 coloured red ; the end of the abdomen again be'ng black. The 

 mouth parts, the two front pairs of legs, except at the part next 

 to the thorax, and the upper parts of the femora of the hind legs, 

 are reddish or reddish-yellow. The tibiae are yellowish or pale 

 in the upper parts. The antennae are nine-jointed and some- 



