The Saw-Flies 



Several of the species of the genus Pontania which make the 

 curious galls on willow leaves are convenient forms for study, 

 and the full and careful life history of any one of them would be 

 a valuable contribution to science. 



The super-family Tenthredinoidea was formerly considered a 

 family — the Tenthredinidse — but it has been justifiably separated 

 by Mr. Ashmead into eleven distinct families. 



Life History of the "Pear Slug" 



{Ej'iocampoides limacina, Retzius.) 



This insect, the larva of which is commonly known as the 

 pear slug, belongs to the group which has the slimy caterpillars 



referred to above. In 

 fact, its scientific name, 

 liniacina, indicates this 

 fact, since Limax is aslug. 

 This slimy, dark olive- 

 green, slug-like creature 

 occurs commonly upon 

 the leaves of pear, cherry, 

 plum and allied fruit trees 

 during most of the sum- 

 mer. Frequently it occurs 

 in such extraordinary 

 numbers with the later 

 broods that the leaves of 

 the tree turn brown, die 

 and fall to the ground in 

 midsummer. Sometimes 

 when the slugs are very 

 abundant, the sound of the eating of myriads of mouths resem- 

 bles the falling of a fine rain upon the leaves. There are some- 

 times thirty or more feeding upon a single leaf. 



The adult insect is a small glossy black, four-winged fly, 

 about one-fifth of an inch in length. 



The eggs are laid in April and May. The ovipositor of the 

 female is thrust obliquely through the skin of the leaf from below, 

 not reaching through the upper surface, however. The saw 



76 



Fig. 47. — Pear Slug: a, adult saw-fly, female; 

 d, larva with slime removed ; c, same in nor- 

 mal state ; d, leaves with larvae natural size ; 

 a, b, c, much enlarged. (After Marlatt.) 



