12 



others consume the mature foliage. The greater number cause no 

 perceptible injur}^, jet there are some, like the forest tent caterpillar, 

 the pine butterfly, the western hemlock span-worm, etc., which are 

 capable of widespread devastation. 



FALSE CATERPILLARS. 



These are the larva? of a class of insects which are related to the 

 bees, but have very peculiar habits as compared with other insects of 

 the order (Hymenoptera) to which they belong. The adults are called 

 sawflies, on account of the peculiar saw-like ovipositor, by means of 

 which they make incisions in the living plant tissue for the reception 

 of their eggs. The larvae are often found in great numbers on pine, 

 dogwood, birch, elm, cultivated currant, etc., completely defoliating 

 the plant in a short time. Some of the species are capable of wide- 

 spread destruction of certain kinds of trees, as, for example, the 

 larch sawfly {Nematus erichsonii), which between 1882 and 1885 

 destroyed to an alarming extent the eastern larcl^ or tamarac in New 

 England and Canada. 



THE LEAF-BEETLES. 



This is a class of defoliators of which both the adults and the larva? 

 feed on the leaves. The willow and elm leaf -beetles are common 

 examples of the more destructive kinds. 



GALL INSECTS. 



The galls on the leaves of various trees are produced in great vari- 

 ety by several distinct classes of gall -making insects. As a rule, each 

 species, or a class of allied species, make galls of peculiar forms, by 

 which the species or class to which they belong may be identified. 

 Some galls are caused by four-winged gnats of the order Hymenop- 

 tera, others of the two-winged gnats of the order Diptera, and still 

 others by plant-lice, Psyllids, etc., of the order Hemiptera. 



PLANT-LICE. 



This is a class of soft-bodied insects which cluster in great numbers 

 on the leaves, injuring them by sucking out their sap, causing a faded 

 or curled appearance, and often doing serious damage. 



INSECTS INFESTING THE TWIGS. 



TWIG-BEETLES. 



These are small bark-beetles, whioh confine their operations to the 

 smaller twigs, and either mine under the bark or into the pith. They 

 rarely attack living twigs, but are exceedingly abundant in those of 

 dying and recently felled trees, and may in some cases contribute to 

 the rapid death of trees attacked by other insects. 



