120 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
Many of these are interesting because of the peculiarity of form so 
characteristic of the group. Yet, considered economically, few if any 
species are ever so injurious to forest growth as to cause alarm (Os- 
born, 322; Van Duzee, 420). 
Famity CICADELLIDAE 
The leafhopper family is represented in the United States and Can- 
ada by over 2,200 species, many of which are injurious to various forms 
of vegetation. A great many species feed on forest or shade trees, but 
the members of this family are most distructive to cultivated plants 
and grains. 
The species are rather small, being 3 to 15 mm. in length. The an- 
tennae are located in front of and between the eyes. The hind tibia 
are about as long as the abdomen and are armed with a row of spines 
on each margin. As may be inferred from the common name, the hind 
legs are formed for Jumping. 
‘Injury by leafhoppers may be caused by feeding, in which case the 
leaves become brown and withered or curled, or fruit may be blasted. 
The eggs are often deposited in slits in leaves, stems, or twigs of host 
plants. This may cause definite injury. Leafhoppers s are frequently 
the means of inoculating the host with destructive viruses. This type 
of injury is, so far as is known, more prevalent on cultivated plants 
than on trees. 
Some of the more common leafhoppers on forest and shade trees 
are listed with their hosts, as follows: The Japanese maple leafhop- 
per, | Platymetopius| Japananus hyalinus (Osb.), on Japanese and 
Norway maples; /diocerus spp., on willow, poplar, and hawthorn; 
Macropsis spp. on willows and poplars; Oncopsis spp.. on birch, hazel, 
alder, and walnut; [ C7cadella| Neokolla gothica (Sign.), on many 
shrubs and trees, particularly willow; also species of Alebra, E'm- 
poasca, Lyphlocyba and Erythroneura on maples, elms, poplars, wil- 
lows, alder, hazel, eastern white pine, oak, birch, and dogwood. Many 
others could be listed. However, where any one species becomes so 
abundant as to require the application of control measures a contact 
insecticide may be used. Insecticides apphed while the insects are 
in the nymphal stage will give the best control (De Long, 732). 
Famiry MEMBRACIDAE 
In number of species and in diversified and grotesque forms the 
family Membracidae reaches its greatest dev elopment in the tropical 
and subtropical regions. The pronotum usually extends backward for 
a considerable distance, and may completely cover the abdomen. 
Pronotal development, prominent on many exotic species (fig. 20, A), 
becomes less so in the United States, although there are some rather 
extraordinary species in this country (fig. 20, B). Insects in this 
family have only two ocelli. The antennae are hairlike, poorly de- 
veloped, and situated below and in front of the eyes. The wings are 
usually membranous (Funkhouser, 775). 
Although the insects in this family are interesting in many respects, 
they are of little consequence in our forest- and shade-tree ec onomy. 
‘They may be encountered in the woods, and most frequently in open 
stands. A type of injury which is usually of shght importance, but 
