INSECT ENEMIES OF EASTERN FORESTS Are 
aud these in turn give birth to more living young, also all females. 
This goes on until a variable number of generations have been pro- 
duced on the primary host, when the next form appears. This is a 
winged form, which migrates to the secondary host. These are also 
parthenogenetic females, which give birth to living young. After be- 
coming established upon a secondary host, wingless females are again 
produced for a variable number of generations until winged forms are 
born which migrate back to the primary host, where they give birth 
to true sexual forms, males and females. ; 
After mating, the females deposit from one to several eggs, de- 
pending on the species. In some tribes of aphids the egg-laying fe- 
males are winged, the males are commonly winged, and both sexes 
have beaks and feed as do the asexual females. In other forms the 
males and females are small, wingless, and beakless, and each female 
deposits only one egg. Sometimes the egg is not even deposited but 
remains inside the shriveled body of the dead female over winter, to 
hatch in the spring or whenever favorable weather permits. The 
change from one form to another may be brought about not only by 
the season of the year but by lack of moisture or too much of it, 
overcrowding of the population, or change in food conditions. The 
following papers discuss these habits more fully; Baker (73), Balch 
(16), Gahan (177), Gillette and Palmer (7/85), Hottes and Frison 
(235), Johannsen and Patch (2556), Patch (337, 338, 339, 340, 341, 
343, 344). 
SUBFAMILY APHINAE 
Included in the subfamily Aphinae are most of the free-living 
aphids that ordinarily feed on the fohage of plants. Some of these 
may cause curling or distortion of the leaves, but such deformations 
are not true galls. Other species in the group also feed on the stems 
or roots of plants. Both males and females have functional mouth 
parts. Winged males are common and in some species the egg-laying 
females are winged and lay several eggs each. On conifers the eggs 
are laid in rows on the needles and generally are black, although 
sometimes they are covered with a white powder, which gives them 
a grayish appearance. 
TrinE LACHNINI 
In this tribe the species Longistigma caryae (Harr.) and Cinara 
strobi (Fitch) may cause real injury to forest trees. In addition, the 
following species are sometimes encountered: Anoecia querci (Fitch) 
on dogwood; Cinara abietis (Fitch) on black spruce; C. curvipes 
(Patch) on balsam, white, alpine, noble, and Spanish firs and on 
Atlas cedar; C. laricis (Wlkr.) on various species of larch; Hulachnus 
rileyi Williams on Scotch, shortleaf, eastern white, and ponderosa 
pines; and Lachnus salignus Gmel. on willow and poplar. These 
aphids range in size from 1.5 mm. in A. querci to 6 mm. in L. caryae. 
Longistigma caryae is one of our largest: aphids, its body being 
about 6 mm. long. It attacks a wide variety of trees, both in the 
forest and when used as ornamentals, as follows: Hickory, pecan, elm, 
sycamore, oaks, maples, lindens, chestnut, birch, beech, black walnut, 
and willow. It occurs over most of the eastern half of the United 
States, ranging from New England to Minnesota on the west and 
792440°—49—_9 
