Bugs, Cicadas, Aphids, and Scale-insects 
172 
enlarged.) 
tree root-louse 
plump-bodied, pale-green insects, some with two pairs of long, delicate, 
transparent wings, some without wings, common on flowers in conserva¬ 
tories and gardens and known as “green fly.” Other often-noticed kinds 
are the cockscomb gall-louse of the elm and the “blights” of various foliage 
trees, as alder-blight, beech-blight, elm- 
blight, etc., these “blight” aphids all 
secreting conspicuous white woolly masses 
of wax and most of them also excreting 
honey-dew, which is conspicuous on the 
leaves and on the sidewalks under the 
trees. 
Of more economic importance are 
, 24 VJ« S ° Uthem grai " ?‘ ant ; some of those plant-lice which infest 
louse, Toxoptera grammeum, winged ^ 
migrant. (After Pergande; much crop-plants, the extraordinarily ruinous 
grape-phylloxera, for example, the apple- 
and the woolly apple-aphis, the cherry-, plum-, and 
peach-aphids, the corn-root louse, the hop-louse, and the cabbage-aphis, 
turnip-louse, and other aphid pests of garden vegetables. All of these 
insects are minute soft-bodied defenceless creatures, which effect their great 
injuries to their host-plants by virtue 
of great numbers. Fitch, New York’s 
first state entomologist, estimated the 
number ' of cherry-aphids that were 
living at one time on a small young 
cherry-tree to be 12,000,000. Although 
uncounted millions of the toothsome 
juicy little aphid bodies are being con¬ 
stantly eaten in spring and summer by 
eager predaceous insects, such as lady¬ 
bird beetles, certain syrphid-fly larvae 
and aphis-lions (larvae of lace-wing and hemerobius flies), just as constantly 
are new millions being produced by the fecund aphis mothers, most of the 
young being born alive and requiring but a few days to complete their 
growth and development, and to be ready to take up the production of 
young themselves. 
Professor Forbes has made an estimate of the rate of increase of the corn- 
root louse that shows this great fecundity. A single stem-mother of the 
corn-root aphis produces twelve to fifteen young that mature in a fortnight. 
“Supposing that all the plant-lice descending from a single female hatched 
from the egg in spring were to live and reproduce throughout the year, we 
should have coming from the egg the following spring nine and a half tril- 
As each plant-louse measures about 1.4 mm. in length and .93 
Fig. 245.—The southern grain-louse, 
Toxoptera gramineum, wingless. A, 
female; B, young nymph; C, older 
nymph. (After Pergande; much en¬ 
larged.) 
lion young. 
