494 
HONEYDEW 
on the limbs, and others on the roots. 
Among the deciduous-leaved trees on which 
honeydew is very frequently found are 
oaks, beech, poplar, ash, elm, hickory, 
chestnut, maple, willow, basswood, gum 
trees, fruit trees, grapevine, currant, black¬ 
berry, and hazel. The aphids are so well 
known that they require only a brief de¬ 
scription. They are small, thick, usually 
greenish insects with pear-shaped bodies 
and long legs. On the back of the sixth 
abdominal segment of Aphis and Lachnus 
there is a pair of tubes called cornicles. A 
part of the forms are winged and a part 
are wingless. In the fall both males and 
females appear. The females are wing¬ 
less, but the males may be either winged or 
wingless. After mating the males soon 
die; the females lay one or more eggs, 
after which they die also. The eggs may 
often be found on the terminal buds of 
trees; e. g., on many of the terminal 
buds of the apple tree three or four 
minute black eggs are laid. Early in the 
spring the eggs hatch, but produce only fe¬ 
males known as stem-mothers. By bud¬ 
ding they give birth to living young instead 
of laying eggs. The second generation 
consists like the first wholly of females, 
from which again come living offspring. 
Reproduction under these conditions with¬ 
out pairing may continue for eight or more 
generations, until with the approach of 
winter both sexes are again produced. From 
time to time a part of the females are 
winged and thus provide for the spread of 
the species. The winged forms fly from 
tree to tree, and are likely to infest the 
tender upper growing shoots. Later they 
spread to the lower branches. Virgin re¬ 
production (parthenogenesis ), or the pro¬ 
duction of young without fertilization, is 
of special interest to the beekeeper, as 
worker bees are able to lay eggs which pro¬ 
duce only drones, and the unfertilized eggs 
of the queen also give birth to males alone. 
Plant-lice multiply with extreme rapid¬ 
ity and it has been estimated that the off¬ 
spring of each plant-louse, if all survived, 
would in 100 days amount to over 3,200,- 
000 individuals. Fortunately they are held 
in check by a vast number of parasitic in¬ 
sects, as syrphid flies, lady beetles, and 
plant-lice lions, or they would threaten the 
destruction of all vegetation. Their de¬ 
velopment is also probably greatly influ¬ 
enced by the weather. Occasionally there 
comes a year when plant-lice and scale-in¬ 
sects appear in hosts, and there is conse¬ 
quently a great abundance of honeydew, 
as in 1884 and 1909 in this country and 
1898 and 1907 in Great Britain. In 1909 
there was in eastern North America an un¬ 
precedented amount of honeydew, while 
the crop of white clover and basswood was 
almost a complete failure. Most of the 
honeydew came from the leaves of hickory 
and oak. While gathering it the bees were 
exceptionally cross. Since it became al¬ 
ternately partially liquid in the forenoon 
and gum-like in the afternoon, they were 
able to work on it only in the morning 
hours; the moisture in the air softened- it 
at night, but by noon the sun again dried 
it to a viscous state. Honeydew honey is 
often stored by the ton, and in certain lo¬ 
calities as in the Sacramento Valley, Calif., 
a crop is gathered almost every year. 
The dew is forcibly ejected or flipped 
from the end of the abdomen, and when 
there are many aphids falls in a spray of 
minute globules. If the dew were not thrown 
a little distance from their bodies they 
would soon be glued together. As they 
usually feed on the under side of the 
leaves, the sweet liquid naturally drops on 
the foliage beneath them. As it is gum¬ 
like it may dry and reihain on the leaves 
for a long time, so that the absence of 
plant-lice is no proof that it is of vegetable 
origin. If it is very abundant it may drip 
from the leaves to the ground. In 1891 
Busgen observed that a single plant-louse 
on a maple leaf produced 48 drops in 24 
hours (the drops were 1-25 of an inch in 
diameter), on a basswood leaf 19 drops, 
and on a rose leaf only 6 drops. The pro¬ 
duction of honeydew has been found to be 
most active in the middle of the day when 
the temperature is highest. The pair of 
tubes, or cornicles (also called siphons 
and nectaries) are commonly believed also 
to excrete honeydew; but this is denied by 
Forel and other entomologists, who assert 
that they exude only a gluey substance, 
which is not sought by ants. The tubes do 
not connect with the digestive tract, and 
the liquid which issues from them is pro¬ 
duced by glandular cells at their base. In 
