52 SOURCES OF NECTAR 
other insects, including bees and wasps, are attracted to the feast 
when the product is abundant. 
At times the plant lice become so abundant on the leaves 
of the various trees on which they feed as to prove disastrous to 
the tree. Plum trees are especially liable to injury from these 
insects. When the leaves begin to curl in early spring, it is 
usually a sign that plant lice of some kind are present. Hundreds 
of them will be found under one leaf. 
It is usually from such forest trees as elm, hickory, and oak 
that honey-dew comes in sufficient quantities to be apparent 
in the hive. It is only in an occasional season that the bees 
gather honey-dew in noticeable quantities. At times it will fairly 
drip from the trees, and on such occasions, if no honey is coming 
in, the bees will work with tremendous energy in storing the 
substitute. 
There seems to be considerable variation in the quality of 
the honey-dew honey, but as a rule it is not of good quality, and 
a beekeeper should be very careful that it does not spoil his 
market for good honey. It is especially disastrous to the bees 
as winter food, and should never be left in the hive for winter 
stores, in the northern States, where the bees are confined for long 
periods without a flight. Where the bees are free to flv every few 
days during winter, the bad effect is not so apparent. (See 
Chapter XIII on Wintering.) 
Sources of Early Pollen—\While some pollen is gathered 
from the early spring flowers, the most important sources are 
the forest trees. The clm is especially valuable, as it vields pollen 
in enormous quantities. When the elm trees bloom, the 
bees fairly cover them until the humming reminds one of 
the swarming season. At about this same season the maples 
(Acer) bloom (Figs. 25 and 27). These trees furnish not only 
pollen, but nectar also, and are a valuable source of supply at this 
season. The willows (Salix) likewise furnish pollen in abund- 
ance and nectar beside (Figs. 25 and 26). At times the bees 
are able to store some honey from the two last named sources. 
