Why do aphides or plant lice increase so rapidly?

Because one impregnation not only renders fertile the eggs of the individual, but the animals produced from these, and the eggs of these again, unto the ninth generation. - Philos. Transactions.

Why are the aphides, so often seen on apple-trees, called white blight?

Because they are lodged upon the limbs of the trees in a hoary and cottony substance, beneath which these wingless creatures prey upon the tree by means of a beak terminating in a fine bristle : this being insinuated through the bark and the sappy part of the wood, enables the creature to extract, as with a syringe, the sweet vital liquor that circulates in the plant, till the tree perishes limb by limb. This insect produces its young alive, forming a cradle for them by discharging from the extremities of its body a quantity of long cottony matter, which becoming interwoven and entangled, prevents the young from falling to the earth, completely envelopes the parent and offspring, and serves as a vehicle for dispersing the wingless animal in tufts wafted by the winds from tree to tree throughout the whole orchard. When the long cottony vesture is removed, the insects are still enveloped in a fine short downy clothing, to be seen by a magnifier, proceeding apparently from every suture or pore of their bodies, and protecting them in their dormant state from the moisture and frosts of our climate. Mr. Knapp thinks the epithet, ' American blight,' may be correctly applied to this insect, but we have no sufficient authority to conclude that we derived the pest from that country.

Why are aphides never seen in the flower of the rose, although they infest the stalk leaves ?

Because of the odour of the flower.

Why are the larva of lace-winged flies called the lions of aphides?

Because they devour the latter with great voracity, sucking the juices of their victims with their crescent-shaped and hollow mandibles.

The transparent wings of some insects are so attenuated in their structure, that 50,000 of them, placed over each other, would not form a pile a quarter of an inch in height.