Bugs, Cicadas, Aphids, and Scale-insects 175 
Weed as follows: “It winters over on the twigs in the egg state. Early 
in spring the young aphids hatch and crawl upon the bursting buds, insert¬ 
ing their tiny sap-sucking beaks into the tissues of the unfolding leaves. 
In a week or ten days they become full-grown and begin giving birth to 
young lice, that also soon develop and repeat the process, increasing very 
rapidly. Most of the early spring forms are wingless, but during June 
great numbers of the winged lice appear, and late in June or early in July 
they generally leave the cherry, migrating to some other plant, although 
we do not yet know what that plant is. Here they continue developing 
throughout the summer, and in autumn a winged brood again appears and 
migrates back to cherry. These migrants give birth to young that develop 
into egg-laying females which deposit small, oval, shining black eggs upon 
the twigs.” 
The point of all this is plainly that in the aphids there must be recog¬ 
nized an unusual and, to them, very advantageous adaptive plasticity of both 
structure and function. Defenceless as are the aphid individuals as far 
as capacity either to fight or to run away is concerned, the various aphid 
species are, on the contrary, very well defended by their structural and physi¬ 
ological plasticity and their extraordinary fecundity. 
The two secretions, wax and honey-dew, play an important part in the 
aphid life. The wax secreted or excreted through various small openings 
scattered over the body is, of course, liquid when first produced, but quickly 
hardens; the total waxy secretion appears usually as a mass of felted threads 
or “wool,” and doubtless is an important protection for the delicate body. 
The honey-dew, long supposed to be secreted through two conspicuous 
tubular processes on the dorsal surface of the posterior end of the abdomen, 
is now known to be an excretion from the intestine, issuing in fine droplets 
or even spray from the anal opening. From the so-called “honey-tubes” 
issues another secretion, not sweetish, about which little is known. It is 
common knowledge, however, that the aphid honey-dew is a favorite food 
of ants—the Germans call it the ants’ “national dish”—and many accounts 
have been written of the care of plant-lice, the ants’ cattle, by the ants them¬ 
selves. Without question there is some basis of fact for these stories. No 
more evidence of this is needed than the careful observations of Professor 
Forbes of the extraordinary care of the corn-root louse by the little brown 
ant, Lasius brunneus, of the Mississippi Valley corn-fields (see p. 545 for an 
account of this). The feeding by ants on the fresh honey-dew can be readily 
observed in almost any garden (Fig. 247), and undoubtedly the mere presence 
in the aphid neighborhood of such redoubtable warriors as the ants is a 
strong deterrent of various predaceous insect enemies of the plant-lice. 
But most of the stories of ants and aphids printed in popular natural-history 
books need to be tested by careful observation. 
