LITTING leisurely through the air on her green gauze wings, the lace-wing seems like a filmy leaf, broken loose and drifting on the breeze. But there is purpose in her flight, and through some instinct she is enabled to seek out an aphis-ridden plant or tree, to which she comes as a friend in need. As she alights upon a leaf, she is scarcely discernible because of the pale green of her delicate body and wings; however, her great globular eyes that shine like gold attract the attention of the careful observer. But though she is so fairy-like in appearance, if you pick her up, you will be sorry if your sense of smell is keen, for she exhales a most disagreeable odor when disturbed—a habit which probably protects her from birds or other creatures which might otherwise eat her.
However, if we watch her we shall see that she is a canny creature despite her frivolous appearance; her actions are surely peculiar. A drop of sticky fluid issues from the tip of her body, and she presses it down on the surface of the leaf; then lifting up her slender abdomen like a distaff, she spins the drop into a thread a half inch long or more, which the air soon dries; and this silken thread is stiff enough to sustain an oblong egg, as large as the point of a pin, which she lays at the very tip of it. This done she lays another egg in a like manner, and when she is through, the leaf looks as if it were covered with spore cases of a glittering white mold. This done she flies off and disports herself in the sunshine, care free, knowing that she has done all she can for her family.
After a few days the eggs begin to look dark, and then if we examine them with a lens, we may detect that they contain little doubled-up creatures. The first we see of the egg inmate as it hatches, is a pair of jaws thrust through the shell, opening it for a peep-hole; a little later the owner of the jaws, after resting a while with an eye on the world which he is so soon to enter, pushes out his head and legs and drags out a tiny, long body, very callow-looking and clothed in long, soft hairs. At first the little creature crawls about his egg-shell, clinging tightly with all his six claws, as if fearful of such a dizzy height above his green floor; then he squirms around a little and thrusts out a head inquiringly while still hanging on "for dear life." Finally he gains courage and prospects around until he discovers his egg stalk, and then begins a rope climbing performance, rather difficult for a little chap not more than ten minutes old. He takes a careful hold with his front claws, the two other pairs of legs carefully balancing for a second, and then desperately seizing the stalk with all his clasping claws, and with many new grips and panics, he finally achieves the bottom in safety. As if dazed by his good luck, he stands still for a time, trying to make up his mind what has happened and what to do next; he settles the matter by trotting off to make his first breakfast of aphids; and now we can see that it is a lucky thing for his brothers and sisters, still unhatched, that they are high above his head and out of reach, for he might not be discriminating in the matter of his breakfast food, never having met any of his family before. He is a queer looking little insect, spindle-shaped and with peculiarly long, sickle-shaped jaws projecting from his head. Each of these jaws is made up of two pieces joined length-wise so as to make a hollow tube, which has an opening at the tip of the jaw, and another one at the base which leads directly to the little lion's throat. Watch him as he catches an aphid; seizing the stupid little bag of sap in his great pincers, he lifts it high in the air, as if drinking a bumper, and sucks its green blood until it shrivels up, kicking a remonstrating leg to the last. It is my conviction that aphids never realize when they are being eaten; they simply dimly wonder what is happening.
Aphis-lion, eggs, larva, cocoon and the adult, lace wing.
It takes a great many aphids to keep an aphis-lion nourished until he gets his growth; he grows like any other insect by shedding his skeleton skin when it becomes too tight. Finally he doubles up and spins around himself a cocoon of glistening white silk, leaving it fastened to the leaf; when it is finished, it looks like a seed pearl, round and polished. I wish some child would watch an aphis-lion weave its cocoon and tell us how it is done! After a time, a week or two perhaps, a round little hole is cut in the cocoon, and there issues from it a lively little green pupa, with wing pads on its back; but he very soon sheds his pupa skin and issues as a beautiful lace-wing fly with golden eyes and large, filmy, iridescent, pale green wings.
Leading thought—The lace-wing fly or golden-eyes, as she is called, is the mother of the aphis-lion. She lays her eggs on the top of stiff, silken stalks. The young aphis-lions when hatched, clamber down upon the leaf and feed upon plant-lice, sucking their blood through their tubular jaws.
Method—Through July and until frost, the aphis-lions may be found on almost any plant infested with plant-lice; and the lace-wing's eggs or egg-shells on the long stalks are also readily found. All these may be brought to the schoolroom. Place the stem of a plant infested with aphids in a jar of water, and the acts of the aphis-lions as well as the habits of the aphids may be observed during recess or at other convenient times, by all the pupils.
1. When you see a leaf with some white mold upon it, examine it with a lens; the mold is likely to be the eggs of the lace-wing. Is the egg as large as a pin head? What is its shape? What is its color? How long is the stalk on which it is placed? Of what material do you think the stalk is made? Why do you suppose the lace-wing mother lays her eggs on the tips of stalks? Are there any of these eggs near each other on the leaf?
2. If the egg is not empty, observe through a lens how the young aphis-lion breaks its egg-shell and climbs down.
3. Watch an aphis-lion among the plant-lice. How does it act? Do the aphids seem afraid? Does the aphis-lion move rapidly? How does it act when eating an aphid?
4. What is the general shape of the aphis-lion? Describe the jaws. Do you think these jaws are used for chewing, or merely as tubes through which the green blood of the aphids is sucked? Do the aphis-lions ever attack each other or other insects? How does the aphis-lion differ in appearance from the ladybird larva?
5. What happens to the aphis-lion after it gets its growth? Describe its cocoon if you can find one.
6. Describe the little lace-wing fly that comes from the cocoon. Why is she called golden-eyes? Why lace-wing? Does she fly rapidly? Do you suppose that if she should lay her eggs flat on a leaf, that the first aphis-lion that hatched would run about and eat all its little brothers and sisters which were still in their egg-shells? How do the aphis-lions benefit our rose bushes and other cultivated plants?
Supplementary reading—"A Tactful Mother" in Ways of the Six-Footed.