Insect Adventures

<h2 id="chapter-14"><ANTIMG src="images/i_161.jpg" alt="" /><br/> CHAPTER XIV<br/> <span class="chapter-title">THE CABBAGE-CATERPILLAR</span></h2> <p><span class="upper">The</span> cabbage is the oldest vegetable we possess. We know that people in classic times ate it, but it goes much further back than that, so that indeed we are ignorant of when or how mankind first began cultivating it. The botanists tell us that originally it was a long-stalked, scanty-leaved, ill-smelling wild plant which grew on ocean cliffs. History pays but little attention to such details: it celebrates the battlefields on which we meet our death, it thinks the plowed fields by which we thrive are not important enough to speak of; it can tell us the names of kings’ favorites, it cannot tell us of the beginning of wheat! Perhaps some day it will be written differently.</p> <p>It is too bad that we do not know more about the cabbage, for it would have some very interesting things to teach us. It is certainly a treasure in itself. Other creatures think so besides man; and <SPAN name="page-162" class="pagenum" href="#page-162" title="162"></SPAN> one of these is the Caterpillar of the common Large White Butterfly. This Caterpillar feeds on the leaves of the cabbage and all kinds of cabbagey plants, such as the cauliflower, the Brussels sprout, the kohlrabi, and the rutabaga, all near relatives of the cabbage.</p> <p>It will feed also on other plants which belong to the cabbage family. They are all of the order of the Cruciferæ, so-called by the botanists because the petals are four in number and arranged in a cross. The White Butterfly lays her eggs only on this order of plants. How she knows them is a mystery. I have studied flowers and plants for fifty years and more, yet, if I wished to find out if a plant new to me was or was not one of the Cruciferæ, and there were no flowers or fruit to guide me, I should believe the White Butterfly’s record on the matter sooner than anything I could find in books.</p> <p>The White Butterfly has two families a year: one in April and May, the other in September. This is just the time that cabbages are ripe in our part of the world. The Butterfly’s calendar agrees with the gardener’s. When there are provisions to be eaten, the Caterpillars are on hand.</p> <div class="figcenter"> <ANTIMG src="images/i_162.jpg" alt="The eggs are a bright orange-yellow" /></div> <p>The eggs are a bright orange-yellow and are laid in slabs, sometimes on the upper surface, sometimes on the lower surface of the leaves. The Caterpillars <SPAN name="page-163" class="pagenum" href="#page-163" title="163"></SPAN> come out of their eggs in about a week, and the first thing they do is to eat the egg-shells, or egg-wrappers, before tackling the green leaves. It is the first time I have ever seen the grub make a meal of the sack in which it was born, and I wonder what reason it has. I suspect as follows: the leaves of the cabbage are waxed and slippery. To walk on them without falling off, the grub needs bits of silk, something for its legs to grip. To make this silk, it needs special food; so it eats the egg-wrapper, which is of a horny substance of the same nature as silk, and probably easily changed to the latter in the stomach of the little grub.</p> <div class="figcenter"> <ANTIMG src="images/i_163.jpg" alt="Soon the grubs get hungry for green food" /></div> <p>Soon the grubs get hungry for green food, and then the ruin of the cabbages commences. What appetites they have! I served up to a herd of these Caterpillars which I had in my laboratory a bunch of leaves picked from among the biggest cabbages: two hours later nothing was left but the thick middle veins. At this rate the cabbage bed will not last long.</p> <p>The gluttonous Caterpillars do nothing at all but eat, unless we except a curious motion they sometimes indulge in. When several Caterpillars are grazing side by side, you sometimes see all the heads in the row briskly lifted and as briskly lowered, time after time, all together and as accurately as if they <SPAN name="page-164" class="pagenum" href="#page-164" title="164"></SPAN> were Prussian soldiers drilling. I do not know whether this is their way of showing that they would fight, if necessary, or a sign of pleasure in the eating and the warm sun. Anyhow, it is the only exercise they take until they are full-grown and fat.</p> <p>After a whole month of grazing, the Caterpillars at last have enough. They begin to climb in every direction. They walk about anyhow, with the front part of their bodies raised and searching space. It is now the beginning of cold weather, and my Caterpillar guests are in a small greenhouse. I leave the door of the house open. Soon the whole crowd have disappeared.</p> <p>I find them scattered all over the neighboring walls, some thirty yards off. They are under ledges and eaves, which will serve them as shelters through the winter. The Cabbage-caterpillar is hardy and does not mind the cold.</p> <p>In these shelters they weave themselves hammock cocoons and turn into chrysales, from which next spring the Moths will come.</p> <div class="figcenter"> <ANTIMG src="images/i_164.jpg" alt="they weave themselves hammock cocoons and turn into chrysales..." /></div> <p>We may be interested in the story of the Cabbage-caterpillar, but we know that there would be not <SPAN name="page-165" class="pagenum" href="#page-165" title="165"></SPAN> enough cabbages for us if he were allowed full sway. So we are not ill-pleased to hear that there is still another insect who preys upon him and keeps him from being too numerous. If the Cabbage-caterpillar is our enemy, this insect is our friend. Yet she is so small, she works so discreetly, that the gardener does not know her, has not even heard of her. If he were to see her by accident, flitting around the plant which she protects, he would take no notice of her, would not dream of the help she is giving him. I am going to give the tiny midget her deserts.</p> <div class="figcenter"> <ANTIMG src="images/i_165.jpg" alt="...from which next spring the Moths will come" /></div> <p>Scientists call her by a name as long as she is tiny. Part of the name is Microgaster. It is what I shall have to call her, for she has no other that I know of. You must blame the wise scientists who named her that, and not me.</p> <p>How does she work? Well, we shall see. In the <SPAN name="page-166" class="pagenum" href="#page-166" title="166"></SPAN> spring, let us look about our kitchen-gardens. We can hardly help noticing against the walls or on the withered grasses at the foot of the hedges some very small yellow cocoons, heaped into masses the size of a hazel-nut. Beside each group lies a Cabbage-caterpillar, sometimes dead and always looking very tattered. These cocoons are the work of the Microgaster’s family, hatched or on the point of hatching; they have been feeding on the poor Caterpillar.</p> <p>The little Microgaster or Midge is about the size of a Gnat. When the Caterpillar-moth lays her orange eggs on the cabbage leaves, the Midge hastens up and with a slender, horny prickle she possesses, lays her egg <em>inside</em> the film of the Moth’s egg. Often many Midges lay their little eggs in the same Moth’s egg. Judging by the cocoons, there are sometimes as many as sixty-five Midges to one Caterpillar.</p> <p>As the Caterpillar grows up, it does not seem to suffer; it feeds on the cabbage leaves and, when that is done, makes its pilgrimage as usual to find the place where it will weave its cocoon. It even begins this work; but it is listless, it has no strength; it grows thin and dies. No wonder, with a host of worms of the little Microgaster in its body, drinking its blood! The Caterpillar has obligingly lived till just the time when the Microgaster’s worms are ready to come out. They do so, and begin to weave their cocoons, where they turn into Midges with the long name.</p> <div><SPAN name="page-167" class="pagenum" href="#page-167" title="167"></SPAN></div> <div style="break-after:column;"></div><br />