Linden Inchworm
a, male moth; b, wingless female; c, larva, slightly enlarged.
“These caterpillars are long and cylindrical in shape, and they usually have but two pairs of false legs, at some distance from the true front legs. In walking they first rest themselves on the forward legs and then bring up the others by curving the body into a loop or ring. The next movement is to raise the forward legs and advance them in a stride as long as the creature itself, after which the body again bends into a loop by the bringing up of [[378]]the hind legs as before. These peculiar strides give the worm the appearance of a pair of dividers getting over the ground by alternately opening and closing its two legs. You might say the creature surveys or measures the road it travels, and that is why its moth is known as the geometer-moth. The common name of inchworm applied to the caterpillar is familiar to you as referring to the caterpillar’s length.
“Further characteristics are to be noted. Clinging to the branch solely by their hind creepers, these worms remain for hours in the strangest postures, the body stiff and motionless. You will see some stretched out straight, some turned up behind, some arched in a semicircular position. Not one moves, not one shows weariness in these uncomfortable attitudes which demand an incredible amount of strength. You have witnessed the feats of those strong-armed acrobats who, in the side-show at the fair, seize a vertical bar with both hands and without further support sustain themselves in the air, the body horizontal. Inchworms do the same thing, but with this difference: whereas the acrobats are exhausted in a few moments, the caterpillars keep their balance all day if necessary.”
“Why do they do all those stunts?” was Emile’s question.
“They are not doing stunts, as you call it; they are simply using their natural means of escaping observation on the part of their enemies. By reason of their complete immobility, rigid posture, and [[379]]grayish hue they are confounded with the small dry twigs which they closely resemble. Unless examined at very short range they deceive all eyes, even those of birds, whose sight is so keen.”
“Ah, the crafty rogues! To stiffen themselves and stay perfectly still so as to look like little dry twigs and in that way fool the birds that would come and snap them up, is a very clever trick.”
“The name of leaf-stripper, which is also given to this moth, indicates its way of living before it is transformed into the perfect insect. The caterpillar gnaws the leaves of all fruit-trees without distinction, and even of other trees, such as oaks, birches, and lindens. For trees that have not been smeared with a tar girdle to stop the moths at laying time there is but one mode of defense left, and that is not nearly so good as the first: it is to shake the infested trees so as to make the caterpillars fall, and then crush them.”
“I prefer the tar girdle,” said Louis.
“Yes, but it must be applied in time, in the autumn when the moths are about to make their appearance.