Hessian Fly
(Belonging to the order of Diptera)
a, larva; b, pupa; c, infected wheat-stalk.
“For protecting a few square yards of cabbage-patch from these devourers,” he explained, “a rigorous search for worms and an incessant chase after butterflies on that particular piece of land might prove effective; but how keep watch over acres and acres, with butterflies and moths of many kinds flying all about and alighting every moment to lay their eggs? The cost of any such watchfulness would far exceed the value of the crop. And so it is in general, with all raising of farm products on a large scale: when once the enemy is in possession it is all but impossible to drive him out if we depend on our own resources, however [[344]]much we may spend in the attempt. Because of their infinite numbers the insects always have the advantage of us. But fortunately there are others fighting for us, and they wage valiant warfare against our insect foes, especially against worms and caterpillars.”
“You mean the birds?” asked Jules.
“Yes, and other equally useful helpers that you have never heard of, notwithstanding the immense service they render us. I refer to the insects belonging to the order known as hymenoptera.”
“Hymenoptera? I’ve never heard that word before.”
“And for that reason I hasten to explain its meaning to you. You are familiar with the honey-bee, the bumblebee, and the wasp. Like butterflies, they have four wings for flying; but these wings, instead of being covered with scales—those scales that come off on your hand and look like dust—are simply membranes of a transparent or gauzy appearance. Hence the name hymenoptera that is given to these insects, a Latin name that may be translated as ‘membranous-winged creatures.’ Furthermore, they have at the end of the abdomen a very fine sting which comes out of its sheath when the irritated insect seeks to defend itself by pricking the venturesome fingers that have seized it. In other species this sting is represented sometimes by a kind of saw or cutlass, sometimes by a blade, more or less long and slender, hidden in a fold of the stomach or else projecting and open to view. Well, insects [[345]]thus armed with a sting, a saw, or a blade, and having four membranous wings as fine and transparent as those of the honey-bee, the bumblebee, and the wasp, are called hymenoptera. They form an order just as butterflies and moths form the order of lepidoptera, and insects with sheaths protecting the lower pair of wings form the order of coleoptera.”
“The grasshopper,” Jules observed, “has a kind of sword on the end of its body, but it hasn’t the bee’s fine, transparent wings.”