Bubble Bugs blow their froth only when immature, and their bodies are a distillery or home-brew of sorts. No matter what the color, or viscosity or chemical properties of sap, regardless of whether it flows in liana, shrub, or vine, yet the Bug's artesian product is clear, tasteless and wholly without the possibility of being blown into bubbles. When a large drop has collected, the tip of the abdomen encloses a retort of air, inserts this in the drop and forces it out. In some way an imponderable amount of oil or dissolved wax is extruded and mixed with the drop, an invisible shellac which toughens the bubble and gives it an astounding glutinous endurance. As long as the abdominal air-pump can be extended into the atmosphere, so long does the pile of bubbles grow until the insect is deep buried, and to penetrate this is as unpleasant an achievement for small marauders as to force a cobweb entanglement. I have draped a big pile of bubbles around the beak of an insect-eating bird, and watched it shake its head and wipe its beak in evident disgust at the clinging oily films. In the north we have the bits of fine white foam which we characteristically call frog-spittle, but these tropic relatives have bigger bellows and their covering is like the interfering mass of films which emerges from the soap-bubble bowl when a pipe is thrust beneath the surface and that delicious gurgling sound produced.
The most marvelous part of the whole thing is that the undistilled well which the Bubble Bug taps would often overwhelm it in an instant, either by the burning acidity of its composition, or the rubber coating of death into which it hardens in the air. Yet with this current of lava or vitriol, our Bug does three wonderful things, it distills sweet water for its present protective cell of bubbles, it draws purest nourishment for continual energy to run its bellows and pump, and simultaneously it fills its blood and tissues with a pungent flavor, which in the future will be a safeguard against the attacks of birds and lizards. Little by little its wings swell to full spread and strength, muscles are fashioned in its hind legs, which in time will shoot it through great distances of space, and pigment of the most brilliant yellow and black forms on its wing covers. When at last it shuts down its little still and creeps forth through the filmy veil, it is immature no longer, but a brilliant frog-hopper, sitting on the most conspicuous leaves, trusting by pigmental warning to advertise its inedibility, and watchful for a mate, so that the future may hold no dearth of Bubble Bugs.
On my first tramp each season in the tropical jungle, I see the legionary army ants hastening on their way to battle, and the leaf-cutters plodding along, with chlorophyll hods over their shoulders, exactly as they did last year, and the year preceding, and probably a hundred thousand years before that. The Colony Egos of army and leaf-cutters may quite reasonably be classified according to Kingdom. The former, with carnivorous, voracious, nervous, vitally active members, seems an intangible, animal-like organism; while the stolid, vegetarian, unemotional, weather-swung Attas, resemble the flowing sap of the food on which they subsist—vegetable.
Yet, whatever the simile, the net of unconscious precedent is too closely drawn, the mesh of instinct is too fine to hope for any initiative. This was manifested by the most significant and spectacular occurrence I have ever observed in the world of insects. One year and a half ago I studied and reported upon, a nest of Ecitons or army ants.[3] Now, eighteen months later, apparently the same army appeared and made a similar nest of their own bodies, in the identical spot near the door of the outhouse, where I had found them before. Again we had to break up the temporary colony, and killed about three-quarters of the colony with various deadly chemicals.
In spite of all the tremendous slaughter, the Ecitons, in late afternoon, raided a small colony of Wasps-of-the-Painted-Nest. These little chaps construct a round, sub-leaf carton-home, as large as a golf ball, which carries out all the requirements of counter shading and of ruptive markings. The flattened, shadowed under surface was white, and most of the sloping walls dark brown, down which extended eight white lines, following the veins of the leaf overhead. The side close to the stem of the leaf, and consequently always in deep shadow, was pure white. The eaves catching high lights were black. All this marvelous merging with leaf tones went for naught when once an advance Eciton scout located the nest.
As the deadly mob approached, the wasplets themselves seemed to realize the futility of offering battle, and the entire colony of forty-four gathered in a forlorn group on a neighboring leaf, while their little castle was rifled—larvæ and pupæ torn from their cells and rushed down the stems to the chaos which was raging in Eciton's own home. The wasps could guard against optical discovery, but the blind Ecitons had senses which transcended vision, if not even scent.
Late that night, our lanterns showed the remnants of the Eciton army wandering aimlessly about, making near approach impossible, but apparently lacking any definite concerted action.
At six o'clock the following morning I started out for a swim, when at the foot of the laboratory steps I saw a swiftly-moving, broad line of army ants on safari, passing through the compound to the beach. I traced them back under the servants' quarters, through two clumps of bamboos to the outhouse. Later I followed along the column down to the river sand, through a dense mass of underbrush, through a hollow log, up the bank, back through light jungle—to the outhouse again, and on a large fallen log, a few feet beyond the spot where their nest had been, the ends of the circle actually came together! It was the most astonishing thing, and I had to verify it again and again before I could believe the evidence of my eyes. It was a strong column, six lines wide in many places, and the ants fully believed that they were on their way to a new home, for most were carrying eggs or larvæ, although many had food, including the larvæ of the Painted Nest Wasplets. For an hour at noon during heavy rain, the column weakened and almost disappeared, but when the sun returned, the lines rejoined, and the revolution of the vicious circle continued.
There were several places which made excellent points of observation, and here we watched and marveled. Careful measurement of the great circle showed a circumference of twelve hundred feet. We timed the laden Ecitons and found that they averaged two to two and three-quarter inches a second. So a given individual would complete the round in about two hours and a half. Many guests were plodding along with the ants, mostly staphylinids of which we secured five species, a brown histerid beetle, a tiny chalcid, and several Phorid flies, one of which was winged.