A Strange Story of a Grasshopper
A FEW days ago, while returning from a walk, I chanced to observe a dead grasshopper upon the dirt at the side of the road. Now this incident would not have been of special importance had I not discovered, upon careful post-mortem examination, the very remarkable manner of the insect's death, which recalled a similar surprising episode of several years ago which I had almost forgotten. Upon referring to my note-book of that period, however, I found considerable space devoted to the incident, which greatly astonished me at the time. Inasmuch as it presents in a startling light the wonderful and strange resources by which nature holds in check the too rapid increase of species and maintains the great law of equilibrium among the insect forces, it is well worth recalling in these pages, in the firm belief that my young entomological readers will henceforth look more compassionately and tenderly upon the poor "high-elbowed grig" who is the unfortunate hero of my story. He is familiar to us all, that hovering "rattler" above the hot, dusty road of August, flying up from nowhere beneath our feet in the path, fluttering like a yellow moth, and always disappearing before our eyes when he alights. He is also known as the "Quaker," from his drab suit and bonnet, and his generosity with his "molasses" is proverbial from the days of the Pilgrim settlers. Who would have believed that such a fate as the following lay in store for him.
In previous papers I have indicated some of the remarkable pranks which the various ichneumon-flies play with unsuspecting caterpillars. The polyphemus, for instance, whose cocoon, filled with hopes of a beautiful butterfly existence, yields only a swarm of wasps. The caterpillars are helpless, and would seem an easy prey to the wily fly who lays her eggs upon them; but even the agile-winged "Quaker," and doubtless many of his kind—yes, and still more agile insects—are not quick enough to escape a like fate.
At the time of my discovery I had in preparation an article for "Harper's Magazine" entitled "Among Our Footprints." I wished to describe and illustrate a singular battle which I had shortly before observed between a large red mutilla ant and a "Quaker." The mutilla I had captured at the time, and had preserved as a specimen. I needed only the grasshopper to complete my drawing. Directly in front of my city house a number of vacant grassy lots offered a favorite haunt for the insects—I used to call it the Quaker camp-meeting ground—and I started out to procure one. Having no net, I was soon convinced that I was greatly at a disadvantage. The thermometer was about 90°, and, of course, the "Quakers," being in their element, had much the best, not to say the easiest, time of it. I at length gave up the chase, and was about leaving the field, when fortune favored me by the discovery of a clumsy specimen, which seemed unable to fly for any great length, and he was soon captured. Upon examination his wings seemed partially paralyzed, but otherwise he appeared to be in good health and spirits, his hind legs being especially lively and snappy. I immediately took the insect to my studio, and pinned him through the thorax. He was strong enough to pull out the pin from the board and jump around the room with it in my temporary absence.
I lost no time in taking his portrait, which figured in the illustration to the article on "Footprints" as "the ungainly victim," I little dreaming when I gave him such a title what a remarkable sort of victim he even then was. The drawing took me about ten minutes. I then left the studio, and was absent precisely fifteen minutes. Upon returning I found the grasshopper dead.
My curiosity was aroused, not only by such a rapid demise (for the impaling through the thorax is not usually an immediately fatal injury to an insect), but especially by some very strange and unnatural automatic movements of the victim—head protruding and turning from side to side; queer expansion of body, as though breathing; unusual lifting and other motions of legs, particularly of hind legs; the whole demonstration a mockery on life. The grasshopper was pinned to my drawing-board, and against a piece of newspaper. As I watched his strange antics, I suddenly discovered that he had become a veritable phantom of his former self; that I could actually read the newspaper text through his body. Examination now revealed the mystery. I could easily see every nook and cranny of the grasshopper's interior, so glassy were the walls of the body, and I could now count about a dozen small, white larvæ, which were now full grown, and were crawling about within through head, thorax, body, and hind legs, cleaning its walls of every particle of remaining tissue, and causing the singular motions described. Such a strange house-cleaning I never saw before.
When the "Quaker" locust was captured it showed not the slightest sign of any such goings-on within its being. The final voracity of the larvæ was swift and terrible. And what an astonishing instinct is that which should teach these parasites to avoid the vitals of their insect host until the last moments of their own final, complete growth! The entire space of time from the activity of the grasshopper to the empty, transparent phantom was less than thirty minutes. I placed the unfortunate victim in a small, close box. Next morning he presented nothing but a clean, glassy shell, now more glassy than before, empty of every vestige of organic matter, while scattered about on the bottom of the box lay fifteen dark red, egg-shaped chrysalides of the escaped larvæ. Two weeks later, upon opening the box, a swarm of flies flew out. I was enabled to keep two of them. They were almost exactly like the common house-fly to the ordinary observer, but belonged to a distinct genus. At this writing, in the absence of my specimen, I cannot give the name by which they are known in learned circles, but I think I am safe in saying that they probably belong to the group called Tachina, a family of parasitic flies which spend their early lives in a similar questionable manner, to the probable discomfort of potato-bugs, caterpillars, and other accommodating insect hosts.
I had seen similar flies emerging from my caterpillar boxes in my early entomological days without suspecting their significance, and any large collection of caterpillars in confinement is likely to include a victim.