The Germ War on Washington’s Wheat-Field Squirrels

Dr. A. F. Kibbe, bacteriologist to the state board of health, is conducting a series of experiments to determine whether it is possible to destroy the ground squirrels that have proved such a pest to farmers in Eastern Washington. He thinks it may be possible by the aid of a germ which is said to have been successful in laboratory experiments. So little is known of the ground squirrels of this state that the results are at present a matter of conjecture only. Tests of the germ are now being made on a number of squirrels recently received from Ellensburg.

As an example of the ravages produced by this animal, the farmer who furnished the squirrels stated that every vestige of vegetation had been swept from his hills and that his wheat crop was utterly destroyed. Not only are they destroyers of crops, but in many instances the very ditches that carry the water with which the farmer irrigates his land are riddled by them in their burrowing, necessitating great expense to keep the ditches in order.

This animal is about as large as a red squirrel and has bright black eyes. The ears form but a very narrow rim, raised but little above the surrounding skin. In color the animal resembles the ordinary gopher of the plains. The tail is comparatively short and lacks entirely the bushy appearance of that of the ordinary squirrel.

When Dr. Kibbe was interviewed about his experiments he said:

“While I was visiting my friend, Dr. J. E. Bingham, of Walla Walla, some two years ago, he told me some amusing stories in connection with his attempts on the life of the ground squirrel. During the conversation I first learned how destructive this small animal was to the wheat fields, in many instances farmers having lost their entire crop. As a physician, his knowledge of the various poisons was necessarily exact and exhaustive. He told me that he had tried almost everything in the list of poisons known to be fatal to man. While many of them were effective, the expense prevented their practical use. Strychnine had seemed to be the most effective as far as cost was concerned. In talking the matter over with him, I suggested the idea that, if it were possible to inoculate the animals with the germ of a disease which would spread, it would be less expensive and far more effective, for the reason that the animals themselves would act as carriers of the poison to one another.

“The first question to be determined would necessarily be to find a germ which would be fatal to the animals when taken into the stomach through the medium of food. Next, the germ must be such a one as would be harmless to domestic animals. Provided the ground squirrels were omnivorous and ate the bodies of those of their species who died from disease or injury, it would be a simple matter to inoculate them with a number of germs which would be fatal, but at the same time that this was done we might convey an infectious disease to cattle or horses, resulting in infinitely more damage than that produced by the ground squirrels. Knowing absolutely nothing about the habits of the ground squirrel and being unable to learn anything of its peculiarities as a species from those living in the country east of the mountains, I was forced to defer any experiments until I had access to a laboratory and was supplied with the necessary germs to begin a series of experiments. When the state board of health established a laboratory in this place, I was in a position to undertake the investigation of this question in a scientific way.

“In keeping with a promise made me at the time of the above-mentioned conversation, Dr. Bingham and his associate, Dr. Keylor, in response to a request, sent me by express ten ground squirrels. On the arrival of the box five of the number were dead, and of the bodies of three of them but little was left but the hide, bones and claws, the balance having been eaten away by the survivors. This fact settled the most important part of the question, for, in captivity at least, they were carnivorous. Of the remaining five two died the following day after arrival, two escaped, and I thus had only one left on which to experiment. For several weeks I devoted my time to studying the habits of the animal in captivity, finding that he would eat almost anything; meat he ate voraciously, wheat he devoured much as does a squirrel sitting up on his hind legs and holding the grain in his paws; cabbage, clover and vegetables of all kinds seemed to be agreeable to him. He has been in the laboratory now about six weeks and has never touched a drop of water to my knowledge. Water has been placed in his cage and has remained untouched for several days. That which has disappeared could be accounted for by evaporation. I recently received a dozen or more squirrels from Ellensburg which were furnished me through the kindness of Mr. G. Lindsay Campbell and the editor of the Ellensburg Capitol. These animals had been in confinement about two weeks and have not received a drop of water during that time. They have grown fat and active, in spite of that fact. It would seem to me that they derive sufficient water from the vegetation on which they live.

“Having settled to my satisfaction a number of points regarding the habits of these animals and being satisfied that those which I had were all in good health, I proceeded to look up literature on the subject of experimental inoculation of pests of various natures infecting grain fields. I found that experiments had been made in the laboratory of an experiment station in Odessa, Russia, on one species of the spermophiles, or, as they are termed, ground squirrels, with a germ which is not dangerous to any of the domestic animals as far as is known, with the exception possibly of chickens, and in the latter only when injected beneath the skin. It was found in these experiments that the particular species of ground squirrel experimented upon not only died from subcutaneous inoculation, but those who gnawed at the bodies also died within three or four days. The particular germ I brought with me from Koch’s laboratory last winter, solely by accident, not being aware at the time that it had ever been put to any use of this nature. If our spermophiles, or ground squirrels, prove to be of the same species as those experimented upon in Russia, I believe the experiment trying to infect them will be successful, but as I have no means of ascertaining what the Russian variety was, the question of success must be for time to determine.

“Should the experiment be successful and the animals prove susceptible, I shall make the experiment on a broader scale by taking a culture of this germ to some point in Eastern Washington at a time of the year when vegetation is not abundant and by placing wheat previously soaked in the culture at the openings of their burrows and allowing them to become infected. If then those killed by the germ are eaten by others the disease will spread. To what extent will depend solely on the extent to which they are carnivorous. It is said that about 90 per cent of their food is composed of insects and other low forms of life; especially is this the case late in the fall, when vegetation has to a great extent disappeared.

“At the present time I am engaged in determining whether this particular germ is fatal to the ground squirrel found in this state. This point cannot be determined positively under several weeks. At the same time it will be necessary to ascertain just what article of food is best suited to be used as a means of conveyance.”