Page:Popular Science Monthly Volume 29.djvu/806

786 numerous dangers; so, to avoid this, they crawl up the banks and burrow into the saturated mud or soil, and at times penetrating from the stream-bed, the earth or mud thrown out forming the mound, an opening or door is generally left at one side or on top. Water collects in the bottom of this burrow, while the upper portion is entirely free, thus enabling the cray-fish to take to the water or not, as it is inclined. These mounds are probably built when the streams rise, the crustaceans leaving the swift current and taking to the higher ground for better security. To show how a flood or over-supply of water will at certain times alarm these little creatures, a gentleman residing in Freeport, Illinois, informed me that not many months ago they had some very heavy rains, that greatly increased the volume of the little river running through the town. The water gradually rose until numbers of quite large trees were submerged, and the stream was almost twice its ordinary width. Such an unusual occurrence naturally attracted considerable attention, and my informant and a number of others visited the trees several times, and when the river was at the highest they presented a strange appearance from a little distance. Their trunks seemed to have changed color from the water up to the branches, and on closer inspection it was found that they were completely incased with cray-fish which covered every available space, crowding upward by hundreds, clinging to the bark and to each other, in some spots packed one upon another four and five deep; every moment added to the throng, new ones emerging from the water, while those above, urged on, crept out upon the branches, and completely covered them, presenting a novel and interesting sight. The animals in many cases retained their positions for several days, and did not seem to be affected by their stay out of water. The occasion, however, was taken advantage of by the people, who came with buckets and brooms and swept them from the trees by hundreds, storing them up for future use. The cray-fish in certain portions of the Western country is a pest to the agriculturist, and the work of these little creatures often greatly increases the labor and expense of breaking up land, especially after the burrows or mounds have stood for many years, the vegetation that has grown upon them often increasing their size to mammoth proportions, comparatively speaking. Some farmers consider, however, that they enrich the land by keeping it open, and in many other ways, and that land with cray-fish-heaps is worth more to the acre from this cause. To the man who plows his land in the old-fashioned way, as many Germans yet do, the cray-fish is a hindrance and a pest. Not the least remarkable feature of the life of this little creature is the fact of its living so far from open streams. In many cases examined by me, no stream or brook was present, a mere bog being the center of attraction. How they had wandered so far from clear running water was a mystery. Scientifically, the cray-fish belongs to the family Astacidæ. About fifteen different