. Elementary lessons on insects. Insects. 82 ELEMENTARY LESSONS ON INSECTS (b) The shelter tube, built in a crevice lined with silk, to the surface of which sand grains and bits of tissue may be attached, its front end opening into the bottom of the net. (c) The larva, with brown head sometimes visible in the bottom of the net, re- treating well inside when disturbed by means of a pull on its draghooks. 2. In aquaria watch the caddis- worms in portable cases drag their lumbering houses about. See them retreat inside when disturbed, and see them come out again. Some may be seen feeding on the p
. Elementary lessons on insects. Insects. 82 ELEMENTARY LESSONS ON INSECTS (b) The shelter tube, built in a crevice lined with silk, to the surface of which sand grains and bits of tissue may be attached, its front end opening into the bottom of the net. (c) The larva, with brown head sometimes visible in the bottom of the net, re- treating well inside when disturbed by means of a pull on its draghooks. 2. In aquaria watch the caddis- worms in portable cases drag their lumbering houses about. See them retreat inside when disturbed, and see them come out again. Some may be seen feeding on the plants present. 3. Pick up one of the larger cases containing an active larva, and drive the larva forward out of its case by poking a match stick into the case at the rear. Put the larva, naked, into the water and observe what a helpless creature it is when deprived of its proper shelter. 4. If you have at hand the living larvae in cases of the form shown in figure 30, or any other similar large form, drive the larvae out of one case, and put it and another larva in a dish of water with a single case, and watch them strive for the possession of that Fig. 30.—The portable cases of two species of caddis worms (from Lloyd).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Needham, James G. (James George), 1868-1956. Springfield, Ill. , Baltimore, Maryland, C. C. Thomas
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Keywords: ., bookcentury1900, bookcollecti, bookdecade1920, booksubjectinsects
