Ce manuel sert de guide pour l'étude des insectes, offrant des techniques d'identification et de gestion des populations d'insectes. Il fournit des instructions sur la lutte contre les insectes nuisibles et la protection des cultures contre les dommages, en particulier par des méthodes mécaniques telles que le creusement de fossés et la pulvérisation.
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. A manual for the study of insects. Insects. 304 THE STUDY OF INSECTS, . If it is discovered before it has spread from these places it can be confined by surrounding the field with a ditch, or it may be destroyed by spraying the grass with Paris-green water. Ordinarily, however, the vi^orms are not observed until after they have begun to march and are wide-spread. In such cases it is customary to protect fields of grain in their path by surrounding them with ditches with ver- tical sides; it is w^ell to dig ¥G.j, (>T.—Leucaniaunij>zi7icta. holcs like post-holcs at in- tervals of a few rods in the bottom of such ditches. The worms falling into the ditch are unable to get out, and crawl along at the bottom and fall into these deeper holes. We have seen these insects collected by the bushel in this way. The Diver, Bellura gortynides (Bel-lu'ra gor-tyn^i-des).— One of the most remarkable exceptions to what are usually the habits of members of this order is presented by the larva of this species. This larva is able to descend into water and remain there for a long time. It lives in the leaf- stalks of the pond-lily. It bores a hole from the upper side of the leaf into the petiole, which it tunnels in some instances to the depth of two feet or more below the surface of the water. This necessitates its remaining below the surface of the water while feeding. The writer has seen one of these larvae remain under water ^'g- 368.-^5^//^^^^ gortynides. voluntarily for the space of a half-hour. The tracheae of these larvae are unusually large, and we believe that they serve as reservoirs of air for the use of the insect while under water. The form of the hind end of the larva has also been modi-. 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 work.. Comstock, John Henry, 1849-1931; Comstock, Anna Botsford
