Elementary entomology elementaryentomo00sand Year: [c1912] 20 ELEMENTARY ENTOMOLOGY We have stated that the structure of insects often determines the method of treating them. This may now be understood, for it is evident that / a poison such as Paris green, ap- plied to the food of a sucking in- sect, such as a plant-louse, would not be taken into the mouth through the sucking mouth- parts, which ex- tract only the juices beneath the sur- face, while it might be entirely effect- ive against an insect with biting mouth-parts, which consumed the sur- face covered by the poison. A better unders
Elementary entomology elementaryentomo00sand Year: [c1912] 20 ELEMENTARY ENTOMOLOGY We have stated that the structure of insects often determines the method of treating them. This may now be understood, for it is evident that / a poison such as Paris green, ap- plied to the food of a sucking in- sect, such as a plant-louse, would not be taken into the mouth through the sucking mouth- parts, which ex- tract only the juices beneath the sur- face, while it might be entirely effect- ive against an insect with biting mouth-parts, which consumed the sur- face covered by the poison. A better understanding of these simple facts of insect anatomy would save Amer- ican farmers thou- sands of dollars every year, now lost through ignorance. Thorax. The thorax is the middle region of the body, composed of the three segments back of the head, which are called the/;-<?- thorax, mesothorax, and metatJiorax respectively. As previously indicated, the differentiation of the thorax has been incidental to the development of the wings, and the structure of the thorax is determined by the development and use of the organs of locomo- tion. A pair of jointed legs is attached to each segment and f •' • .* j.' .-' \ • 7 ,///V' .-' --\---h B D FIG. 22. Mouth-parts of an ant (Myrmica rubra) A, seen from the lower side in situ; B and D, maxillae; C, labium seen from the upper side, detached ; a, mandible; t>, maxilla; c, mentum ; rf, maxillary palp; e, labial palp ; f, glossa or tongue ; g, adductor muscle of mandible ; //, abductor muscle of mandible ; /, labium ; k, gustatory organs; /, duct of salivary glands; ;«, maxillary comb; n, gular apodeme. (After Janet, from Wheeler)
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