. Economic entomology for the STRUCTURE AXD CLASSIFICATION. peared entirely, and all the other structures have been so modi- fied that nothing remains except this flexible sucking tube. I use the term "tube," although it is not such in reality, being made up of two hollow crescents, more or less firmly held to- gether, so that, practically, it serves all the purposes of a complete tube. When the insect feeds the tongue is extended, the muscu- lar structure being accommodated in the walls of each half of the tube. Fig. 4 illustrates a section through a butterfly tongue, show
. Economic entomology for the STRUCTURE AXD CLASSIFICATION. peared entirely, and all the other structures have been so modi- fied that nothing remains except this flexible sucking tube. I use the term "tube," although it is not such in reality, being made up of two hollow crescents, more or less firmly held to- gether, so that, practically, it serves all the purposes of a complete tube. When the insect feeds the tongue is extended, the muscu- lar structure being accommodated in the walls of each half of the tube. Fig. 4 illustrates a section through a butterfly tongue, showing the way in which the two parts are united. At its tip there are often more or less devel- oped processes which serve as taste cups, and also to assist in gathering up the minute globules of nectar. A tongue of this description indicates a type which can never be harmful to vege- tation, because it is not fitted for either piercing or eating plant tissue ; but it is, on the contrary, of direct use in pollenizing flowers. Butterflies and moths are never injurious in the adult stage, however much their larvae may offend ; but many are especially adapted for pollenizing certain flowers. Thus the " Hawk-moths," with tongues five and six inches in length, are able to reach to the very base of flowers like the petunias, even- ing primrose, " Jimpson weed," and many orchids. A widely different type of sucking mouth is found among the "bugs," or Heiniptera. Here, instead of a flexible tube, there is a jointed, rigid beak or rostrum, made up of either three or four segments, inside of which run four pointed lancets. This beak is not a complete tube, but narrowly open in front and at the tip, to permit the protrusion of the lancets. Insects with this structure gain their food by piercing the plant tissue and sucking the juices, and such a structure always leaves its possessor open to the suspicion of being injurious. As a matter of fact, many of the Hemip
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Keywords: ., bo, bookcentury1800, bookdecade1890, bookpublishernp, bookyear1896
