. Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges;. Insects; Pests. i8 yljV ECONOMIC ENTOMOLOGY. a rule, they will bear close watching. One thing is certain, how- ever : no insect with this type of mouth structure can be reached by means of a stomach poison. Destruction through its food is, therefore, absolutely impossi- ble, because we cannot poison the plant juices by any method thus far at our command. An insect of this kind is incapable of eating any solid food what- ever, and no matter how thor- oughly covered with a
. Economic entomology for the farmer and the fruit grower, and for use as a text-book in agricultural schools and colleges;. Insects; Pests. i8 yljV ECONOMIC ENTOMOLOGY. a rule, they will bear close watching. One thing is certain, how- ever : no insect with this type of mouth structure can be reached by means of a stomach poison. Destruction through its food is, therefore, absolutely impossi- ble, because we cannot poison the plant juices by any method thus far at our command. An insect of this kind is incapable of eating any solid food what- ever, and no matter how thor- oughly covered with a corro- sive poison the outside of our plants may be, it would 'get none, since it only punctures the tissue without absorbing any portion of the outer sur- face. Thus the determination of the type of mouth structure often limits or decides the char- acter of the remedy to be used M i> \1F/ J9 I ^" destroying the insect. A '3lJwL^ I Among the Z'/^/ffra, or flies, we have a number of interest- the ing modifications of the suck- One series is fur- to those in the bugs, but more numerous, representing different mouth structures, and not always carried into the head itself The sucking structure is also quite different, and never forms a rigid, jointed beak. Mosquitoes and horse-flies are examples of this kind ; but gradually the lancets disappear, and in most of the flies only the sucking lip, often greatly and interestingly developed, remains. The common house-flies and blow-flies are types of this modified form, and are capable of taking liquid food only, though often seen attacking solids. If the mouth of a fly be examined under the microscope, there will be seen at the tip of the lip a series of deep grooves, stiffened with chitinous loops, and armed with sharp projecting edges. When the fly wishes to feed on a solid, it scrapes the surface by means of these rasp-like projec-. Mouth parts of a plant-louse.—a, jointed beak ; (J, the lancets, much enlarged ; ;.,„ rnrj
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectinsects, bookyear1906
