Insects and insecticidesA practical manual concerning noxious insects and the methods of preventing their injuries . Fig. 1. Chinch BugMagnified. Insects which undegro such a marked series ofchanges as those above described are said to havecomplete transformations, to distinguish them fromthose which do not undergo series of changes—thosewith incomplete transformations. Inone stage of existence—that of thechrysalis or pupa—insects of thefirst class take no food and areunable to move about. With these,also, the young or larva differsgreatly in form and appearancefrom the adult. Thus,
Insects and insecticidesA practical manual concerning noxious insects and the methods of preventing their injuries . Fig. 1. Chinch BugMagnified. Insects which undegro such a marked series ofchanges as those above described are said to havecomplete transformations, to distinguish them fromthose which do not undergo series of changes—thosewith incomplete transformations. Inone stage of existence—that of thechrysalis or pupa—insects of thefirst class take no food and areunable to move about. With these,also, the young or larva differsgreatly in form and appearancefrom the adult. Thus, caterpillarsare very unlike the butterflies andmoths into which they develop, and larval honeybees differ greatly from the adults; but with the in-sects of the second class this marked difference doesnot exist. The Chinch Bug furnishes a good illus-tration of these transformations. The adult(Fig. 1) depositseggs (Fig. 2. a, b)about the rootsof grass andgrain. Fromthese hatchyoung bugs (c)that do not dif-fer in general mform from theadults. They suck the sap from various plants of bug. 2. Chinch Bug: a, b, eggs; c, e, f, g, youngbugs, or nymphs. Magnified. BITING AND SUCKING INSECTS. 13 the grass family, gradually increasing in size, andmoulting at intervals. In a few weeks they becomenearly full grown, but instead of changing to a quietchrysalis state, they simply moult again and continuefeeding as before. In these early stages, which cor-respond to the larva and chrysalis, they are callednymphs. The older nymphs (g) are nearly as largeas the full grown bugs, differing mainly in theabsence of wings. In about a week they again moultand come forth as adult bugs. Grasshoppers, crick-ets, and all true bugs, undergo these incompletetransformations. BITING AND SUCKING INSECTS. Insects take their food in two ways: some insectsbite, others suck. The former, of which the ColoradoPotato Beetle is an example, are provided with jawsby which they can gnaw the surface of the food-plan
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Keywords: ., bookcentury1800, bookdecade1890, bookidi, booksubjectinsecticides
