Entomology : with special reference to its biological and economic aspects . rvas.—The prevalent type of larva amongholometabulons insects is the cniciform (Fig. 210, E-I), illus-trated by a caterpillar or a maggot. Here the body is cylin-drical and often fleshy; the integnment weak; the legs, anten-nae, cerci, and mouth parts reduced, often to disappearance;the habits sedentary and the sense organs correspondingly re-duced. These characteristics are interpreted as being results ofpartial or entire disuse, the amount of reduction being propor-tional to the degree of inactivity. Extreme reducti
Entomology : with special reference to its biological and economic aspects . rvas.—The prevalent type of larva amongholometabulons insects is the cniciform (Fig. 210, E-I), illus-trated by a caterpillar or a maggot. Here the body is cylin-drical and often fleshy; the integnment weak; the legs, anten-nae, cerci, and mouth parts reduced, often to disappearance;the habits sedentary and the sense organs correspondingly re-duced. These characteristics are interpreted as being results ofpartial or entire disuse, the amount of reduction being propor-tional to the degree of inactivity. Extreme reduction is seenin the maggots of parasitic and such other Diptera as, secur-ing their food with almost no exertion, are simple in form,thin-skinned, legless, with only a mere vestige of a head andwith sensory powers of but the simplest kind. Transitional Forms.—The eruciform is clearly derivedfrom the thysanuriform type, as Brauer and Packard haveshown, the continuity between the two types being establishedby means of a complete series of intermediate stages. The Fig.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
