. Class book of economic entomology, with special reference to the economic insects of the northern United States and Canada. Beneficial insects; Insect pests; Insects; Insects. 34 ECONOMIC ENTOMOLOGY The cruciform type prevails among the holometabola. The body is cylindrical, and the legs, antennae and cerci are much reduced. Many transitional forms, however, occur, and it is believed that the cruciform type has been developed from the thysanuriform. Ecdysis or Moulting.—All larvae shed their outer skin (cuticula), at intervals to allow for growth. The number of moults varies in different ins
. Class book of economic entomology, with special reference to the economic insects of the northern United States and Canada. Beneficial insects; Insect pests; Insects; Insects. 34 ECONOMIC ENTOMOLOGY The cruciform type prevails among the holometabola. The body is cylindrical, and the legs, antennae and cerci are much reduced. Many transitional forms, however, occur, and it is believed that the cruciform type has been developed from the thysanuriform. Ecdysis or Moulting.—All larvae shed their outer skin (cuticula), at intervals to allow for growth. The number of moults varies in different insects, but is constant for the same species under the same conditions. In the Lepidoptcra the larva is known as a caterpillar, and is char- acterized by the possession of three pairs of true legs, and usually. Pig. 38.—Types of larvae, a. Grub of asparagus beetle; h, cutworm; c, cabbage root maggot; d, fall canker worm; e, maggot of honey bee; /, spring canker worm; g, false caterpillar of saw fly; h—a, b, c, nymphs of locust; i—a, b, c, d, e, nymphs of squash bug. {After various authors.) five pairs of prolegs on the abdominal segments. In the Diptera and Hymenoptera the larva is a maggot, characterized by the absence of legs. In the group of Saw-flies of the Hymenoptera, however, the larvas are caterpillar-like, possessing three pairs of true legs and often seven or more pairs of prolegs. In the Coleoptera the larva is termed a grub, and has usually but three pairs of legs (Fig. 38). Classification of Larvae.—]>schcrich classifies larva; as follows: Primary /.artcr. - Larva,' like the adult, and without provisional larval organs —Thysanura, Mallophaga, Pcdicididcr, Orllioplcra, Isoptcra, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lochhead, William, 1864-1927. Philadelphia :
Size: 2042px × 1224px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectinsects, bookyear1919
