Insect pests of farm, garden and orchard . fthe insects work; instead of pointing upward, embracing the polereadily and growing rapidly, the tip points downward, will notclimb, and almost entirely ceases growing. This appearance iscalled by growers a muffle-head. When the insect attains a * Some Insects Affecting tlie Hop-plant, L. O. Howard, Bulletin , n. Division of Entomology, U. S. Dept. Agr., p. Hydroecia immanis Grt. Family Noctuidcp. 273 274 INSECTS INJURIOUS TO THE HOP-PI>ANT length of about half an inch, or slightly less, it leaves the tip, dropsto the ground, and ente
Insect pests of farm, garden and orchard . fthe insects work; instead of pointing upward, embracing the polereadily and growing rapidly, the tip points downward, will notclimb, and almost entirely ceases growing. This appearance iscalled by growers a muffle-head. When the insect attains a * Some Insects Affecting tlie Hop-plant, L. O. Howard, Bulletin , n. Division of Entomology, U. S. Dept. Agr., p. Hydroecia immanis Grt. Family Noctuidcp. 273 274 INSECTS INJURIOUS TO THE HOP-PI>ANT length of about half an inch, or slightly less, it leaves the tip, dropsto the ground, and entering the stem at the surface of the vine,feeds upward, .nterrupting the growth of the vine and lessening itsvitality; the larva now changes color, and becomes a dirty-white,with a strong, deep reddish tint, with numerous black spots. Thelarva, now al)Out an inch in length, and still slender, ])urrows down-ward to the ])ase of the vine at its juncture with the old stock, andeating its way out, completes its growth as a subterranean worker;. Fig. 201.—Hop-plant borer {Hydroecia immanis Grt.): o, enlarged segment oflarva; h, larva; c, pupa; d, adult, natural size. (After Howard, U. Agr.) it is in this state that it is best and most widely known as the hop grub, and the ravages caused b}*it are most noted.* The larva? have mostly left the stems by the last of Juneand henceforth are mainly sap-feeders. Eating into the stemjust below the surface of the ground and just above the old root,they rapidly grow fat upon the juices of the plant. These openingsare gradually enlarged so that very often the stem is entirelysevered from the root or is so slightly attached that the plantis badly stunted and yields few, if any, hops. The larvie becomefull grown from the middle to the 20th of July and are then * Hop-insects, Dr. J. B. Smith, Bulletin No. 4, o. s., Division of Ento-mology, U. S. Dept. Agr. INSECTS INJURIOUS TO THE HOP-PLANT 275 about two inches in length, fleshy, unwieldy
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