. Economic entomology for the 320 AN ECONOMIC ENTOMOLOGY. apples and cranberries : in apples simply feeding upon the leaves in a little case, but on cranberries often becoming seriously injuri- ous by spinning up and eating the tips of the growing shoots. It also feeds on huckleberry and allied plants, and from them goes to cultivated cranberry bogs. It is there known as the '' fire- worm," and it is distinguished from Rhopobota vacciniana, another caterpillar with the same habits, by having a yellow in- stead of a black head. Both these insects have similar larval habits, but t
. Economic entomology for the 320 AN ECONOMIC ENTOMOLOGY. apples and cranberries : in apples simply feeding upon the leaves in a little case, but on cranberries often becoming seriously injuri- ous by spinning up and eating the tips of the growing shoots. It also feeds on huckleberry and allied plants, and from them goes to cultivated cranberry bogs. It is there known as the '' fire- worm," and it is distinguished from Rhopobota vacciniana, another caterpillar with the same habits, by having a yellow in- stead of a black head. Both these insects have similar larval habits, but the Rhopobota has only two broods, and hibernates in the egg stage, while the Teras has three, and hibernates as an adult. There is a curious alternation of generations in this in- sect, the summer broods being yellow or orange, while the moths that hatch in the fall and hibernate are uniformly slate-gray. Cultivated cranberry bogs are covered with water during the winter, and the moths cannot hibernate on them ; so, as they lay their eggs quite early in spring, if the bogs are kept covered until all other vegetation has started, they oviposit elsewhere, leaving the bogs free. Therefore, holding the water late, say until at least the middle of May, is usually a fairly complete pro- tection. The Rhopobota lays its eggs upon the cranberry plants late in summer. They remain unaffected by the water with which the bog is covered until spring, then hatch, and the larvae spin up the tips precisely as in the case of the Teras, the moths com- ing to maturity early in July. Eggs for a second brood are then laid, and these are some- times sufficient in number to sweep entire bogs, giving them the appearance of having been burned over, wherefore this insect has also been called * * fire- ; As against this species, late holding the water is not so effectual, because it must be kept on until sufficiently warm to induce the eggs to hatch, the young larvae dying as soon as they break
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