Genus ORETA Walker (1) Oreta rosea Walker, Plate XLI, Fig. 24, 9. Syn. americana Herrich-Schæffer; formula Grote. The moth is a native of the eastern portions of our territory. (2) Oreta irrorata Packard, Plate XLI, Fig. 6, 9. The range of this species is coincident with that of the last. Genus DREPANA Schrank (1) Drepana arcuata Walker, Plate XLI, Fig. 23, 8. Syn. fabula Grote. Form genicula Grote, Plate XLI, Fig. 22, 8. The species, which is dimorphic, inhabits the Appalachian subregion. The form genicula occurs in the spring, the form arcuata in the summer. Genus FALCARIA Haworth The genus is common to both hemispheres. (1) Falcaria bilineata Packard, Plate XLI, Fig. 7, 9. The insect, which is by no means common, is a native of the eastern portion of our territory. TRANSFORMATION 'Who that beholds the summer's glistering swarms, Ten thousand thousand gaily gilded forms, In volant dance of mix'd rotation play, Bask in the beam, and beautify the day; Or who with transient view, beholding, loaths Those crawling sects, whom vilest semblance cloaths; As by contempt, or negligence of fate; Could think, that such, revers'd by wondrous doom, Sublimer powers and brighter forms assume; From death their future happier life derive, And tho' apparently entomb'd, revive; HENRY BROOKE. -Universal Beauty. FAMILY GEOMETRIDÆ . . . The sylvan powers Obey our summons; from their deepest dells Or rifted oak or cavern deep: the Naiads too J. TAYLOR.-Norwich, 1818. The Geometrida are a very large and universally distributed family of moths. There is no country where there is any vegetation where they do not occur. Even in the inhospitable regions of the far North, upon the verge of the eternal ice, they may be found. They are more or less frail in their habit, with considerable expanse of wing in proportion to the size of the body. They are semidiurnal or crepuscular. They have been characterized as follows by Sir George F. Hampson: "... Proboscis present or rarely absent. Legs and tarsi slender, elongate, and naked, or slightly clothed with hair. Fore wing with vein 1a forming a fork with 1b. Ic absent; vein 5 from or from above middle of the discocellulars, 7 rising from 8, 9. Hind wing with the frenulum usually present, but absent in a few genera. Vein 1a very short, apparently absent in some forms; vein 1b running to anal angle; ic absent. 8 with a welldeveloped precostal spur. Larva with the three anterior pairs of abdominal claspers totally aborted, and progressing by bringing the posterior somites close to the thoracic, looping the medial somites. In a few ancestral forms there is tendency to develop additional prolegs and to a more ordinary mode of progression." The larvæ, which are commonly known as "measuringworms," "span-worms," or "loopers," have the power in many cases of attaching themselves by the posterior claspers to the stems and branches of plants, and extending the remainder of the body outwardly at an angle to the growth upon which they are resting, in which attitude they wonderfully resemble short twigs. Dichromatism is often revealed among them, part of a brood of caterpillars being green and the remainder brown or yellowish. Various explanations of this phenomenon have been suggested. In not a few cases the females are wingless. Over eight hundred species of Geometrida are known to occur within the limits of the United States and Canada, and when the region shall have been exhaustively explored, there is little doubt that this number will be greatly increased. It is impossible within the limits of this book to mention and depict all of these species. We have therefore confined ourselves to the description through our plates of one hundred and seventy species, which are either more commonly encountered, or are possessed of some striking character. Incidentally occasion has been taken to figure a few of the types of species in the collection of the author which have never before been delineated. The student who desires to familiarize himself with the family with which we are now dealing will derive much assistance from the writings of Packard and Hulst, the titles of which he will find in the portion of the Introduction of this book devoted to the literature of the subject. SUBFAMILY DYSPTERIDINÆ Genus DYSPTERIS Hübner (1) Dyspteris abortivaria Herrich-Schæffer, Plate XLII, Fig. 21, 8. (The Bad-wing.) This pretty little moth may be easily recognized by the fact that the hind wings are so much smaller than the fore wings. It is the only species of the genus found within our territory. It is not uncommon in the Appalachian subregion. Genus NYCTOBIA Hulst Three species belong to this genus. One of them is selected for illustration. (1) Nyctobia limitata Walker, Plate XLII, Fig. 22, 8. Syn. lobophorata Walker; vernata Packard. The habitat of this moth is identical with that of the last-mentioned species. It is not at all uncommon in Pennsylvania. Genus CLADORA Hulst (1) Cladora atroliturata Walker, Plate XLII, Fig. 23, 8. (The Scribbler.) Syn. geminata Grote & Robinson. A neatly marked species, which is the sole representative of the genus in our fauna. The moths may be found in the early spring seated upon the trunks of trees in the forest. It is a native of the Appalachian subregion. Genus RACHELA Hulst Four species of this genus have been characterized by the late Dr. Hulst. The only one which occurs in the eastern portions of the continent we figure. (1) Rachela bruceata Hulst, Plate XLII, Fig. 24, 8. The moth is found in the northern Atlantic States. uncommon in western Pennsylvania. SUBFAMILY HYDRIOMENINÆ Genus PALEACRITA Riley It is not There are reputed to be three species of the genus found in the United States. Only one of them, because of its economic importance, has received much attention thus far. (1) Paleacrita vernata Peck, Plate XLII, Fig. 25, 8, Fig. 26, 9. (The Spring Canker-worm.) Syn. sericeiferata Walker; autumnata Packard; merricata Dyar. There are two insects known as canker-worms. One of these, the smaller of the two, is properly named the Spring Canker-worm, because the great majority of the moths issue It has been a great pest in C from the ground in the spring. orchards, and formerly in our Eastern cities was a nuisance, not only because of the injury which it inflicted upon the foliage of shade-trees, but because of the annoying manner in which the larvæ, pendent from the branches by long threads of silk, were blown about over things and persons beneath them. It was to effect their de- magnified, natural size shown in struction that the English sparrow was b a ver FIG. 195.-Paleacrita nata. a, mature larva; b, egg, mass at side; c, enlarged segment of larva, side view; d, do., viewed dorsally. (After originally imported into this country. Riley.) The ravages of the insects upon the foliage of trees in parks and gardens have measurably decreased since this step was taken, but in the open country, especially in d the Valley of the Mississippi, the insects are still numerous enough to do much harm. to orchards. The females being apterous, the best method of preventing the multiplication of the insects upon trees is to prevent them from climbing up upon the foliage and ovipositing. A simple device, which has proved very effective, is to tie a piece of rope about the trunk of the tree which it is intended to protect, and to insert between the rope and the bark strips of tin, which, having been put into place, should be bent downwardly and outwardly, so as to form a collar with a downward flare. The insects have been found not to be inclined to pass such a barrier, and they will congregate just below it, and may there be captured and destroyed. Birds are the chief enemies of the canker-worm, and every wise orchardist will see to it that all species of insectivorous birds are not molested in his neighborhood, but are encouraged to find in his trees a hospitable welcome. The small amount of fruit which the birds take as toll is amply compensated for by the work which they perform in keeping down insect pests, such as FIG. 196.—Paleacrita vernata. a, male; b, female; c, joint of antenna; d, joint of abdomen; e, ovipositor. (After Riley.) |