 ... southerly direction, find a similar explanation. They may be looked upon as continuations of the autumn flights. Hibernating in the temperate belt, they are awakened and aroused upon the advent of spring, to find the Milk-weeds not yet started, and...  The Canadian Entomologist - Página 1371879Vista completa - Acerca de este libro
 | 1878 - 798 páginas
...sweets from flowers, are either attracted in quantities to trees that are covered with honey -secret ing plants, or bark lice ; or else they must migrate southward,...seen that Mr. Riley looks upon the migration of D. anhippus as something analogous to the southern movement of the birds QO the approach of winter, the... | |
 | 1880 - 674 páginas
...the females prevail. The flights almost always occur in the autumn, when the Milk-weeds ( Asclepias), upon which the larva of this butterfly feeds, have...early in the season through isolated individuals." on the approach of winter, the object in both being the preservation of the species ; in the case of... | |
 | 1880 - 316 páginas
...extend its range ; and the prevailing winds at particular seasons are of a character to assist it. There is a southward migration late in the growing...early in the season through isolated individuals. It is a notable fact that the two butterflies which most display this instinct, namely, the species in... | |
 | Samuel Hubbard Scudder - 1893 - 202 páginas
...is doublebrooded. As Riley, the first to suggest an annual migration of this butterfly, remarks: " There is a southward migration late in the growing...early in the season through isolated individuals." Another fact in support of this theory is that no one has ever found a butterfly of this species in... | |
 | Montana State University (Missoula) - 1901 - 904 páginas
...Riley first suggested these movements, when state entomologist of Missouri, in the following words: "There Is a southward migration late in the growing season, in congregated masses, and a northward disprrsion early in the season, through isolated individuals." The more evident movement Is in the... | |
 | University of Montana (System). - 1901 - 926 páginas
...Riley first suggested these movements, whsn state entomologist of Missouri, in the following words: "There is a southward migration late in the growing season, in congregated masses, and an~rthward disp:rsion early in the season, through isolated individual?." The more evident movement... | |
 | Morton John Elrod - 1906 - 224 páginas
...Riley first suggested these movements, when state entomologist of Missouri, in the following words: "There is a southward migration late in the growing season, in congregated masses, and an rthward disp rsion early in the season, through isolated individual-." The more evident movement... | |
 | 1892 - 970 páginas
...collect the evidence for this migration remarks, " There is a southward migration late in the . . . season in congregated masses, and a northward dispersion...early in the season through isolated individuals." This, I believe, expresses precisely the state of the case, though the northward movement has not been... | |
 | Academy of Science of St. Louis - 1878 - 968 páginas
...extend its range, and the prevailing winds at the particular seasons are of a character to assist it. There is a southward migration late in the growing...dispersion early in the season through isolated individuals — this dispersion keeping pace with the advance of spring toward the north. It is a notable fact... | |
| |
