Monarch butterflies (Danaus plexippus L.) use a magnetic compass for navigation

Fall migratory monarch butterflies, tested for their directional responses to magnetic cues under three conditions, amagnetic, normal, and reversed magnetic fields, showed three distinct patterns. In the absence of a magnetic field, monarchs lacked directionality as a group. In the normal magnetic field, monarchs oriented to the southwest with a group pattern typical for migrants. When the horizontal component of the magnetic field was reversed, the butterflies oriented to the northeast. In contrast, nonmigratory monarchs lacked directionality in the normal magnetic field. The results are a direct demonstration of magnetic compass orientation in migratory insects.

Natal origins of migratory monarch butterflies at wintering colonies in Mexico: New isotopic evidence

Each year, millions of monarch butterflies from eastern North America migrate to overwinter in 10–13 discrete colonies located in the Oyamel forests of central Mexico. For decades efforts to track monarch migration have relied on observations and tag-recapture methods, culminating with the discovery of the wintering colonies in 1975. Monarch tag returns from Mexico, however, are few and primarily from two accessible colonies, and therefore tag-recapture techniques have not quantified natal origins or distinctiveness among monarch populations at wintering sites. Such information would be invaluable in the conservation of the monarch and its migration phenomenon since the wintering sites currently are threatened by habitat alteration. Here we show that stable hydrogen (δD) and carbon (δ13C) isotope ratios of wintering monarchs can be used to evaluate natal origins on the summer breeding range. Stable-hydrogen and carbon isotopic values of 597 wintering monarchs from 13 wintering roost sites were compared with isotopic patterns measured in individuals at natal sites across their breeding range over a single migration cycle. We determined that all monarch wintering colonies were composed of individuals originating mainly from the Midwest, United States, thereby providing evidence for a panmictic model of wintering colony composition. However, two colonies showed more northerly origins, suggesting possible priority colonies for conservation efforts.

Beautiful butterflies of the tropics, how to collect them,

Each plate accompanied by guard sheet with descriptive letterpress.

The insect book : a popular account of the bees, wasps, ants, grasshoppers, flies and other North American insects exclusive of the butterflies, moths and beetles, with full life histories, tables and bibliographies /

Bibliography.

Butterflies; their structure, changes, and life histories.

Mode of access: Internet.

The butterflies of the eastern United States and Canada, with special reference to New England /

Includes index.

The butterflies of Georgia.

This is a revision of bulletin no. 1, published as Georgia Naturalist Club. Transactions, v.1, no.I.

Butterflies and moths of Pacific Northwest forests and woodlands : rare, endangered, and management-sensitive species /

"Species identification"--Cover.

Butterflies. Vol. I-II. /

Each plate accompanied by leaf with descriptive letter-press.

A manual of british butterflies and moths /

Contiene : Vol. 1 - Vol. 2.

On a collection of butterflies.

Reprints from Annals and magazine of natural history. Proceedings of the Zoological Society of London, and Transactions of the Entomological Society of London.

Lepidoptera of the Congo, being a systematic list of the butterflies and moths collected by the American Museum of Natural History, Congo expedition, together with descriptions of some hitherto undescribed species.

Reprinted from Bulletin of the American Museum of Natural History, Vol. XLIII, art. VI, pp. 109-369.