Pachysphinx occidentalis
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Pachysphinx occidentalis , specimen |
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| Pachysphinx occidentalis | ||||||||||||
| ( Edwards , 1875) |
Pachysphinx occidentalis is a butterfly ( moth ) from the family of the swarmers (Sphingidae). The species formsmixed forms or natural hybridswith Pachysphinx modesta in the Rocky Mountains, the taxonomic position of which has not yet been fully explored.
features
butterfly
The moths have a fore wing length of 51 to 71 millimeters. With a wingspan of more than 165 millimeters in females, the species is one of the largest swarming species in North America. They are similar to the somewhat smaller Pachysphinx modesta . Both species have wavy outer edges on the forewings, a contrasting dark color on the medial area of the forewings and reddish hindwings with a striking blue markings in the anal angle. The basic color of Pachysphinx modesta is more mouse gray, whereas Pachysphinx occidentalis is much lighter yellowish brown. The blue markings on the hind wings of Pachysphinx modesta are partially covered by a black triangle. In Pachysphinx occidentalis this pattern is much lighter and divided by two black lines. The pattern of the moths is hardly variable. The moths from Arizona, Nevada and California in particular have a largely uniform pattern. However, there are two color forms that also appear together in the same place. The typical yellowish-brown shape is accompanied by a darker shape with a high proportion of gray scales.
Caterpillar
The caterpillars of Pachysphinx occidentalis can be distinguished from those of Pachysphinx modesta by two fairly uniform characteristics. In the last stage, the caterpillars of Pachysphinx occidentalis lack the small, white setae that are present in the similar species. In addition, the anal horn of Pachysphinx occidentalis is at least twice as long as that of Pachysphinx modesta .
Doll
The pupa is chestnut brown to almost black and relatively large. She has a granular surface and fused with the body proboscis . The cremaster is shorter than that of Pachysphinx modesta , but also has a single, broad, blunt tip.
egg
The eggs are greyish green with a distinct pink cast at the beginning. They are relatively large, round and somewhat flattened.
Occurrence
The species is distributed from west Texas along the Mexican border to southern California and north along the Pacific coast to at least east Washington. In the Rocky Mountains, in addition to individuals clearly identifiable as Pachysphinx occidentalis , there are also mixed forms with Pachysphinx modesta . The exact delimitation of the distribution area in the overlap zone to the east and north is difficult. In the north, Pachysphinx occidentalis apparently still occurs at least in the southeast of Alberta and southwest of Saskatchewan in Canada, and in the east there doesn't seem to be any reliable evidence east of the Mississippi River.
Like Pachysphinx modesta, the animals are strongly tied to willow plants. In the drier south-west and west they are therefore limited to the banks of waters in lower elevations or in higher elevations on meadows.
Way of life
Little is known about the way animals live. Whether the Imagines nectar can take is unknown, probably their mouthparts are atrophied. Most of the moths fly in one generation per year in most of their range, but a second generation could occur in Arizona. There the species flies mainly in the rainy season in July and August, but there are also a few records from April and May.
Food of the caterpillars
The caterpillars have been found on Populus Fremontii in southern Arizona . Further evidence comes from willows ( Salix ), such as Salix bonplaudiana .
development
The females lay their eggs in small groups of three to ten on either side of the leaves of the host plants. Very many of them, up to 90%, fall victim to parasitoids . After about a week, the caterpillars hatch and often first eat the eggshell. Shortly after hatching, the caterpillars spread out and live as solitary animals. Pupation takes place in a chamber that is quite deep in the ground.
supporting documents
Individual evidence
- ↑ a b c d e f g h i j James P. Tuttle: The Hawkmoths of North America, A Natural History Study of the Sphingidae of the United States and Canada. The Wedge Entomological Research Foundation, Washington, DC 2007, ISBN 978-0-9796633-0-7 , pp. 127f.
literature
- James P. Tuttle: The Hawkmoths of North America, A Natural History Study of the Sphingidae of the United States and Canada. The Wedge Entomological Research Foundation, Washington, DC 2007, ISBN 978-0-9796633-0-7 .
