Amyna axis
| Amyna axis | |
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| Amyna axis larvae | |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Lepidoptera |
| Family: | Erebidae |
| Subfamily: | Boletobiinae |
| Genus: | Amyna |
| Species: | A. axis |
| Binomial name | |
| Amyna axis (Guenée, 1852) | |
| Synonyms | |
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The Eight-Spot (Amyna axis) is a moth of the Erebidae family.
Distribution
It is found in the tropics and subtropics worldwide, and occurs in Africa, India, Indonesia. Australia and the Cook Islands.[1]
The moth migrates north each year in late summer and fall. It is common in southern North America, from Florida to Arizona. It is a regular migrant to the mid-eastern states, and rarely as far as Wisconsin, Ontario and Quebec.
Adults are on wing from August to October.
Life cycle
Food plants
The larvae feed on Amaranthus, Croton, Celosia, Digera, Helianthus, Chenopodium, Spinacia, Ipomoea, Ricinus, Arachis, Crotalaria, Medicago, Phaseolus, Hibiscus, Cardiospermum, Solanum, Corchorus and Parasponia species.[2]
It is an irregular minor pest worldwide of mung beans (Vigna radiata), black-eyed peas (Vigna unguiclata), lucerne (Medicago sativa) and soy beans (Glycine max). Their prevalence may be under-reported due to the resemblance of the caterpillar with those of Chrysoieixis species.[1]
Early stages
The larva are thin-bodied have faint white stripes and two pairs of ventral pro-legs.[1] At low densities caterpillars are pale green. Among caterpillars at high densities there are higher frequencies of melanistic phenotypes. The degree of blackening varied widely, ranging from individuals with simple subdorsal-lateral patches to those that were mostly black.[2]
Larvae perch on the undersides of leaves and along stems and petioles. At rest, the abdominal segments are often looped upward. When alarmed the larva essentially jumps from the host and continues to wreathe and wriggle wildly. Prepupal larvae take on a pinkish cast. Pupation occurs in a silken cocoon below (usually) or at the soil surface. Sand and/or plant debris are interwoven into the cocoon wall.[2]
Adult
The adult moth is chocolate brown above and has a wingspan of 20–25 mm. The forewings have faint greyish-white lines and an obscure figure-of-eight mark on it. The hindwings are lighter with fainter markings. The male can be differentiated by the presence of a small semi-transparent patch on each wing.[1]
Gallery
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Last instar larva:1. Chaetotaxy. SD2 on abdomen represented only by its pinaculum (forward of spiracle); 2. Head, frontal; 3. Labrum, frontal; 4. Mandibles, mesal surfaces
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Last instar larva: 5. Head, frontal; 6. Head, lateral, with prothoracic gland (adenosma) indicated; 7. Crochets, with subapical tooth indicated
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Larvae caudal segments
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Prepupa
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Pupa and cocoon
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Pupa ventral (left), lateral (right)
References
- 1 2 3 4 Bailey, Peter (2007). Pests of Field Crops and Pastures: Identification and Control. CSIRO Publishing. p. 528. ISBN 978-0-643-06758-5. Retrieved 29 April 2010.
- 1 2 3 Wagner, DL; Binns S (2010). Larva and pupa of Amyna axis (Guenée, 1852) and affirmation of its taxonomic placement in Bagisarinae (Lepidoptera, Noctuidae). ZooKeys. p. 4. ISSN 1313-2970. Retrieved 29 April 2010.
External links
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