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Ailanthus webworm moth
(Atteva aurea)
© Beatriz Moisset
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Somebody I know lamented that the
pretty ailanthus webworm moth (Atteva aurea), despite being
native, got the name of the tree of
heaven (Ailanthus altissima), a Chinese tree that, after being introduced as an ornamental, has become dreadfully invasive. The explanation of this state of
affairs makes perfect sense.
The ailanthus webworm moth's original
geographic range extended from Central America to southern Florida
where its larvae used to feed on several trees, related to the tree
of heaven. Probably it was known only by Lepidopterists, those who
study moths and butterflies, and not by the general public. When the
tree of heaven was introduced as an ornamental, the moth took a
liking to it and found it quite digestible. Now it was free to move
to other places, following this new host plant. With time it became
far more abundant and widespread than originally.
Nowadays it is found throughout eastern and
central United States and Canada, wherever the tree of heaven is
grown. In fact, it cannot be regarded as a native species in such
areas, but an introduced one. Political boundaries are irrelevant.
What matters is the ecological distribution.
Even more complex is the story of theColorado potato beetle (Leptinotarsa decemlineata) which is
neither from Colorado, nor a potato beetle. Originally this beetle
lived on Mexico and southern United States and fed on local plants
related to the potato.
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Colorado potato beetle
(Leptinotarsa decemlineata)
larva and adult
© Beatriz Moisset
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Buffalo bur (Solanum
rostratum)
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Flowers of potato plant
(Solanum tuberosum)
© Beatriz Moisset
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"The presence of aurea in the eastern United States and Canada and its association with Ailanthus altissima (Mill.) (Simaroubaceae) is an interesting subject to be investigated. This plant is an ornamental introduced from Asia and now considered one of the most serious weeds in the United States. It was first planted near the University of Pennsylvania, Philadelphia, in 1784 (W. Thomas, pers. comm.) and from there it spread over the entire country. Once it reached southern Texas, where presumably aurea was already present, the moth started to move north. By 1856 it had reached Georgia, as indicated by the material described by Fitch (1856: 486). Riley (1869: 151) found it common in Missouri, feeding on ailanthus. These records indicate that this showy and common moth was absent in the region before the introduction of ailanthus, and the approximately 70-year gap between the introduction of the host, to the first record of the moth by Fitch, is the time it took the plant to move south and the moth to move north."
