Plusia eriosoma Doubleday, 1843, in Dieffenbach, Trav. New
Zealand 2: 285.
Plusia verticillata Guenée,
1852, Hist. nat. Insectes, Spec. gen. Lepid. 6: 344.
Chrysodeixis eriosoma Doubleday;
Holloway, 1976: 32, 1977: 81.
Diagnosis. Of all the Bornean species with a ‘u’ and dot maculation on the
forewing, this and the next species are the only ones with a coppery bronze area
posterior to the maculation as well as a more pronounced dark spot in the centre
of the marginal fringe. C. illuminata Robinson has a lighter golden tone
to the narrower forewing, a diffuse dark spot at the margin adjacent to the
fringe spot and a more distinct, more angled subapical dark shade; the terminal
tuft to the abdomen is more prominent, darker.
C.acuta Walker (below) is another widespread Indo-Australian tropical species
that may prove to occur in Borneo, though no Bornean specimens have been
located. It is very similar to eriosoma but slightly smaller with a
somewhat more acute forewing apex that is almost bisected by a diffuse pale grey
streak; the latter is subparallel to the margin in eriosoma. The male
abdomen in eriosoma has lateral rufous tufts and a terminal dark one,
whereas acuta has dark brown lateral tufts only. The valves of the male
genitalia expand to the apex in acuta but taper in eriosoma; there
is a row of small cornuti in the aedeagus vesica of acuta rather than
distinct small and large groups.
Taxonomic note. The distinction from the African/European C. chalcites Esper has
yet to be clarified satisfactorily. The biology of the two species is very
similar and both are migratory.
Geographical range. Southern Asia, and through the Indo-Australian
tropics to New Zealand and Polynesia; migratory. The distribution is mapped in
the Commonwealth Institute of Entomology Distribution Map of Pests 376.
Habitat preference. The species in most abundant in agricultural areas
and open habitats in the lowlands and foothills but has been taken from
altitudes up to 2600m. Such individuals may be hill-topping.
Biology. The general characteristics of the larva are given in the introduction
to the subfamily and detailed by Gardner (1947) and Ichinose ( 1962, 1973). The
species is polyphagous on a wide range of plant families and a pest of crops in
the Solanaceae, Leguminosae, Cruciferae and Malvaceae.
The species is migratory and indulges in hill-topping behaviour as an
adult, phenomena that may be correlated (Holloway, 1977).
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