David R. Britton
davidb at uow.edu.au
Mon Nov 17 17:46:29 EST 1997
In article <34704427.42EA at gate.net>, viceroy at GATE.NET wrote:
> Alas, the introduced plants are often hosts for local butterflies, and
> can cause problems by artificially elevating populations, which are then
> regarded as pests.
Yep, I guess we have one of those in Northern Queensland (a beautiful
lycaenid) which chews up people's prize cultivated orchids.
> In South Florida, rare cycads, native and exotic support unwanted
> populations of the rare atala butterfly (Eumaeus atala), which thrives
> on the nectar from such exotic trees as your earleaf acacia and
> melaleuca, and Brazil's Schinus terebinthefolius. The butterfly is a
> bit of a pest in nurseries and botanical gardens, although indeed we
> love it.
There are a number of interesting range expansions which have occurred
because of this (Cephrenes skippers on ornamental palms, Hasora khoda,
another skipper has moved from a native leguminous vine onto introduced
Wisteria, a species of Lepotes which is moving south on introduced
Plumbago, various swallowtails that have moved from native Rutaceae or
Lauraceae onto introduced species in those plant families) Also quite a
few "every day" nymphalids on introduced daisies, nettles and others. We
have the Monarch and Cabbage White (Pieris rapae) as introduced species,
but both of these feed mainly on introduced plants, so do not affect the
native ecosystems to any great extent.
I guess there are quite a few!
> Leguminous trees and shrubs from anywhere will feed many local sulphur
> and blue butterflies. Any brassica is likely to feed any white
> butterfly, although cabbage whites profit at the expense of picky
I'm trying to think of a case here where rarer species have been
competitively excluded by more common species of butterfly, but none
springs to mind.
> Garden ruellias feed buckeyes, malachites and white peacocks.
> It raises interesting problems in butterfly-gardening circles, where we
> find ourselves planting butterfly-attracting plants in spite of warnings
> from local exotic-pest-plant-council people that these plants are
> damaging to the environment.
> Buddleia is eating Ireland, with the happy help of rhododendron.
> Lantana, a horribly poisonous weed, gallops across Florida's pastures,
> along with other weeds which were imported, with the blessing of the
> USDA, for erosion control, green manure and so forth.
Urrgghhh. Lantana. Even if it is a great plant to find adults feeding
at, it is a horrendous weed. There is a lycaenid in South Africa whose
larvae even feed on it for part of their life-history! Is there any
butterfly whose larvae feed on Buddleia?
> Butterflies profit from any sort of change, following the bulldozer and
> enjoying new plants offered to them. But the butterflies you wind up
> with may not be the rare ones we treasure.
> I don't know what to do about the pantropical weeds we're
> planting here. Cassia bicapsularis, Scarlet milkweed, Salvia coccinea,
> blue porterweed ... butterfly host plants and great nectar plants. But
> should we be planting them?
BTW, there are sterile cultivars of Lantana which avoid the problem of
spreading seeds via birds, and still allow you to have it in the garden.
Is there any chance that you could obtain sterile varieties of these
butterfly plants to avoid any risk of being a source of noxious weeds?
> Here and in Australia, and in Hawaii ... all our islands are
> irretrievably contaminated. So do we struggle, or do we relax and enjoy
> Anne Kilmer
> South Florida
I think there is a definite case here for damage control; there is no
chance we will ever get rid of all the introduced weeds, but at least we
can try and tighten up quarantine restrictions for the nursery industry
and work on controlling and reducing the number of weeds already present
in native habitats. All the same, I think I would always have a buddleia
and a few other non-natives in my garden as attractors.
David R. Britton, Biological Sciences, University of Wollongong
Wollongong, NSW, Australia, 2522.
Ph.(61-2) 4221 3436,Fax.(61-2) 4221 4135
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