GUESTS
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& PESTS
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ENUnseasonably warm weather
has ushered in this butterfl y
earlier than usual, writes
LEONARD CRONIN
88 SEPTEMBER 2019 GARDENING AUSTRALIA
F
amiliar signs of spring are
gathering in the garden. Bird
droppings move miraculously
along the leaves of our lemon
trees, while butterfl ies with handbreadth
wingspans fl utter languidly overhead.
The swallowtails are early this year,
their breeding cycle hastened by an
unusually warm winter. Our orchard
swallowtails usually emerge from their
winter cocoons in late September. This
year, however, they have already laid
their fi rst batch of eggs, and the early
instars are chomping into our citrusleaves, ignored by hungry birds unwilling
to tuck into what appears to be fresh dung.
Over the next fi ve weeks, the instars
(caterpillars) will moult and grow, turning
greener and sporting two bright red
horns that spring out when the caterpillar
is harassed, spraying a pungent, irritating
chemical over the unfortunate predator.
With a wingspan of 13cm, this is one
of our largest butterfl ies, and its brief
adult life is devoted to dispersal and
reproduction. Males often have to search
long and hard to fi nd females to mate
with, guided by wing patterns that arehidden from our eyes. Each wing bears
more than one million overlapping scales.
Some are pigmented, while others are
transparent and split the light into brilliant
iridescent patterns in the ultraviolet and
infra-red spectrum.
When a male fi nds a female, he shows
his readiness to mate by hovering close
to her and fl uttering his wings. If she
is receptive, copulation may last for an
hour or longer.
The female lays her eggs on the
leaves of plants that provide food for the
caterpillars. These include native orange PHOTOSALAMY, ISTOCK