Frequently Asked
Questions :
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Can hawkmoth
caterpillars sting with their horn ?
horn on tail of Privet Hawkmoth caterpillar
Sphinx ligustri
All Hawkmoths ( Sphingidae )
throughout the world have caterpillars that are equipped with a
horn at the tail end. In some species it is short and may be
curled like a pig's tail, while in others it can be extremely
long - almost as long as the caterpillar itself !
These horns look sharp and
dangerous but are in fact quite soft to touch. They cannot sting
and are entirely harmless. The purpose of the horns is
apparently unknown and would make a fascinating subject for a
scientific study.
Are any
caterpillars dangerous to touch ?
larva of
Drinker moth
Euthrix potatoria
( Lasiocampidae )
- its hairs can cause mild itching.
There are over half a million species of caterpillar in the world,
and most are completely harmless to touch.
Some however, particularly those in the families Megalopygidae,
Saturniidae, Lymantridae and Lasiocampidae have hairs or spines
which can irritate or sting. In Europe the most well known example the Brown-tail moth Euproctis
chrysorrhoea. The larval webs of this moth are commonly
found on hawthorn and bramble, particularly in coastal areas of
southern England. The caterpillars shed their hairs easily, and
if these become airborne and find their way into human eyes they
can cause painful inflammation.
Automeris liberia
( Saturniidae ), Peru - its spines can deliver a painful sting.
There are also many species of Saturniidae e.g. Automeris
liberia whose caterpillars are adorned with dozens of
stinging spines, each shaped like a miniature Xmas tree. In most
cases the sting is no worse than that of a nettle plant, but in
at
least one species it can be lethal :
The well camouflaged spiked
caterpillars of Lonomia obliqua are
often found clustered in groups of
up to 100 on the trunks of trees in Amazonia. There have been
many incidents where people have
unwittingly touched
or rubbed
their arm against groups of these caterpillars that
were
gathered on tree trunks. The effects
of a dose from multiple caterpillars can be
very severe, including massive intercranial
haemorrhaging and
kidney failure.
Lonomia obliqua caterpillars are a frequent
cause of death in southern Brazil - 354 people died between 1989
and 2005. The fatality rate is about 1.7% - roughly equivalent
to that of rattlesnake bites.
If in doubt keep well away from spiky caterpillars!
Do
some moths have feathers instead of wings ?
Many-plumed moth
Alucita hexadactyla, England
In a manner of speaking, yes.
Most moths
have 2 pairs of overlapping wings, each comprised of a very thin
double membrane with rigidity supplied by a network of tubular
veins that radiate from the base of the wings.
The
Plume moths ( Pterophorinae ) and Many-plumed moths (
Alucitidae ) however have no wing membranes.
Instead their fore and hind wings each consist of feathery
plumes - rigid spines from which branch dozens of long thin
plume-like scales.
There are 186 known species of Alucitidae worldwide, many of
which have only been discovered in the last 20 years. The name
of the moth illustrated above, hexadactyla
translates as "20 fingers" and is a misnomer as the moth
actually has 24 "feathers", although some are hidden from view.
Which
layer of the rainforest do butterflies live in ?
Butterflies
live at all layers in the rainforest. Some
species never fly
more than about a foot above the ground. Others live
permanently at the top of the tallest trees. A myriad of
other species live in the various layers in between. There
are also many species which normally live in the tree tops but
sometimes come down to ground level
at "light gaps" where sunlight penetrates to
the forest floor.
Why do
male butterflies emerge before females ?
In species
which overwinter as adults, e.g. the
Brimstone, it is noticeable that males awaken from
hibernation about 2 or 3 weeks before the first females appear.
The probable reason is that prior to copulation the females are
very sedentary - it would be wasteful for them to fly until
after they have mated, and would expose them to the risk of
predation unnecessarily. Males on the other hand need a few days
beforehand to feed up on flower nectar and build up their food
reserves, giving them the energy to enable them to fly all day
in search of potential mates.
In species that
emerge from the chrysalis in spring and summer, e.g. the
Swallowtail, the males emerge on average about a week before
the females. The reason for this is that females lose their
attraction to males very quickly, probably because the strength
of their pheromones diminishes with passing time. Consequently
they must mate within a day or two of emergence, so nature
ensures that there are plenty of males already available for the
females when they emerge.
Why do
butterflies gather at sandbanks and mud ?
Butterflies seen on sandbanks or imbibing moisture from muddy
patches are almost always males. They home in on sources of sodium
and nitrates which are found dissolved in mud or damp sand. This
process is commonly called "mud-puddling". Sodium is vital for
physiological functions including digestion, reproduction and
flight. Urine-soaked ground, carnivore dung and bird droppings are
especially rich in these minerals, and can attract large
aggregations of males. Males usually mate with more than one
female, so after mating they need to puddle again to replenish
lost salts.
Typically just one or two males
will chance upon a suitable
feeding spot, but other butterflies flying past
seem able to recognise their brethren on the ground, and swoop
down to join them. The bright patch of colourful butterflies
quickly becomes a magnet to every passing male of the same
species.
Females do not normally "mud-puddle", they feed instead on nectar,
fallen fruit and other organic matter. They obtain their sodium in
a different way - it is passed to them along with spermatophore,
by the males during copulation. Females therefore do not need to
waste valuable time puddling, and can instead concentrate on
searching for good oviposition sites.
Phoebis
argante and Rhabdodryas trite.
Males aggregating at Rio Shima, Satipo, Peru
Protesilaus earis, Madre de Dios, Peru
How long
ago did butterflies evolve ?
Estimates of the age of the earliest
insect fossils date back to at least 300 million years ago ( MYA
). The earliest Lepidoptera ( butterflies, moths and skippers
) are generally supposed to have evolved from the Trichoptera (
caddis flies ) somewhere in the region of 140-200 MYA, at roughly
the same time as the appearance of the first flowering plants.
At one
time, the land masses of the Earth were divided into 4
continents - Laurentia, Baltica, Siberia and Gondwanaland. They
gradually converged, and about 350 MYA became linked to form the
super-continent Pangaea.
It seems probable that butterflies and other insects first
appeared on Pangaea, which then began to break up about 130 MYA,
ultimately forming the present day continents. This may partly
explain why all the butterfly families are represented on more
than one continent.
More information
on this subject can be found in the
Evolution section.
Prodryas persephone (
Nymphalidae ) SCUDDER, 1878.
This is one of a dozen species of butterfly found in the
Florissant fossil beds, Colorado, USA. It dates from
the Oligocene period, 30 million years ago.
Image supplied.
How high
can butterflies fly ?
The highest flying
butterfly known is the Satyrine Paralasa
nepalica, discovered by
PAULUS in
1983. The butterfly is found at altitudes as high as 4500m (
14800 ft )
in Shey Phoksundo national park in Nepal. Another
butterfly, the Uncompahgre Fritillary
Boloria improba acrocnema, spends its entire lifecycle at
altitudes between 4000-4200m in the San Juan mountains of
Colorado, USA, although other subspecies breed at lower
altitudes in Canada and Fennoscandia. Perhaps even more amazing
however is the common Painted Lady Vanessa
cardui which is found in almost every region of the world
in habitats encompassing deserts, rainforests, prairies and
tundra - and has been recorded at altitudes everywhere between
sea level and 4000m !
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Paralasa nepalica ( Satyrinae )
PAULUS, 1983. |
What are
frass-chains ?
Frass chains are constructed
by many caterpillars, chiefly neotropical and Afro-Asian
Nymphalidae. When not feeding, the young larvae rest at the
tip of a chain constructed from their own droppings. The larva
typically eats away the leaf tissue, leaving only the midrib
intact, and then deposits a row of its droppings along the
midrib. The droppings are bound together with silk. The line
or "chain" of droppings ( = frass ) is then extended so it
projects by about 2 centimetres beyond the leaf tip.
The theory ( unproven as far
as I know ) is that it is a defence strategy to protect tiny
larvae from marauding ants – observations by Phil DeVries for
example indicate that ants are unwilling to walk out on the
"tight-rope" to attack larvae. This may be because they cannot
grip it properly to walk on, or possibly because the frass
contains a toxin that deters them. The latter might also
explain why larvae of many micro moths "camouflage" themselves
with their droppings ( rather than decorating themselves with
fragments of leaves ).
Where did the word "Emperor"
originate ?
In the British colonial era
most butterfly collecting ( particularly in the tropics ) was
undertaken by army officers, who invented English names for
their captures. It became traditional to name the larger and
more spectacular species after service ranks or sovereign
titles. Hence there are moths such as the Golden Emperor, and
butterflies such as the Archduke, Monarch, Commodore, Black
Prince, Commander, Chocolate Soldier, Tawny Rajah, Baron,
Lance Sergeant and Palm King.
The Purple Emperor butterfly
however was named by Moses Harris in 1766. The reason for its
name was probably simply a reference to it's magnificence - it
is one of the largest and most highly prized butterflies in
Europe. The name could also be connected to the fact that the
male Purple Emperors habitually perch on clumps of leaves,
known commonly as "thrones" at the top of high oak trees. They
use these perches as lookout posts from which to sight and
intercept females. It is common to see groups of males engaged
in aerial dog-fights, competing for the best "throne"
position.
Purple Emperor Apatura iris, male,
Hampshire, England
Why do some butterflies have
hairy eyes ?
All butterflies in the genus
Lethe ( Satyrinae ) have a dense
layer of fine bristles or "hairs" on their compound eyes. I can
find no published studies on the subject, so the following is
speculative :
My
observations of various Lethe species in Sri Lanka, Borneo and
West Malaysia indicate that the adults are strongly attracted to
wet dung, and spend long periods probing into it, at which times
their heads push right into the substance. It seems possible
therefore that the "hairs" may function in the same way as a
cat's whiskers, acting as tactile sensors which warn the
butterfly if their eyes get too close to the dung, which would
almost certainly ( temporarily or permanently ) blind them if it
stuck to the surface of the eyes.
Bear in mind however that not everything in
nature has a "purpose" or "reason". It could simply be the case
that the hairs first appeared as a random mutation that was
neither beneficial or harmful, and consequently there would be
no natural selection pressure for it to "breed out" and revert
to a non-hairy eye.
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