Why do butterflies
rest in a head-downwards position ?
Hamadryas februa male, Yarinacocha, Ucayali, Peru ©
are several reasons for this. Many Nymphalids including
Prepona, Panacea and the Red
Admiral Vanessa atalanta habitually
bask high up on tree trunks, with wings outspread, and head
downwards. They often appear to be observing the activity below
them, and males certainly use these high vantage points to watch out
for females flying below them in the forest. An additional advantage
of adopting this position is that sunlight hits the wings more
squarely, allowing the butterflies to warm themselves more quickly.
Another reason is
linked to aerodynamics. Studies have demonstrated that butterflies
get greater 'lift'
if they take off from a head-downwards position. The hibernating
Comma pictured below has chosen a small branch just a few inches
above the ground as it's over-wintering site. The butterflies
probably make use of the heat reflected up from the leaf litter, and
in conjunction with the more efficient head-downwards take-off, can
become airborne more easily on the cold but sunny days of late
winter and early spring.
Polygonia c-album, hibernating openly under a low branch ©
Tropical Riodinids such as
Eurybia habitually rest beneath low
growing foliage, and probably make use of the same factors to enable
them to take flight very rapidly, to intercept potential mates.
species, probably molochina, Madre de
Dios, Peru ©
Where do butterflies
go when it rains ?
Most species shelter under leaves when it
rains. They can often
detect the approach of wet or windy weather
several hours before it's arrival ( by sensing changes in humidity
and air pressure ), and take shelter well
in advance of rainfall.
observed this many times especially in the neotropics
Sisters and many other species
suddenly disappear under leaves even when the sun is shining. You
can be sure however that when they do so
things are on the change. Clouds quickly roll in, and an hour later
it's pelting down.
There is a short account of my
observation of similar behaviour by
Gonepteryx rhamni in England, on
Gonepteryx rhamni roosts under leaves at night or in wet
butterflies shelter under leaves though.
Some such as Peacocks
hide in rabbit burrows, while Commas go into log piles or hollow tree
Orange tips just sit it out on the
surface of a leaf or on a flower head. Blues, browns and
most skippers rest openly
on grasses in dry weather, but the threat of rain sends them
deep into grass tussocks for shelter.
stay out in the open even during prolonged spells of bad weather -
in May 2006, I studied one particular female Dingy Skipper which
spent no less than 13 days sitting on the top of a knapweed plant,
with it's wings wrapped tightly around a
dead flower head.
It endured heavy rain, hail, sleet and strong winds during this
period, with no opportunity to feed. The butterfly is superbly
camouflaged when resting on knapweed seed-heads, where it is
overlooked by insectivorous birds. By roosting high on the
seed-head, it is also able to escape predation by rodents, which
might more easily locate an insect that chose to hide amongst
grasses at ground level.
Dingy Skipper, female at roost, Selborne, Hampshire. During
prolonged periods of wet weather, the butterflies remain out in the
open for a week or more, with their wings wrapped tightly around the
dead flower heads of knapweed plants ©
Why do butterflies
When butterflies first appeared on Earth, the present day continents
were all connected to form one giant land mass. Nature tries to fill
every available niche, so butterflies would have naturally been
nomadic, their colonies moving seasonally from one area to another
in search of suitable habitats.
As the continents drifted apart, species with weak flight became
increasingly unable to cross newly forming natural barriers such as
oceans and mountain ranges. Certain species however were more
robust, and managed to overcome the barriers. In some species the
inclination to migrate became imprinted genetically, and they still
migrate today - if/when environmental conditions are suitable.
The most famous migratory butterfly is the Monarch
Danaus plexippus, which migrates
annually over a distance of 2000 miles ( 3200km ) between it's
northern breeding territories in Canada, and it's southern
over-wintering grounds in Mexico. Read more about the Monarch
The story of the Monarch -
Why do Hairstreaks rub
their wings together ?
Hairstreaks usually have a pattern of lines or stripes on the
underside wings. These, in combination with ocelli ( false eye
markings ) and short tails ( false antennae ) act to divert
attention away from the head, and towards the outer edge of the
hindwings. By oscillating the wings, the tails are made to wiggle
like antennae, further increasing the illusion that the butterfly is
Attacking birds will always aim at the head of a butterfly, but are
tricked into aiming at the tail. The butterfly is thus able to
escape in the opposite direction unharmed. Another reason for
wing-rubbing is that male Hairstreaks have patches of specialised
wing scales - 'androconia',
located on their upperside forewings. Sacs at the base of these
scales contain pheromones. Rubbing the wings together helps to
disseminate the pheromones, which attract females and induce them to
Spindasis seliga, Gopeng, West Malaysia ©
Why do Whites bask
with their wings half-open ?
This activity is called
reflectance basking. Butterflies with dark wings usually open them
fully when basking, to expose the maximum area to the sun's rays,
enabling them to warm up rapidly and gain energy.
Whites, Blues and
Coppers however have wing surfaces which reflect, rather than absorb
solar energy. Consequently they bask with their wings half open, so
that the heat produced by sunlight falling on the dark thorax is
contained within the
of the half-open wings, rather than being dispersed on the breeze.
Pieris rapae, 2nd brood female,
Noar Hill, Hampshire ©
How much rainforest is
destroyed every year ?
A very difficult question to answer, because some areas are entirely
destroyed, while other areas are left semi-intact, but severely
excess of 10,000 square miles ( 2.6 million hectares ) of the Amazon
rainforest is deliberately burnt down every year, primarily to make
way for cattle pastures. These pastures are very poor in nutrients,
so support only very small numbers of cattle. The pastures are
burned annually to promote new grass growth and to destroy cattle
parasites. These fires rage uncontrolled, setting fire to further
areas of forest. Deforested areas are much hotter and drier than the
rainforests - consequently the average temperature of the entire
region rises and the humidity falls even more dramatically. This
causes major changes in the vegetation structure of the remaining
areas of rainforest, leading to reduced biodiversity even in
Rainforestspages to see how YOU can
help to protect the areas that remain.
What are the red
bits on this
Marbled White ?
White Melanargia galathea, with
breei mites on thorax ©
Adult butterflies, particularly the
males of Meadow Brown Maniola jurtina,
Melanargia galathea, and Common Blue
Polyommatus icarus are commonly parasitised by these red
mites Trombidium breei, which normally
attach themselves to the thorax of the butterfly.
They transfer from host to host
when the butterflies alight to nectar at flowers. Studies on Meadow
Browns have shown that the mites have no detectable effect on the
flight performance, orientation ability or lifespan.
do Danaines feed at dry, dead plant stems ?
The habit which butterflies have of feeding at dry, dead plant
stalks is not confined to Danaines – it is also very common amongst
Ithomiines, and not unknown amongst Satyrines and Nymphalines. I’ve
even seen White Admirals doing it in Britain.
Only male butterflies indulge in this habit. The purpose is to
acquire pyrrolizidine alkaloids, which in the case of Danaines and
Ithomiines are chemically converted into pheromones.
These are later disseminated via
scales on the abdomen ( Danaines ) or
wings ( Ithomiines ), to entice females
are also known to be toxic to birds, inducing vomiting, so that a
bird which has tasted an Ithomiine or Danaine is unlikely to attack
another similarly patterned butterfly. It is also likely that the
alkaloids are passed to females during copulation, and may be vital
in the production of viable eggs.
How are butterfly populations monitored ?
is one of several methods used to monitor butterfly populations.
Other methods include
This method involves an individual or group of
individuals who undertake a regular weekly walk that follows
a fixed route through a butterfly habitat. The route is divided into
sections, each representing a different sub-habitat.
A transect at a woodland site for example might
include a section through a recently coppiced area, another section
through a fir plantation, and another through a stand of mature
The butterflies seen in each section are counted, and the figures
compared to those obtained in other sections, or from the same
section in past years. The figures
do not represent accurate population counts, but
are of value in assessing how numbers fluctuate in response to
management factors such as grazing or coppicing regimes.
method has many disadvantages - a) conspicuous species such as Small
Whites or Brimstones can be easily counted, but smaller and duller
species such as Dingy Skippers and female Chalkhill Blues tend to be
greatly under-estimated; b) butterflies flying in open grassland are
more easily counted than those in woodlands; and c) the numbers of
each species which are active and observable vary greatly according
to climate, local weather conditions, time of day and other factors.
This method involves
capturing every individual of a particular species, numbering and
tagging it by marking it with a spot of paint, and releasing it. The
following day the process is repeated, and the number of
butterflies is counted, while
are themselves marked. Over a
2 or 3 week period
it is possible to analyse the build up of populations, the lifespan
of individuals, and the movement of individuals from one part of the
site to another.
The disadvantages are
- a) it is not possible to know why individuals go
- do they die, do they disperse or migrate, are they simply
copulating or resting and thus not captured ? b) this method works
quite well for certain species at small sites, but is impracticable
at large sites, and impossible for species such as Purple Hairstreak
which spend all day at the top of oak trees.
This method uses a
and calculation. An experienced entomologist might e.g. walk around
a grassland site counting the numbers of male Chalkhill Blues.
Perhaps he / she counts a total of 300 males in an hour.
This is doubled to
600 to take account of the female percentage of the population. Next
it is multiplied by a factor which takes into account the area of
the site where similar habitat occurs - perhaps the walk only took
the entomologist through 10 percent of the habitat, so the figure
would be multiplied by 10 to give a total of 6000.
The count only took
place for one hour, on one day, but the species may have a flight
season lasting several weeks, so other factors must be taken into
account : What percentage of the total population had yet emerged ?
What percentage were flying during the hour that the count took
place ? Various formulae ( arrived at from mark and recapture data )
can be applied to calculate the approximate total population size.
counted number of individuals ( 300 ) by the appropriate factor
might result in a total population size as small as 1000, or as
large as 20,000, depending on the size of the site, the available
habitat, the behaviour of the butterfly, and at what stage in the
flight season the count occurred.
The disadvantages of
this method are - a) it is highly subjective - for it to have any
comparative value, the same entomologist and the same formulae would
have to be used at every site; b) areas of a site that appear to be
identical may hold vastly different numbers of butterflies - e.g.
some areas might have a deeper soil - a factor that affects the
vegetation mixture, sward height and microclimate.
What to do with a hibernating
butterfly in my house ?
The best course of
action is to put the butterfly outside, making sure it is cool and
protected from wind and rain, but in a position where the sun will
reach it when it is time to awaken in spring.
You could place it
within a pile of logs for example, in a hollow tree trunk. The most
important thing is that it must have an escape route, and must be
protected from birds, and from spiders ( so don't put it in a shed
or greenhouse ).
If the butterfly
wakes up and flies away on a sunny day in the winter it will find
its own way to another safe hiding place.
What is the biggest insect that
ever lived ?
Fossils of a prehistoric dragonfly
Meganeura monyi from the order
Protodonata make it the largest insect ever to be found, with a full
wingspan of 30 inches and a body length of 18 inches. The
Meganeura dragonfly lived about 250
million years ago until it became extinct at the end of the
Paleozoic Era. It flew in Britain and France at a time when the
climate in Europe was tropical.
What is the fastest flying butterfly ?
Danaus plexippus is thought to be the
fastest flying butterfly, with a top speed of up to 20 mph in still
air. However several hawkmoths ( Sphingidae ) have been measured at
speeds of over 30mph. The fastest flying moth however is the
Black Cutworm ( Noctuidae ) Agrotis
ipsilon which can reach flight speeds of up to 70mph /