Nature Notes
by
Philip Radford
I expect that most of us are impressed by the large size of the eyes of dragonflies
which, for the bigger species, seem to make up much of the head, with
such a different appearance from that of a butterfly. Butterflies have long, clubbed
antennae and relatively small eyes, while the antennae of dragonflies are
short and often inconspicuous. In contrast, the antennae of moths are big and
often broad and feathery, with those of the males being much larger than those of
the females; because of these sensitive antennae, some male moths are able
to detect the presence of females , by scent, over sometim es quite
remarkable distances. This long-range sensitivity is invaluable for night-flying
moths where the population is low, at least if they are to have a chance of mating.
With certain moth species, the males fly by day while females only fly by night;
an example here is the handsome Emperor Moth, with big eye spots on the
wings, and which is found on the Quantock moors and on Exmoor. The small
male Emperors, with big bushy antennae, fly on sunny days and are attracted,
by scent, to females as they rest amongst heather.
The thin, clubbed antennae of butterflies help the males to contact females by
scent as well, although sight plays a part with these day-flying insects. Additionally,
butterflies detect suitable flower scents using their antennae, so that the
insect can have a feed of nectar; a butterfly feeds by inserting its proboscis,
really a long sucking tube, into the chosen flower. Another use of antennae in
butterflies is that, by scent, the correct plant can be detected on which the
female can lay her eggs; often foot movements help release scent from a leaf.
If eggs are laid on the wrong plant, then hatched caterpillars are unable to feed.
Moths, like butterflies, feed on flower nectar but, for some species, this is only by
night. However, one day-flying moth is the Humming-bird Hawk-moth and, as a
migrant from Mediterranean lands, it can be seen, remarkably, flying in the sun in
Quantock gardens; it is instructive to watch the hovering insect as it repeatedly
inserts its long proboscis into suitable flowers. Last July I saw one of these moths
which had evidently found a rich feeding source on a single red valerian, and
was probing its proboscis into one multiple flower after another, and all on the
same plant. The valerian was clearly ripe with tempting nectar; no doubt it was
the sense of smell which guided the moth; there were other valerian plants around
but they were all ignored.
Vision must be very different for butterflies, moths or dragonflies than for ourselves,
although all the groups have colour vision of sorts. It seems that these
insects, broadly, can detect ultra-violet light and so recognise colour patterns on the case. Change is always with us, no two days are the same and even running
a heritage-tourist railway things change due to accidents, incidents or
changes to legislation. This in turn forces more requirements on the railway,
which have to be met or the railway would be deemed non—compliant and
would have to stop trading. I am thankful that we are able to comply and enjoy
the railway and countryside that it runs through, with the copper-capped
chimneyed engines plying the line to the sea.
Long may it continue, as I see lots of happy people enjoying the ambience of
it all and recalling happy memories of going to school or on holiday, by train.
My thanks to all of the people in the locality who support and volunteer for the
railway; it is thanks to people like you that the railway survives. May I wish all
readers a happy, healthy summer, enjoy your holidays, whether at home or
away, may it be a time of rest and relaxation.
Ian Aldridge.