Waterveneers
arefoundabove
andbelowa
pond’ssurface.August 2020 BBC Wildlife 17WILD AUGUST
lying spread-eagled on the
surface film, having drowned
after mating.
As adults, they live only a
few days (hence ephemerella).
Even their mouthparts, like the
females’ wings, are vestigial.
Once mated, the females spend
the rest of their short lives
laying 300–1,000 eggs. Those
with wings disperse to find new
weedy water – an insurance
policy in case something drastic
happens to their pond. It also
enables different populations to
mix, which limits inbreeding.
Meanwhile, the wingless
majority row through the water
in search of weeds to lay their
eggs on.
The larvae look like pretty
regular green caterpillars, and
set about what all caterpillars
are good at: eating. It’s just that
they do it underwater. They
chew their way through an
assortment of pond plants
down to depths of over 2m,
then spend winter at the
bottom of the pond in a cell
made of silk and leaf
fragments. In spring, the
chewing resumes and, shortly
after, they mature and spin a
sub-aqua cocoon. Here, they
pupate, before starting the
wholewaterycycleagain.Iustrat
ons
by
Peter
Dav
dScott/The
Art
Agency
NICK BAKER
is a naturalist, author and TV presenter.Revealsafascinating
world of wildlife that
we o en overlook.Tohavea female that is, in
effect,nothing more than a bag
ofeggsis a relatively common
strategyutilised by many moth
species.However, the water
veneertakes it to another
level.Thewingless females
aretotallyaquatic. They spend
theirentire lives, from egg to
adult,submerged.
Inthesub-aqua world, wings
areasmuch use as canoe
paddlesmade of sugar paper.
So,theaquatic females have
exchanged wings for
long-haired fringes
on the ends of their
second and third
pairs of legs. These
oars, similar in form
and function to those
of water boatmen
(which are bugs), enable
them to row around with
ease. They breathe by trapping
a layer of air on their body,
which acts as a physical lung.
Gases from the water diffuse
into and out of it.Two worlds collide
The closest the aquatic females
come to the realm of air is
when they move to the surface
to mate with the males.
Sometimes the biggest clue to
the presence of a population
of these insects is the tragic
sight of translucent malesM
othsare
categorically,
unequivocally,not
dull.Needproof?
Ta k et h ew a t e rv e n e e r,Acentria
ephemerella. Whileit mayappear
ordinary,it is anythingbut.You
canfindthismothatanyweedy
pondinEnglandandWales(it’s
lesscommoninScotland).Visit
on a warm summer’s night and
you might be lucky enough to
see groups of males flying close
to the water surface, sometimes
in swarms.
Not much to look at, they’re
easily dismissed as just more
flimsy scraps of insect life, but
don’t judge a moth by its wings!
If you do, you’ll miss out on an
extraordinary life story.
Between June and August,
the male moths take flight on
their 6mm-wide wings. The
females, well, they don’t really
fly at all – at least, most don’t.
Therein lies one of the first
fascinatingly odd things about
the water veneer – there are two
forms of female. One is slightly
larger than the male and able to
fly (no surprises there). But the
more common type is wingless,
or brachypterous. Technically, it
does have tiny wing stubs, but
the effect is the same: it can’t fly.NICK
BAKER
N
Hidden
THE LIFE AQUATIC
Water veneers aren’t the only underwater moths.
Worldwide, a few hundred
species of moth are known
to spend their lives below
the water surface,
at least at the
caterpillar
stage. Several
occur in
Britain,
including
three china-
mark moths,but the water veneer is probably
the most sub-aqua species in
this country. In North America,
the water veneer has
been introduced as
a biological control
agent. Its mission
is to help stop the
spread of invasive
non-native plants
such as the
water milfoil.As camouflage, the
water veneer’s aquatic
caterpillars create a
hideout from plant
fragments.D I D Y O U
KNOW?WATER VENEER