January 2021 - earwig affection

January 2021 sightings has been converted into an earwig affection post.  I was very busy submitting my MSc thesis until mid-January and didn't have much time to go bug hunting.  Pretty much the only insect I saw was this juvenile earwig.

Juvenile earwig 31st Jan. 2021 (Forficula auricularia)

Earwigs are in the Dermaptera (skin wings) and in the UK we have four native species.

This little earwig (called a nymph not a larva) is a juvenile as there are no or very small wing cases visible - only adults have wings.  The name for earwig comes from the shape of their wings; they look like little ears.  These wings are a right faff for the insects to fold up again so they are not often seen in flight but here is a take-off video of an earwig.  Their wings fold out by spring-like folds to be 10 times bigger than the folded size and remain locked in place when not in use.  The wings are even used as models for some engineering projects.

They have filiform (thread-like) antennae, short leathery wing cases, a slender segmented abdomen, and characteristic pincers at the tip of their abdomen.  These pincers are used to help fold their wings up, for defence (they sometimes bend like a scorpion in a defensive posture), catching prey, and mating.

Earwigs eat a wide range of food so can be found in many habitat types, especially those with long grass, debris or anything to shelter under during the day.  Typically, earwigs are mostly active at night when they come out to forage; adults are especially common in autumn (April-October) and start becoming active in early spring again like these ones I found in my garden recently.  The pale earwig seen will have just emerged from a moult and will become darker with time.

Although they are non-social, female earwigs display amazing parental care for their offspring.  Here is an essay by Amy about earwig parental care:

The Long-Lost Tale of the Mother Earwig

The sun dips below the horizon and makes way for a full moon. The sky above is replaced with navy blues and twinkling stars, and a soft dew settles in glistening droplets across the stems of a grassy opening. The coolness of the air settles in for the night and everything is still and quiet. In a small burrow, at the bottom of the garden, something is stirring. A male earwig, stocky and dark brown runs from a small hole, quickly followed by a female. Their long legs moving furiously as she chases him away, raising her mandibles viciously at him. His work here is done. She needs to be alone. As soon as he is out of sight, she raises her large head, her black compound eyes glisten in the moonlight. She is readying herself for something. Her antenna brush along the grass as she moves through the undergrowth. A fallen apple provides a relieving meal and she munches at the bruised edges of a crevice, perhaps previously created by a hungry slug. A rustling nearby echoes through the stillness, sending vibrations under her. She stops. A small field mouse runs by, seemingly uninterested by her and now the coast is clear. She moves down from the fallen fruit, her elongated body moving to the curvatures of the soil, her cerci are straight, moving gently above the ground. She is close to the burrow now, it is time.

Beneath a large leaning apple tree is a long piece of slate that conceals the entrance to her chamber. It is small and modest, two inches under the ground. The earth around her is moist, providing well needed shelter and warmth. She is safe here. She spends the next few moments moving around, ensuring everything is cleared and ready. A ripple rolls through her swollen abdomen, her wing cases tight against her body. The time is here, Egg laying has begun. One after the other, she lays them in a specially made shallow egg cell. 1, 5, 10, 30, 35….she continues until forty tiny white eggs take up the space beneath her, but something is not quite right. She looks at her eggs and the urge to move them around one by one is strong. Gently holding them in her mandibles she shuffles them around until they are perfectly organised. That’s much better. Before the sun begins to rise, she curls up around her brood. She must rest.

The nights go by, and the mother earwig tirelessly turns and cleans her eggs. She removes any dirt and fungus and keeps them aerated. Come the seventh night, the eggs begin to move. She peers over her brood tracing them with her antenna, they are hatching now, one by one. Her tiny pale-white babies chew their way from within their casings, a handy first meal. The real job in hand starts now.

In order to give her brood the best chance at survival in a world full of predators, she must protect them, even from her own kind. She will not even risk them leaving before they are old enough to
find food. She will forage and regurgitate, much like parent birds do with their chicks. After many risings of the moon pass by, the mother earwig looks on as most of the brood thrives and with every moult they become more like her. Elegant and fierce. Their bodies shine a deep brown, brushing harshly against each other. Her chamber is too small for them now and they are becoming boisterous. It’s time to leave. The mother runs to the opening of a place she’s held strong for many months. Her brood stare at her, their eyes watching her as she moves away. Mother is gone now. Is it time for us to go now too? The first of her brood and one of the largest, rushes through the corridor to the entrance, closely followed by her siblings. they peer out. Cold fresh air washes over them and after short hesitation, they all disperse in different directions.

It is their turn now. Her daughters will go on to build similar chambers nearby, attracting males and to eventually mate and care for broods of their own. For her sons, they won’t be as lucky as to have a strong-hold. Instead they will spend most of their time congregating in bark crevices with other males.

The world of insects is a harsh place. One where even leaving shelter to find food can be treacherous, and everything eats everything else. But before you clear away earwigs from your gardens and greenhouses, remember the tale of the mother earwig who gave up her life to raise her young, and the male who spends his life running from her...

Amy Carter, Harper Adams University

References

Staerkle, M. and Kolliker, M. 2008. Maternal Food Reguritation to Nymphs in Earwigs (i). Ethology, 114, Pp.884-850.

Lamb, R.J. and Wellington, W.G. 1975. Life History and Population Characteristics of the European Earwig, Forficula Auricularia (Dermaptera: Forficulidae), at Vancouver, British Columbia. Canadian Entomologist, 8(104), pp.819-824.