Teaching children about nature-5-Earwigs

There is probably no insect more widely known than the common earwig, Forficula auricularia,. It is to be found in all seasons of the year, and in suitable weather, and in certain locations, they can become so abundant as to be a nuisance in gardens and even in houses.

Earwigs belong to the Order Dermaptera and is found in both north and south Africa, Eurasia, Australia and New Zealand. two thousand species occur in twelve families and are one of the smallest insect orders. 

It is an omnivorous { feeding on a variety of food of both plant and vegetable origin} feeder, eating petals of flowers, ripe fruit and other sweet substances. In days gone by these creatures were often encountered on the 'sugar' mixture placed on tree trunks by moth collectors.

The name earwig is said to derive from the fact that these insects will crawl into the ears of persons asleep. this was very much believed. Many countries have names which referred to this belief, such as the French Perce orielle, the German ohr-wurm, and the Swedish Or-matk { matk meaning a worm} indeed our name of earwig means ear worm from the Anglo Saxon wigga {worm or creeping thing}. others suggest it derives from the old English eare {ear} + wicga meaning insect.

It is undeniable that earwigs are very fond of hiding in dark holes and crevices, however, crawling into the ear id not impossible but improbable, in these modern times. It could very well have been more probable in the days when man slept in caves or among straw employed as bedding or for stuffing pillows.. The name could also refer to the fact that the shape of the wings of this insect are superficially like the shape of the human ear.

Earwig-Image courtesy of " Fir0002/Flagstaffotos"  {Non commercial unported 3.0 license}

Characteristics of the earwig

The head has compound eyes. The antennae are thread-like and normally consists of 14 joints, but a smaller number perhaps because of injury are not uncommon. The jaws are typical of biting insects, having a pair of strong mandibles., a pair of first and a pair of second maxillae, the latter united to form the lower lip. In general these jaws are not very different from those of the common wasp. The prothorax is large and freely moveable, and the mesothorax  {middle}.

In the adult the mesothorax carries a pair of elaborately folded and very delicate fore wings, whose extremities when folded project a little distance behind the wing covers.   The legs are set wide apart and typical of the insects although the tarsi only have three joints. The wings are remarkable and characteristic. The front pair are merely covers for the hind wings. They are small and hard and of the same colour as the rest of the body.

The hind pair when expanded are of considerable size and very thin, but when at rest are folded in a more complicated and beautiful fashion, then tucked away beneath the fore wings with the exception of the small projecting portion. This projecting piece alone is darkly coloured and relatively hard.

This concealment of the hind wings is so efficient that many people are not even aware of their existence. the common earwig is rarely seen on the wing for it undertakes this function of movement during the hours of darkness. They hide away during the daylight hours. They hide away during the hours of daylight. However, there is a smaller species that may be more often encountered on the wing at dusk as it flies at dusk seeking out flowers. Labia minor is habitually earlier on the wing than the common earwig. 

Lesser earwig.Labia minor--flies at dusk much earlier than the common species.

Image courtesy of Whitney Cranshaw,Colorado University Bugwood.org { Creative Commons attribution -3.0 United States License}

Wings of the earwig.

The wings are attached in an unusual manner, for the hard part of each is continued towards the mid dorsal line until in meets the other. The folding of the wings is much more complex than is the case in any other insect species. In the ' Book of Nature Study'  { 1909} JB Farmer explains it as follows--" The lower radiating veins come together, creasing the the delicate membrane between them fan-wise. A cross fold then is made rather near the basal hard part, and is followed by a second cross-fold in reverse direction, close to the line of dilated spots, on the divergent veins, a contraction occurs close to the base, so that the whole folded structure is compressed, the softer parts passing below the hard, the abdomen is turned up and the nippers at its end employed to push all safely 'home' "

The abdomen comprises of the usual ten segments and terminates in  a pair of horny pincers. the forceps {pincers} are almost straight with rough inner edges. The middle of them are curved into a semi-circle, strongly toothed at their contiguous {sharing a common border} bases, but smooth on their curved parts. The size and shape tend to vary greatly as is often the case with specialised organs of this type.

The main defence  of this insect is one of concealment, hiding away in tiny nooks and crevices, here it is safe from all but the most tenacious predators. However, it does produce a disagreeable odour, which can be noticed more easily if specimens are kept in a a small tin, or any article in which these animals congregate for shelter and safety. This odour is produced by special glands situated on each side of the dorsal surface of the second and third segments. the position of these glands can be seen with the naked eye { more so with the aid of a magnifying glass }. The location is evident by a slightly raised line which ends in a slight fold at the hind edge of the dorsal surface of the segments.

During the winter, the insects bury themselves in the soil or in heaps of decaying vegetation.  the eggs of earwigs are laid in spring, and hatch out within a few weeks. The female watches over her eggs and gathers them together again should they be disturbed. Unlike in the case of many insects there is no metamorphis. the young are wingless and in form resemble the adults, although the forceps are of a different shape and the joints on the antennae are less in number. However, they grow at an impressive rate. they moult their skin three or four times, and by August of the same year have attained maturity. The female is said to show some affection towards her young

Male common earwig.

Earwigs and man

Earwigs are especially disliked by gardeners, whose carnations, dahlias and chrysanthemums they are apt to nibble. In days gone by I remember gardeners using hollow stems of cow parsley and elder to trap earwigs. One end of the tube was blocked, the tube is then hung with the open end downwards. In these more modern times a simple two inch plastic pot/cup filled with straw and placed upside down on the top of a garden cane will suffice. It is the nature of earwigs to crawl for shelter in any recess  and the such convenient places as provided will tempt them in.

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