Tuesday 18 February 2014

Australian Earwigs

Most gardeners in the temperate parts of Australia and in the northern hemisphere have a very negative image of earwigs. That is not unreasonable because the only one they see is the European Earwig, Forficula auricularia. This species feeds on flowers and vegetables at night rendering flowers useless and gardeners frustrated. European Earwigs are difficult to control because they really cannot be killed by spraying. They are "positively thigmotactic", like all earwigs. What this means is that they are "programmed" to spend most of their time in close quarters. So, during the day they can be found under rocks, in cracks in trees or, as with many Australian species, under bark. They, therefore, avoid the normal spraying control schemes.

Innovation is often the solution for earwig problems. A flock of bantam hens or Japanese Silkies can remove earwigs from a veggie patch-but they will also dine on the veggies. Some people crumple newspapers and the thigmotactic earwigs are drawn to the newspapers can be collected in the morning and the earwigs can be harvested.

But back to the Australian species. Even though we do have the European Earwig and one or two others that cause problems, we have some spectacular species. The world's largest and smallest earwigs can be found in Australia.

Earwigs are in the order Dermaptera. The Australian Faunal Directory has an important contribution to the knowledge of Australian earwigs. This has been compiled by Prof. G. Cassis and his colleague Dr Fabian Haas. A concise overview of earwig biology, ecology and the taxonomic knowledge of species is presented there.

Earwig biology can be complex. Females of some species look after the eggs and young. Males have pinchers that are larger than those of the females that are probably used in male combat. Although earwigs live in tight places, the chances of one entering a persons ear while sleeping at night, are very slight. But it can happen!

Briefly there are 85 described Australian species in seven families. It is estimated that three times that number probably exist on the continent. Australia is a hotspot for earwigs but generic endemism is low with only about 10% of the genera endemic to the continent.

 Echinosoma yorkense Dohrn; Pygidicranidae; Echinosomatinae
Aptly named, the genus literally means "spiny body". And when viewed up close, that's exactly what it looks like
  Echinosoma yorkense Dohrn; Pygidicranidae; Echinosomatinae
The spiny surface of the body of the Cape York Earwig.
 Apachys sp, probably queenslandicus; Apachyidae
A handsome large and very flat earwig that often flies to lights. Its rapid movments defy a good, close look but when tossed into the "dishwashing bin" the earwig is a bit befuddled for a few seconds and a good photograph is possible.
?Nala lividipes (Dufour) Labiduridae; Nalinae 
This earwig is a regular visitor to lights in the rainforest as well as at inland locales where eucalyptus and acacias are dominant.
 ?Nala lividipes (Dufour) Labiduridae; Nalinae 
Earwigs have an elaborate folding system for the large fan-like wings. Using their pinchers to aid in the folding process, the entire second pair of wings fit perfectly under the small first pair of wings (tegmina). The folding takes place in the "twinkling of an eye". 

 Cranopygia sp; Pygidicranidae; Pygidicraninae
This is large, spectacular species that infrequently comes to lights and when it does, it does not stay for long.
Elaunon bipartitus (Kirby); Forficulidae; Forficulinae
This earwig is often present in tremendous numbers and can be a pest. It can cover a light sheet and as dawn approaches, it can enter buildings and become a nuisance just due to its numbers. Like most earwigs it feeds on other insects. The pinchers can be used to hold the prey. 
Elaunon bipartitus (Kirby); Forficulidae; Forficulinae
This male has exaggerated pinchers that are probably used in male combat.

No comments: