Tuesday, 14 October 2008

A Nesting Earwig

.....Order: Dermaptera

You might not think of female Earwig as being a nurturing mother but that is exactly what they are. Whereas most insects aside from the Hymenopterans will just lay their eggs and fly (or crawl) off, the earwig actually makes a nest. The other day, after moving a rock, I noticed a nesting earwig. With the roof of her burrow mostly gone she went about moving the eggs one by one into the far end of the burrow which was still a little bit more enclosed. We have a least six species on Tasmania. This one appears to be the introduced European Earwig, Forficula auricularia. In any case I replaced the rock and will keep an eye on them. Maybe I'll have a chance at photographing the hatchlings.

When the female European Earwig nests, it will form a little burrow under a rock or log where it will lay from 20 - 90 eggs. It will stay with the eggs to protect them and will even lick them clean to keep them moist and also to prevent fungal attack. After hatching, the first instar nymphs will stay with the mother. By the first moult (2nd instar) the young will start to forage but will still return to the nest. By the third instar they will be independent.

The cerci of an earwig are quite large and act like forceps. These can be used to tell male from female as the male cerci are much more curved. (See diagram)


(Click on Photos to Enlarge)

#1 - Forficula auricularia -European Earwig
Moving eggs after disturbance


#2 - Forficula auricularia -European Earwig
One to go


#3 - Forficula auricularia -European Earwig
All eggs present an accounted for
.


#4 -Sexual dimorphism in Dermapteran cerci (or forceps)


According to the "Catalogue of the Insects of Tasmania", the following species occur in Tassie:

Aanisolabidae
Aanisolabinae
  • Anisolabis sp
  • Gonolabis pacifica
Isolabellinae
  • Euborellia tasmanica
Forficulidae
Forficulinae
  • Forficula auricularia
Labiduradae
  • Labidura riparia
Spongiphoridae
Nesogastrinae
  • Nesogaster ruficeps





5 comments:

  1. Great sequence, Mosura! Even the backyard is home to fascinating fauna. I look forward to some pics of the earwiglets.

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  2. Thanks Snail - I hope to get a shot although from previous experience when you lift a rock with 'earwiglets' they tend to scatter really fast.

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  3. Could you pop a few into something like those old vertical ant farms and watch developments?

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  4. A great post Alan, I'll never think of earwigs in the same light again.
    Sorry, that should be 'Earwigs'.
    Gouldiae

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  5. Thanks Tony - I was thinking of putting some in a plastic container and seeing what happens.

    Thanks Gouldiae - I tend to capitalise nonspecific animal names like Kangaroo. I know you're not supposed to but if it is the "Common earwig" it seems odd to me to capitalise the word "Common" and not the name "earwig".

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