Monday 31 August 2009

A Damselfly Ovipositing

In an earlier entry, I had a pair of damselflies of the species Prodasineura laidlawii in tandem, with the male hovering above and still clasping the female while she oviposits or lay her eggs in the fast flowing stream.

Well, not all damselflies do that.  It depends on the species and, sometimes, the circumstances. 

In one extreme, the male and female remain in tandem while the female oviposits and one such species is the Prodasineura laidlawii. On the other extreme, there are species where the male will not be around at all and the female would lay her eggs on her own.  The Ischnura senegalensis is like that.

Once copulation is completed, the male damselfly of the Ischnura senegalensis will let go of the female and fly away to perch elsewhere.  The female will then fly off on her own to find a suitable egg-laying spot and proceed to oviposit.

This picture here shows a female damselfly of the Ischnura senegalensis ovipositing in a grassy pond.

 

 

And here is another female of the same species ovipositing in a pond in the padi fields.

 

 

After ovipositing, the female will then find a perch to rest, bearing the muddy stains on her abdomen, which is often a tell-tale sign that she has been laying eggs...

 

 

Why is it referred to as ovipositing, you may ask? 

This brings us to the structure of the odonate body.  As mentioned in an earlier article, the males have accessory genitalia on the underside of the second segment (S2) of the abdomen.  The males also have superior and inferior anal appendages or claspers that emerge from the tip of the abdomen (S10), which is the last segment. 

Females odonates generally have shorter and stouter abdomens compared to their male counterparts and there is only a superior pair of appendages.  Females of some species have a sharp lance-like ovipositor on the underside towards the end of the abdomen, which is used to insert eggs into plant stems, rotting wood, wet soil or other plant materials.  While those of other species may have special flanges or non-functional ovipositors so there exists many different egg-laying strategies with different species of dragonflies and damselflies. 

Nevertheless, due to this structure in the female, when it dips its abdomen into the water or plants or roots to lay its eggs, it is referred to as oviposition.

 

 

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