28 August 2008

A butterfly that may have been laying eggs

As was mentioned in this post, one of butterflies I photographed last weekend was a Strymon melinus (gray hairstreak). I took several shots of that particular individual and later when I was looking at the pictures on my computer, I noticed that in most of the pictures the butterfly had the tip of its abdomen curved down towards the flower buds it was perched on.

StrymonMelinus3

I thought the butterfly was probably laying eggs and the brownish object sticking out from near the tip of its abdomen in the next picture was perhaps one of its eggs (it is more clearly visible in the original high resolution image).

StrymonMelinus4

I sent these 2 pictures to 2 lepidopterists I am in touch with, Torben Larsen and Don Harvey and both responded. One of them said:
...it is a female Strymon melinus exhibiting oviposition behavior. They usually lay eggs on flower bud of legumes or mallows, tucking them out of sight (between bracts, buds, etc.). The eggs are white, if I recall correctly. What you are seeing in the second photograph are the pair of ovipositor lobes at the tip of the abdomen (not eggs).
And the other one said:
I would think it is examining the plant in question while considering laying eggs. However, there does not yet seem to be a full commitment to so doing. I was going to suggest checking against the plant, but it seems that S. melinus will eat practically anything! The type of place is suitable for laying.
So now I know that a butterfly's downward curved abdomen is an indication of oviposition or at least, preparation for it.

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