Hoverfly "nasal" opening ?

[Lord V]

I trapped a hoverfly on the kitchen window yesterday (Epistrophe elegans) and then gave it some honey/sugar water to eat so i could take some closeup photos. It then cleaned itself and whist it was doing this I noticed a "nasal opening" appearing and disappeaing on the small bump hoverflies have on their face. It did not do this whilst it was actively feeding.

Never noticed this before- is it normal ?

Two photos with the opening appearing in the 2nd and a link here http://farm6.static.flickr.com/5069/...a4e7e5e3_o.gif to a multishot animation.

Brian v.

[nightshade]

That is really interesting Brian, it really shows in the animation. I will have to study my Stubbs and Falk!

[Lord V]

Originally Posted by nightshade

That is really interesting Brian, it really shows in the animation. I will have to study my Stubbs and Falk!

Thanks -wonder if something is not quite stuck together properly - suspect it is opening with proboscis movement.

Brian v.

[nightshade]

I can find no reference to the opening but will keep trying

[Bruce Williams]

Yes very interesting post Brian.

All very speculative on my part however...

My initial thought when I first saw your gif was that the opening and closing action was directly or indirectly related to the inflation and deflation of the proboscis pump. However you would've expected to see this happening while it was feeding - but you didn't.

So rather than the sucking action of the proboscis pump could it be related to the shortening and lengthening of the proboscis perhaps?

Bruce

[bigdave60dog]

It`s just that they have vertical mouths. If we could hear what he/she is saying what would it be?
Sorry, great video and a really good question but if you watch it with a silly hat on it is really funny as well.
Dave

[Lord V]

Thanks for the suggestions
Brian v.