Hoverfly ID Confirmation.

[TeresaW]

Are these two syrphus ribesii ?

Are there lots of variations in the markings, they don't look quite the same as the ones in the Gallery.

[squishy]

Not S. ribesii certainly.

Maybe Chrysotoxum sp..

[TeresaW]

That was quick!

Thanks Squishy, they didn't look quite right, which is why I asked.

[oxycera]

Dsysyrphus albostriatus

[TeresaW]

Thank you, spot on! I couldn't find it until now.

[TeresaW]

One more question.

How do you tell the difference between male and female? I've stared and stared at various photos but can't see it...


I didn't realise there were so many different hoverflies, and they have really captured my imagination, not least because they are sometimes a challenge to actually photograph on my little point n shoot digital camera... Good macro shots if it stays still long enough, if not, a leaf, or a blurry backside is all I get

[Jason Green]

Evening Teresa,

Look carefully at the eyes - if they really meet-up then it's a male, and if the eyes appear smaller with a gap between them it's a girl, in a nutshell...

Look at the following two images (taken from my collection);

Female on the left, male on the right
Species: Syrphus ribesii

...look at the way the female's eyes never touch in the top center, though the black area between them can make them appear joined under poor light in the field (the black area contains the three ocelli in a triangular arrangement, which are 'simple eyes' likely used to detect light changes indicative of predator-approach, or to stabilise flying by light and shade). The male's on the other hand touch and even appear joined almost down as far as the base of the antennae.

There are 276+ species in the UK, though not all can be done from photographs. Some need specimens retaining for close scrutiny of legs or very subtle wing structures. Some even need the male genitalia examining!

For future reference, a photo of the top-down (be sure to try for the abdominal patterns, they can be easily obscured by sun-reflecting, shiny wings!), side-on (for leg colour, important for some!) and a head photo (good to seperate some Dasysyrphus sp. by colour, among others and of course antennae). Still, as I said not all can be photo-ID'd.

I hope this helps.

Take care,

Jason

[TeresaW]

Thanks Jason, that's really helpful and fascinating.


Is the eye thing general in all hoverflies or particular to Dasysyrphus albostriatus?

[Jason Green]

Sorry, I think I was still editing after you replied!

This method can be used for all Hoverflies I imagine, and indeed some Blue-bottles and Tachinidae members for example, but not all flies. With mosquitoes for instance, you need to look at the antennae (fluffy - male, short and hairless - female).

The more practice you get in the field or even web images you get, the more definite you'll feel when deciding. Trapping in a clear pot may be good practice.

[TeresaW]

Thank you Jason, and good tips for photos too.

It'll take a lot of patience to get those three shots...as most of them are about shoulder height in the middle of a huge bramble!! I'm going to have some fun this weekend with them all.