CLOSED: Eristalis tenax ?

Taken in spring this year. I had a lot of these feasting on my crocuses!

Another one that had lighter patterns on its back.

Still another one taken this year;

Just found another one of this spring that gives a more frontal view

I think you are right on all counts, but these can be tricky! Wide apart eyes, female, close together, male. Females of E. tenax can vary greatly with the abdomen pattern, the hind legs are dark which looks to fit.

I have a key somewhere if I can find it, I have identified 3 species I have positively, another 2 tentatively, I may have more!

Look here, there are many more. The link is not holding the page, go to the Image Gallery at top left, then find Syrphidae.

http://diptera.info/

This site has a lot of information, and this is where I found the Eristalis Key which now doesn't appear to be working! I put a link for it on one of my Eristalis entries in BF which also doesn't work.

http://www.microscopy-uk.org.uk/mag/artmay07/cd-hoverflies.html

I copied the main part of the web address, if the link doesn't work do the same and it will bring the site up, but it's slow to load. There are many different links to ID keys.


http://home.hccnet.nl/mp.van.veen/index_e.html

Just adding that I can't see an Eristalis key, I wonder if it is being worked on and that's why it's not available.

This message was edited Aug 15, 2007 3:12 PM

Thanks Wallaby! These are indeed very interesting sites! The links worked perfectly for me. It will be very useful for future ones to ID!
There is one thing which is not very clear yet for me; (I am just a beginner and not used yet to the complicated system of differentiation and naming of the insect world) The images listed under the genus Eristalis (in the second link when one clicks on the key Eristalis species under comments) are then subspecies ? But why do these subspecies have two names instead of one ? One could get confused and think the first is the genus and the second the specie.
For example there is one called Leucozona lucorum.
Is its full name then Eristalis Leucozona lucorum ?

I also didn't find a key for the Eristalis genus in the Dutch site.

I think that I can mark this thread as solved I will asume that mine are all Eristalis tenax. It is too hard to tell by my pictures whether they are males or females. That eye-area is so dark that one cannot really see if the eyes are close or far apart.

The link just takes you to the picture (or near) of an Eristalis, they are in the family Syrphidae. There are many different Genus and speices in the family.

The Eristalis key which I mentioned is in the section under all of the pictures, #10, it no longer exists but the keys can give you the clues you need, sometimes though you have to have a specimen to determine at which angle the hairs on a leg go!

This was useful when I ID'ed some, such as E. arbustorum has a near white face, E. pertinax has a broader dark stripe down the centre of the face than E. tenax, it also has a triangular shaped tail and yellow on the tibia on the hind legs. Such a shame it isn't available!

Yours are all female, in Eristalis the male's eyes are noticably together and large, although near the back where they join there is always a small 'knob' the eyes meet well in the middle.

Here is an example, female on the left, male on the right. I haven't positively ID'ed this one, but think it could be E. similis purely by comparison, I have no key!

Yes I understand that; quote: 'they are in the family Syrphidae. There are many different Genus and speices in the family.'
that's the same as in plant terminology.

But I meant that when you click on '(a) Erystalis' the first one under 'comments' under fig.3 of http://www.microscopy-uk.org.uk/mag/artmay07/cd-hoverflies.html it gives all these what I imagine to be subspecies.

Thanks, your last picture made the difference very clear! What a good shot!
It looks like I had no males around at the time!

If you scroll down the page instead of clicking on the link as you stated, it will take you to the same pics. It's only a shortcut and not another page. I hope that's clearer!

I found I had pics of E. tenax female last year and earlier this year, yesterday I was sorting all the Eristalis pics (rainy day like today) giving them numbers with the Genus name so they would be together, I had over 80 plus already named pics!

That looked daunting, but I put some names to many of them, the three I already knew plus some I had a good idea of their ID. I found myself wondering what a certain male was, it took a while to realise it was most likely E. tenax, it must be more shy as some others seem to be present in pairs.

However, I can't be certain that it is, as the dark patch on the face looks broad which would suggest E. pertinax, but it doesn't have yellow tibia on the back legs! The pattern on the abdomen fits. See how difficult it can be!

Here is the handsome man cleaning his tongue,

This message was edited Aug 15, 2007 8:58 PM