[Syrphidae] Re: Sex identification based on abdomen coloration

[Wouter van Steenis]

Dear Malin and others,

For Eristalis arbustorum I’m quite convinced that it is by far more easy to distinguish males and females in the field than to distinguish between females of Eristalis arbustorum, E. abusiva (in Europe) and E. brousii (in North-America) and between males of these species. It is not only the color distribution, but also the brightness of the orange spots. And males tend to have more hairy bodies. However, there is a rather small proportion of really dark males and really light females that do overlap in coloration. 
So in my opinion anyone who claims to have recognised one of these species in the field should for sure be able to say what sex it was. 

In E. tenax it is quite difficult due to huge variation in coloration. The males being much more orange, the females being much more black, but with a very extensive overlap. The form of the abdomen might be a bit more helpful, but I only sex them based on the separation of the eyes. 

In E. intricarius (hair coloration) and E. pertinax (form of abdomen) it is quite easy to separate almost all specimens.

best wishes,

Wouter



From: Francis Gilbert 
Sent: Wednesday, February 10, 2016 9:24 AM
To: Hoverfly discussion list ; malin.thyselius at gmail.com 
Subject: [Syrphidae] Re: Sex identification based on abdomen coloration

hi Malin

 

Do you know the attached papers? Graham Holloway did a lot of work on the variation in colour pattern in arbustorum, and Jon Heal also on tenax, arbustorum and intricarius

 

Best wishes

 

Francis

 

 

Dr Francis Gilbert

Professor of Ecology

Room B132, Biology Building, School of Life Sciences

University Park, University of Nottingham, Nottingham NG7 2RD, UK

Tel: +44 (0) 115 951 3215

website: www.nottingham.ac.uk/~plzfg

                ecology.nottingham.ac.uk

 

From: syrphidae-bounces at lists.nottingham.ac.uk [mailto:syrphidae-bounces at lists.nottingham.ac.uk] On Behalf Of Malin
Sent: 10 February 2016 08:16
To: syrphidae at lists.nottingham.ac.uk
Subject: [Syrphidae] Sex identification based on abdomen coloration

 

Hi,

 

During this years field season I have started to consider whether the coloration of the abdomen can help in sex identification, particularity of Eristalis tenax and Eristalis arbustorum. My feeling is that the most brightly coloured individuals appear to be male, whereas the individuals with darker colours could be either male or female. Have anyone noted something similar or do you have another way to quickly determine sex in the field (except for the difference in eye morphology, which even though useful can be a bit tricky in some field situations)?

 

Best Regards

Malin Thyselius

 

 

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