Ivy mining bee

[PeterD]

I went back to the site that I saw these bees preparing their tunnels and found that they were using Ragwort and not ivy pollen.
Is this to be considered normal?





Thanks for viewing.

[Geoff F]

If there isn't any suitable ivy flowers present, such as early in their season, they appear to make do with whatever is available and accessible for them.

But they always prefer ivy flowers.

Last week I went to a site where I found them last year and they were doing well once again with many males searching around the burrows for females. I didn't encounter any feeding though.

[PeterD]

Originally Posted by Geoff F

If there isn't any suitable ivy flowers present, such as early in their season, they appear to make do with whatever is available and accessible for them.

But they always prefer ivy flowers.

Last week I went to a site where I found them last year and they were doing well once again with many males searching around the burrows for females. I didn't encounter any feeding though.

Thank you for your reply Geoff. It was that I did not remember seeing stands of ivy in the vicinity so I was curious about where they were getting their pollen from. Does this not suggest that they are not completely dependant on ivy and that they will feed their larvae on almost anything? If so, they are not as vulnerable as they could have been.

[Matt Smith]

Originally Posted by PeterD

I went back to the site that I saw these bees preparing their tunnels and found that they were using Ragwort and not ivy pollen.
Is this to be considered normal?





Thanks for viewing.

Depends exactly what they were doing with the ragwort. In one of your shots the bee is almost certainly a male going by the length of the antennae, and the second one also apears to be male. Male bees don't collect pollen, but they do need nectar to fuel their frantic flight activity over the nest sites. It is likely that these bees are just males refuelling at a convenient nearby nectar source.

Females also will sometimes visit other flowers for a nectar "top up", though once the Ivy comes into full flower they seem to get most of their nectar while collecting pollen.

[PeterD]

Originally Posted by Matt Smith

Depends exactly what they were doing with the ragwort. In one of your shots the bee is almost certainly a male going by the length of the antennae, and the second one also apears to be male. Male bees don't collect pollen, but they do need nectar to fuel their frantic flight activity over the nest sites. It is likely that these bees are just males refuelling at a convenient nearby nectar source.

Females also will sometimes visit other flowers for a nectar "top up", though once the Ivy comes into full flower they seem to get most of their nectar while collecting pollen.

Thank you Matt,

This is very interesting. I shall return to the nest site tomorrow and see if I can observe more.

[Geoff F]

Incidentally, Peter, how close to water is your site?

The 3 sites which I have located in my area are all extremely close to the sea or an estuary. Within around 200 yards.

I wonder if there is anything significant in this sort of location.

[PeterD]

Originally Posted by Geoff F

Incidentally, Peter, how close to water is your site?

The 3 sites which I have located in my area are all extremely close to the sea or an estuary. Within around 200 yards.

I wonder if there is anything significant in this sort of location.

Hi Geoff, This site is about 7 miles from the sea and is (for only a short time) farm land. There is a pond about 1/4 mile from the nest site but no running water. The land had been cleared and top surface cleared ready for building on about 4 years ago. The recession delayed all work and the fields were restored for farming use. This left an embankment at the side of the site entrance which is south facing. It is here that I found the bees.

Hope the description helps.

[Geoff F]

Yes that south facing embankment sounds typical for them. At one of my sites there is just a bank of about 1 ft alongside a track crossing a field but they seem to find that sufficient.

At the site which I visited recently there is a bank of around 8 ft and they only nest in the top 2 or 3 ft. A bit of a struggle to climb up as it is almost vertical; and my agility isn't what it used to be.

And trying to set up a camera tripod is another problem. So I use 2 short legs an one full length to give some sort of close but stable platform.

The European distribution map from the BWARS site shows some interesting 'hotspots' plus a lot of blank areas. But I don't know if there is anything significant in this bee's choice of locations. Possibly they just prefer low lying areas.

[PeterD]

Originally Posted by Geoff F

Yes that south facing embankment sounds typical for them. At one of my sites there is just a bank of about 1 ft alongside a track crossing a field but they seem to find that sufficient.

At the site which I visited recently there is a bank of around 8 ft and they only nest in the top 2 or 3 ft. A bit of a struggle to climb up as it is almost vertical; and my agility isn't what it used to be.

And trying to set up a camera tripod is another problem. So I use 2 short legs an one full length to give some sort of close but stable platform.

The European distribution map from the BWARS site shows some interesting 'hotspots' plus a lot of blank areas. But I don't know if there is anything significant in this bee's choice of locations. Possibly they just prefer low lying areas.

Thanks Geoff,

There are a few south facing embankments but the others are pretty well covered in vegetation. What makes this particular site different is that about 40% of the surface is sandy soil. Perhaps it is this that makes this site so attractive to them. Plenty of room for them to build tunnels relatively close to each other.

[eucera]

I am hoping to get the data added to the BWARS dataset again this year and so would obviously welcome full details on any records of C. hederae from anywhere (UK, CI or mainland Europe).

There was a paper (abstract in English) published in 2008 by Paul Westrich entitled: Flexibles Pollensammelverhalten der ansonsten streng oligolektischen Seidenbiene Colletes hederae Schmidt & Westrich (Hymenoptera: Apidae), in which Paul points out that C. hederae can collect pollen off other plants (usually Asteraceae) if the Ivy flowers are late into bloom.

Technically (using Mueller and Kuhlmann's terminology) the lectic status should be "Polylectic with a strong preference" (for Ivy).

You can download Westrich's paper from: http://www.wildbienen.info/downloads...-02_inhalt.pdf