Comments on: A different kind of snowy white with many insects

By: NatureShutterbug

NatureShutterbug — Sun, 21 Feb 2010 17:38:32 +0000

Very interesting. The holes in your photos are larger than anything I have ever seen on manzanita here. But now that you have pointed it out, here is a photo taken March 28, 2009, where the cutout can be seen still attached to the hole. I’ll keep looking at this issue when I go out again.

http://www.flickr.com/photos/deinandra/3483633625/sizes/o/

By: Lee Dittmann

Lee Dittmann — Sun, 21 Feb 2010 04:10:48 +0000

Somewhere in my brain cells, I did associate leafcutter bees with the flower holes, but when I tried to verify that during an inexhaustive search of the internet, all I could find was references to the alfalfa leaves Jim mentions, and rose leaves, if I recall correctly.

Lynn, on your images of the moths on the manzanita flowers, I’m not seeing their probosci entered within any hole at all, though maybe I’m missing something. I wonder if you did not just catch them in the act of probing the surface of the flower, perhaps looking for an entrance or perhaps finding some benefit from secretions off of the surface–or edible materials left behind by other visitors to the flower?

Dieter’s mention of bumblebees also cutting the holes leads me to wonder if they were not the likely maker of those I saw on Bryce Canyon A. patula. I’m supposing this because bumblebees are known to be able to fly earlier in the season than other kinds of bees–something about being able to detach the wing muscles and vibrate them internally to warm them up more than would otherwise be possible on cold days. The manzanitas there bloom in late April into May, while there is still snow on the ground at 7,000-8,000 feet elevations, and when even sunny days are still cool and nights still frosty.

Here are links to a couple of my A. patula images showing the holes:
http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&enlarge=0000+0000+1209+2115
http://calphotos.berkeley.edu/cgi/img_query?query_src=photos_index&enlarge=0000+0000+0110+2931

In the top image, it appears that holes have been cut on both sides of the same flower. The question is, with so many other flowers untouched, why this one? Is it that the presumptive bee could not reach the nectar on the opposite side of the flower, but that it is better to utilize a known productive source than cut a hole in another flower which might not yet be at peak production?

The lower image evokes a similar question, though it looks like the bee was carving a jack-o-lantern! You can see the cut flap of one of the holes hanging down.

By: NatureShutterbug

NatureShutterbug — Thu, 18 Feb 2010 03:36:56 +0000

Thanks for the info, Dieter — I have ordered the book. Marc Kummel also had some interesting observations of insects not accessing nectar in a normal way on manzanita:

http://www.fotolog.com/treebeard/58779987
http://www.fotolog.com/treebeard/58749582

By: Dieter Wilken

Dieter Wilken — Wed, 17 Feb 2010 23:04:40 +0000

Holes at the base of flowers are associated with what is called nectar-robbing. It actually is seriously studied by pollination biologists. A friend of mine wrote a review on the subject, in case anyone is interested: Inouye, D. W. 1983. The ecology of nectar robbing. Pages 153-173 in B. Bentley and T. Elias, editors. The biology of nectaries. Columbia University Press. Lee Dittmann’s comment is appropriate. The most common nectar robbers (> 90% of all flowers with basal holes) in temperate North America are carpenter bees and bumblebees. They cut the holes, because their probosci are usually too short to enter the flower in the usual way.

By: NatureShutterbug

NatureShutterbug — Wed, 17 Feb 2010 17:11:18 +0000

Thanks for the suggestion. I’ll look out for leaf cutter bees.

By: Jim Jakicic

Jim Jakicic — Wed, 17 Feb 2010 14:48:37 +0000

Leaf cutter bees cut holes in alfalfa leaves and other plants. Could this be the bee you speak of Lee?

By: NatureShutterbug

NatureShutterbug — Wed, 17 Feb 2010 06:27:07 +0000

Thanks for that clarification. There were all sorts of insects around that particular manzanita. It would be cool to see an insect in the process of making the tiny hole. It appears that the two lower moths in the collage were also not using the proper entrance, but had their probosci in, half way up the flower. I wonder how easy it is to make the holes, and if any of the insects have saliva that softens the flower cells.

By: Lee Dittmann

Lee Dittmann — Wed, 17 Feb 2010 05:32:28 +0000

Just to be clear, the round holes in the manzanita flowers are highly unlikely to have been created by any butterfly, which have sucking rather than cutting or chewing mouthparts, and tongues long enough to enter the flowers without such a shortcut. I think such holes were created by a bee of some sort, which do have the equipment to do the job, have short tongues, and would not be able to get their heads into the urns. Your caption, of course, doesn’t actually attribute the hole to the butterfly, just notes that it was using it. That’s an interesting bit of opportunism on the part of the butterfly!

I noticed the same kind of holes in the Greenleaf Manzanitas last year at Bryce Canyon National Park, though I never caught anyone in the act of either cutting them or using them.

By: Diane

Diane — Wed, 17 Feb 2010 02:26:48 +0000

Beautiful butterflies! All the flowers and nature make me so happy. I was out this weekend on Lost Valley Trail. Not too many flowers yet, but lots of water in the creeks and a general springtime feeling in the air.