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Miranda Hodgson

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Finding leaf-cutter bee eggs in compost

Posted by Miranda Hodgson on 27 Apr 2011 at 10:28 AM

We were up at the farm vegetable garden the other day, where I should have been busy weeding and sowing more seeds, but instead I had gone to see the nice lady who lives at the farm. We were rooting through her flower pots to see if the Canna rhizomes had survived the winter (they had), when I came across something exciting. Sifting through the compost, I unearthed what I thought were cigar butts for, at first glance, that is exactly what they appeared to be. A closer examination revealed them to the be something much more interesting: the carefully wrapped eggs of a leaf-cutter bee (Megachile centuncularis).

 

These are the bees that cut discs from leaves, often from rose leaves, and use them to form tubes, into which they lay an egg. The bee makes a tube-shaped burrow in soil, compost, gaps in rocks, old plant stems or dead wood and then lines it with pieces of leaf, so that one egg cell follows the next, like a string of sausages, with each cell being sealed with several layers of leaf discs. As the bee works, she will carry pollen to the nest and place some with the egg in each cell, until she has completed up to ten cells.

 

 

 

 

In early summer, the bees will hatch out, with the last to be laid being the first to emerge. It is said that the first bee out is often a male and he will wait for a female to emerge so they can mate and start the whole process off again. In the above picture, you can see an unwrapped egg next to the still-sealed leaf tubes.

I was concerned that by disturbing the burrow, the bees might not be able to find their way out once they hatched, but having asked around I was told that they would be able to burrow their way to the surface. As we replaced only a light layer of compost over them, hopefully this will be what happens and they will emerge some time in June.

Elsewhere in the garden, hornets (Vespa crabro) are looking for nesting places and three have been spotted flying around. I saw one crawl into this hole in one of the posts of a compost bay.

 

 

 

 

Although I watched and waited, it didn’t come out again, so it may have found a suitable cavity for laying eggs. Hornets aren’t the vicious creatures they are made out to be, but will defend their nests with vigour, so if it does use that post for a nest, we’ll just have to use another compost bay! Fortunately, that bay is pretty much full and we need to start on another one anyway, so perhaps it won’t matter.

Comments

Finding leaf-cutter bee eggs in compost | Gardening News said:

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on 27 Apr 2011 at 04:16 PM

sue1002 said:

I wonder if you will have another big wasp nest again this year.

on 27 Apr 2011 at 06:04 PM

Miranda Hodgson said:

I've been looking out for a new nest, Sue, and watching the wasps search for nesting sites. Hopefully, I'll come across one soon!

on 27 Apr 2011 at 07:24 PM

Miranda Hodgson said:

There are bees everywhere at the farm vegetable garden just now and in larger numbers than last year

on 29 Apr 2011 at 02:47 PM