insect homes

[colin keegan]

I have a few cross cut sections of tree stumps approx 30-40 centimetres across and approx 15-20 centimetres thick, if i drill holes in these are they likely to be used by carpenter and bumble bees etc, if so what size holes and where would be the best place to site them, i have a fairly large garden with quite a few various type trees friut, evergreen, etc

[eucera]

It is great to hear of your plans and intentions - not everyone is as enlightened as you are.

With regard to species and hole sizes. Firstly we have no resident species of Carpenter bee in UK, and the only one that ever visits here (Xylocopa violacea) will dig its own burrows in softish, rotten wood. No bumbles nest in tree holes such as you would drill.

However, its not all bad news. A number of solitary species such as Red Mason-bee and the Blue Mason-bee, along with several leafcutter bees and their parasites, will readily take to holes. 6mm is perfect for the smaller species and maybe as large as 10mm for the biggest. I would drill a selection, but with the majority of holes at the 6-7mm size.

Let us know what you find when the bees are out and about next year

[John_M]

I have 2 insect houses, one is a hawthorn log, the other made of scrap spruce; most of the holes I drilled were 8mm, a couple of 10mm, and a selection of 4mm and 6mm holes. Most of the 8mm and 6mm holes are now sealed with either mud or bits of leaves, and I've seen bees in them, and the smaller holes are mainly blocked with mud. Some of the smaller holes are home to spiders. Should be interesting to see what emerges in the fullness of time.
Interestingly, I have one shop bought nest which consists of 8mm cardboard tubes inside a larger plastic tube, which appears to have been largely ignored.
The most popular one faces East in a sheltered spot agaist a wall, the other two face South.