Insect 'Flats'

Hymenopteran species in bamboo and drilled logs

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Back in 1993, I decided to try out a method of attracting solitary bees and wasps which was recommended by BWARS (Bees, Wasps, Ants Recording Society). They suggested cutting bamboo canes between the nodules, so that one end was closed and the other open, then hanging them in a really warm spot - ideally south-facing. Various species of solitary bees and wasps would then use these to make nest-cells and lay their eggs. The front of my study faces south and there is little interference from any full sun throughout much of the day. At one corner, there is a drainpipe, and it was possible to use the space between this and the wall as a place to hang bundles of these bamboos. The results were amazing, as well as rapid. Within a couple of months the ends of all 100 bamboos were closed up with various types of ‘cement’ used by bees to form their cells. The following summer a great many had insects emerging.

In 2000, further refinements were tried. Two old branches, one cherry and the other apple, were stood up against the wall and holes drilled in them, varying in diameter from 3 to 10mm; 8mm being favoured by the bigger leafcutter bees. It is important to drill these as deeply as possible so the insects have room for multiple cells. Search for the longest drills available, but do not drill right through the wood. Insects seem to avaid holes where they can look right through.More branches were added in 2002 and each year after; together with various logs, where the nest holes are drilled in the end grain. 

While mason bees, Osmia spp. seem happy with either bamboo or log, most of the other species, particularly the various solitary wasps, seem to go for the logs. Some of the older branches and logs already had minute beetle holes, many less than 2mm in diameter. The smaller digger wasps are frequently seen squeezing themselves into these and even manage to turn round and emerge head-first. So a practical range of holes could be said to be from 2mm up to 8mm, and these would be used by all likely nesters to be found in our gardens.

Some of the hymenopteran visitors are just that, ants and social wasps using the raw materials for their own nests, or looking for scraps of wasted pollen. But the majority are searching for suitable nest sites in a hot, sheltered part, under full sun. Before setting up these bamboos and logs, I rarely found any of these insects, now each year sees the number of different species increase. This is of particular importance, as it has become clear that, all over Britain, the number of pollinators have been steadily reducing over the years, with catastrophic potential for the future.

Nesting methods

Flats insects - Hymenoptera

Flats insects - other

Live identification


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