Bee boxes, houses, condos and hotels…Part 2: The photos

by Christine Hanrahan

It is said that a picture is worth a thousand words and, bearing that in mind, I am posting some photos of a couple of bee nesting structures.

The large nest box made by Agriculture and Agri-Food Canada scientists has holes of varying sizes and contains rolled up tubes of paper that can be removed. At the end of summer, these paper tubes would be placed in a container in a refrigerator or unheated building for the winter and brought out in spring in a place where the bees can emerge safely. The nest box itself would be disinfected before being re-used.

The old bee box from 2009 was made for us by Bruce Burns and used as part of a display on pollinators. Later, in mid-summer, we placed it in a south-facing site, protected from intrusion and, within days, leafcutter bees (Megachile) were using it.

Bee bundles are another method of providing homes for tunnel-nesting bees and, in this photo, you can see how the bamboo bundles were placed inside a plastic plant pot for protection from the elements.

The next two photos are of two different bees using the bee boxes. The Megachile is checking out the old box in 2009, while the mason bee is investigating the newer box in 2012.

There is a close up of the rolled paper tubes in this next photo.

The last photo shows a tree swallow nest at the FWG, removed when the box was cleaned in early November. Inside were many dead bumble bees and, beneath the straw of the swallow nest, were many “honey pots” made by the bees.

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Bee boxes, houses, condos and hotels…

by Christine Hanrahan

This is a simple overview of various types of accommodations for bees. I won’t be providing instructions for building bee boxes, but I do provide a reference below for the best all-round source for creating different types of bee houses.

Much media attention has been given to declining honeybees (Apis mellifera), but less well-known is the decline in many native bee species, such as bumble bees (Bombus) and others. Our native bees are facing habitat loss, pesticide contamination, disease, and who knows how many other problems. Studies are ongoing with more research devoted to this issue.

The good news is that people are becoming more aware of bees as beneficial. I spoke with a pest control official recently who said that although he still gets calls from people worried about bees, such calls are fewer than in the past. The ongoing media attention about disappearing honeybees and subsequent attention paid to bees in general, and their importance to pollination, has moved this group of insects into a more benign category.

One indication of the changing attitude is the recent interest in placing bee boxes (bee nest sites) in gardens. Although I am happy about this trend, there is also a downside. Buyers are not usually told that if they want to help bees, nectar rich plants must be available or bees won’t be interested. The importance of hygiene in bee boxes is rarely discussed either. Unfortunately, some commercially produced bee boxes are more concerned with making cute ornamental art for the garden than with the requirements of bees.

Many of our native bees are ground nesters and won’t use bee boxes. This brings up a whole different issue, which I’ll leave for another time, as this article is looking only at tunnel-nesting bees, the ones most likely to use bee boxes.

The natural nesting sites of these bees is the hollow stems of plants, such as wild raspberries, or holes in standing dead trees (snags). When we build bee boxes for them, we are emulating their natural nest sites, much as we do for cavity nesting birds when we install nest boxes.

The most common tunnel-nesting bees we see around the Ottawa are leaf-cutter bees and mason bees (both in the Megachilidae family). These are the ones that will be most attracted to bee boxes. Bumble bees may also be attracted to man-made nest sites. At the Fletcher Wildlife Garden (FWG), a newly installed bee box in summer 2009, attracted leafcutter bees (Megachile) within days. In 2012, scientists from Agriculture and Agri-Food Canada (AAFC) placed a number of bee boxes as well as bee bundles, around the garden in a variety of sites, and these too were very well-used, particularly the nest boxes.

There are innumerable ways to provide nesting sites for these bees, the simplest being to leave snags standing, and to grow plants that bees would use in the wild for nesting. Creating artificial nesting sites is the other option, and ways and means are varied and many.

First and always, when making any bee structure, think of hygiene, as parasites and disease are a serious problem for bees. With simple bee blocks, essentially a wooden cube with holes in it, there are two options: you can replace them every year or you can use removable cylinders in each hole. These can be straws or rolled tubes of paper, which can be discarded when the bees have finished nesting. The bee block can then be disinfected, instructions for which are given in the native pollinator book listed in references below.

Bee blocks work best if they have holes of varying diameters (to accommodate different bee species) and of sufficient depth to allow bees a long tunnel to work in. Some people suggest drilling the holes slightly upward to prevent rain from getting in. Logs with drilled holes can also be used for this same purpose. Old, weathered logs are best as they emulate the snags that bees would naturally use. At the FWG, I’ve noticed bees making nests in some of our old well-worn wooden posts (used for habitat signs) and the split-rail fences.

Other types of simple nest accommodations include bee bundles, which can be made from lengths of hollow stems, such as bamboo, phragmites (abundant in the region, although very invasive so make sure you don’t distribute the seedheads elsewhere), cup-plants. These are best if situated within some sort of cover (large black soft plastic plant pots were used by scientists who set up bee bundles at the FWG in 2012) to protect them from rain and located in a sheltered site. At the FWG, I’ve noticed mason bees checking out plants for nest sites, and they also used the AAFC bee boxes.

Bumble bees frequently nest in the ground, but they will also nest in piles of stones, brushpiles, under decks, and even in bird nest boxes (which I’ve seen several times at the FWG). I’ve also seen them nesting in the foundation of my house and in sheds. In other words, while their sites are varied, what they are seeking is a warm, dry, sheltered cavity.

Finally, some very creative ideas for creating “condos” or “hotels” for bees (and other insects too) come via the Pollinator listserv. These examples show how bee and insect condos can be constructed fairly simply, using found objects, such as plant stems, bricks, logs, etc. Ingenious designs from across Europe are shown, ranging from small and simple to quite large and more elaborate, all of which can be used and adapted for our area. General information about cleaning out bee blocks, and maintaining sites is given, as well as tidbits of other interesting information. Some of the photos show carefully constructed structures that will hold about 8 or 9 separate bee boxes. Others are created with boards or pallets, separated by bricks, and stuffed with a variety of material that will attract not only bees but other insects such as ladybeetles. The site is fun to peruse and is sure to generate a desire to emulate at least one of the structures. At the FWG we are already planning to create several and will be keeping an eye on them throughout the summer to see who uses them.

References:
***Attracting Native Pollinators. Protecting North America’s Bees and Butterflies. 2011. By the Xerces Society. Storey Publishing. I can’t say enough good things about this marvellous book. It provides excellent information, complete with photos, of different types of bee structures, good instructions for how and when to install, how to keep nest boxes and bundles clean, and much more. Buy it!!! It is the best source around; you need no others!

Bee and insect condos and hotels: inspirationgreen.com/insect-habitats.html

NAPPC Pollinator listserv: pollinator.org/nappc/listservrules.htm Provides a variety of topical and worthwhile information with much current information about bees and their conservation and efforts to protect them.

North American Pollinator Protection Campaign: pollinator.org/nappc/index.html The premier site for all things to do with conservation of pollinators.

Pollinator Partnership (NAPPC): pollinator.org/index.html Provides information about all pollinators, with an emphasis on bees.

Xerces Society: www.xerces.org/ One of the best all-round websites dedicated to bees and all pollinators, with a wealth of good, trustworthy information. Check under: www.xerces.org/fact-sheets/ for information on bee boxes.

More references for building bee boxes will be added when I find ones that are suitable.

Leafcutter Bees (Megachile sp.)

By Christine Hanrahan

Megachile constructing nest

As spring very slowly chugs its way into our region, many of us find our thoughts turning, longingly, to gardens and gardening. Those of us inclined to create and maintain gardens for wildlife, are also interested in the various things we can do to enhance our site for birds, bees, and other creatures. Bird boxes, bird baths, squirrel houses, roosting boxes, toad houses, and bee boxes are just some of the things that can be installed to help our fellow creatures. In this article, I’d like to focus on bees, and more specifically, on one type of bee that readily comes to bee boxes: the leafcutter bee in the genus Megachile.

First, a word about accommodation for bees. There are any number of plans for building bee boxes, ranging from the very simple to the extremely elaborate. In another article I’ll talk about the wealth of information available, but here I want to mention one very simple bee box we installed at the Fletcher Wildlife Garden a few years ago and how it attracted a number of Megachile leafcutter bees. Made for us by Bruce Burns, it was initially part of a display we had created to celebrate pollinators. In mid-summer 2009, I installed the bee box on a south-facing post behind the compost bin. A few days later I went back to see if anything might be using it (not really expecting any activity, but what did I know!). To my surprise, I found several leafcutter bees busily investigating the holes in the box. Within a couple of weeks it was very apparent that this bee box was being well used by a number of these bees, and I watched, fascinated, as they carried leaf sections, cut from rose bushes, into the boxes. When an AAFC scientist installed temporary bee boxes at the FWG in the summer of 2012, leafcutter bees were common inhabitants.

The family Megachilidae, typically called the leafcutter bees, includes a variety of genera, but the ones I am especially interested in are those in the genus Megachile. They are very common at the FWG, as indeed, they are throughout this region. Some years before I installed the bee box, while out exploring near Carleton Place, I’d come across nest sites containing a few leafy cells made by Megachile bees, and they were so remarkable that I began looking for similar cells in other areas. Most of the ones I found were under rocks, but they could equally be in rotting wood, in tunnels in the ground, in and around human made objects such as pipes, under bricks, or, as at FWG, in bee boxes.

The bees cut nearly perfect circles from leaves in the Rosaceae family, to construct tubular shaped cells, beautifully formed, and sealed with a leaf circle. In these cells a ball made of pollen and nectar is placed and an individual egg laid on top. A nest site can contain several cells, each closed off with a leaf circle. Some of the ones I have found were newly constructed, the leaves still fresh and green, others old and the leaves dried out. Some had obviously been disturbed by a predator. Some were half buried in the soil, others were jumbled together on top of the soil but under a rock.

I don’t know the exact species of Megachile that made these nests, but two common species are Megachile frigida and M. latimanus (the latter I have photographed at FWG, and the photos were identified to species by an expert). I tend to call all the Megachilid leafcutter bees I see, Megachile sp. These bees are easy to spot, as they carry pollen on their abdomens, instead of in pollen sacs on the legs, as most bees do.

Following are photos of the bees and their nests, including a bee busily constructing her nest. Many of these photos were taken at the FWG.