Little information is available for building insect hotels that are successful in attracting their intended residents. If the goal is simply ornamental garden art, there are fewer constraints, but why not install a hotel that meets both criteria? Following are a few tips, and a list of helpful resources. Providing habitat for local bee populations, in particular, becomes increasingly important as we understand more about the benefits of pollinator biodiversity.
Insect hotels range from simple drilled bee blocks to elaborate architectural structures, from the primitive to the sophisticated, and from the practical to the artistic.
Successful insect hotels should include generous sections for nesting bees and solitary predatory wasps; we know little about the use of hotels by other insects. However, insect hotels also provide an opportunity for artistic expression and for experimentation with variations in materials and designs that might work in a particular environment.
The most well-known artificial native bee dwellings that are known to work are simple wooden blocks drilled with holes (see Attracting Native Pollinators in the resource list for instructions on specific diameters and depths). Hollow stems also work well; leave a node at one end to provide a “back wall.” The stems of fennel, elderberry, bamboo, brambles, teasel, and many members of the buckwheat family (Polygonaceae) are all suitable. Stems of approximately the same diameter (and about 5-6″ long) can be tied in bundles or packed into cans, pipes, or other objects and used either singly or incorporated into larger structures. Wet clay or drilled dry clay blocks can be added to insect hotels, and will attract a variety of hymenoptera. Sections of branches in which beetles have tunneled can also provide native bee habitat.
Other materials suitable for experimentation includes lichen, straw, bark, twigs, leaves, pine cones and other organic materials. Lacewings and other insects may hibernate in rolled-up corrugated cardboard. Provide a diversity of materials and then observe which are serving as nesting sites. Gardens are ideal laboratories for observation. Be sure to use dry materials, especially in damp or foggy areas.
Build Insect Hotels
A hotel can be fashioned from a simple box or can, or designed as an elaborate structure requiring the services of a professional builder. Regardless of size, the hotel must be firmly attached to its base, and level. Protect the hotel from the primary storm direction by placing it under an eave, or providing a sheltering roof. Position hotels to receive morning sunlight; east or southeast positions are best. West-facing hotels may get too hot for most insects. If more than one hotel is being installed, experiment with locations and observe the different species each hotel attracts. A hotel installed in cool, damp, semi-shade will attract different residents than will one placed in a hot, dry site.
In addition to nesting sites insect hotels, other habitat resources should be included in gardens. A source of water, overwintering sites, and shelter from the wind are important in attracting a diversity of beneficial insects. Areas of bare ground are critical habitat for many native bees; areas of wet clay provide a resource of mud nest-building predatory wasps and for “mud-puddling” butterflies. Brush and leaf piles, and bunch grasses are all attractive to overwintering insects; trees with loose or fissured bark provide winter shelter for butterflies and other insects.
Beneficial insects also require flowering plants; besides bees and other familiar pollinators, many predatory insects use pollen and nectar as food in their adult stage, feeding live prey only to their larvae. Plan for a succession of bloom in the garden, and choose flowers with accessible nectar and pollen, such as plants in the daisy, carrot, mint, and mustard families. Bunch grasses are an important source of early season pollen for many insects. Other good choices are members of the rose and buckthorn families and native wildflowers; include a high proportion of locally native plants for best results.
“Layers” of forbs, grasses, shrubs, and trees create microhabitats, even in a designed landscape, and promote insect biodiversity. Layers also provide homes for alternate prey-food sources for predatory insects that will keep them in the area once they have eaten all their favored prey on desirable garden plants. Many insects (eg, butterflies) are associated with particular species of larval host plants that can be incorporated in the garden. The base of an insect hotel is an ideal site for accommodations for frogs, toads, and lizards. A certain amount of “messiness” in the garden, especially in winter, also encourages insects to stick around; let natural leaf mulch build up under native trees and shrubs, and wait to cut back perennial plants.
Maintaining Insect Hotels
Insect hotels require maintenance for success, as some diseases and pests, such as mites, can build up after a few years. Some hotel builders advocate completely changing the filler materials every two years, or sanitizing drilled wooden blocks. Native bees will appreciate the use of straw liners or rolled-up parchment paper liners in the drilled blocks. Many pest and disease problems can be reduced by making small, disposable homes, but place new ones in the same location for insects that use the same site year after year.
Argentine ants can be controlled with borax preparations applied at the base of an insect hotel. If woodpeckers become a problem (some authors suggest that an “insect hotel” could be easily become a “woodpecker restaurant”), consider installing a chicken wire barrier around the hotel.
For Further Research
Attracting Native Pollinators: The Xerces Society Guide to Protecting North America’s Bees and Butterflies. North Adams, Massachusetts: Storey Publishing. 2011. Principally focused on bees and butterflies, including detailed instructions for creating artificial habitats for bees.
Dewees, Jason, and Lisa Lee Benjamin. A Manifesto for the Urban Hedgerow. Pacific Horticulture, April 2011.
Gunzël, Wolf Richard. Das Insectenhotel. 2007. This book may require the kind assistance of a German-speaking friend
Lavoipierre, Frédérique. Garden Allies, a series of columns appearing in Pacific Horticulture. Available online at http://www.pacifichorticulture.org/garden-allies/
Moisset, Beatriz, and Stephen Buchmann. Bee Basics: An Introduction to Our Native Bees. A USDA Forest Service and Pollinator Partnership Publication, 2011. Available online at: http://pollinator.org/PDFs/BeeBasicsBook.pdf
The Melissa Garden, a honey bee sanctuary in Sonoma County, California: www.themelissagarden.com.
Sonoma State University, Entomology Outreach Program lists sites with publicly accessible insect hotels and additional information on habitat gardens and plants for beneficial insects: http://www.sonoma.edu/preserves/education/entomology.shtml
UC Berkeley’s Urban Bee Garden: http://nature.berkeley.edu/urbanbeegardens/
The Xerces Society. The society’s mission is insect conservation; they offer numerous publications and information on their website: www.xerces.org
Wildlife stacks: similar to insect hotels, they are used as overwintering habitat for insects and other wildlife in the British Isles http://www.rspb.org.uk/advice/gardening/insects/wildlifestack.aspx
An insect hotel architectural contest: http://www.detail.de/artikel_arup-associates-international-year-of-biodiversity-design_26278_En.htm
Mason bee block instructions: http://snohomish.wsu.edu/mg/ombblock/paper%20liners%20that%20work.pdf
RS Duckworth~Design/Construction. Large-scale insect hotels (and other wildlife habitats) created in consultation with a biologist with expertise in beneficial insect habitats. www.rsduckworth.com
http://www.flickr.com/groups/insecthotels/pool/ A rich source of ideas and plans for insect hotels.
To read the author’s full story about Insect Hotels for West Coast gardens, click here to purchase a copy of the April 2012 issue of Pacific Horticulture.