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By Amy Melissa Witt

Did you know that an average garden could hold 2000 insect species, most of which are beneficial?  Unfortunately, the numbers of insects are declining primarily due to habitat loss and pesticides. 

Insets have very important roles:

• They eat pests.
• They are pollinators (beetles pollinate 88% of all flowering plants, more than any other animal). 
• They contribute to the ecosystem.
• They are a critical food source for birds.  According to a recent study done at the University of Basel in Switzerland, the world’s birds eat 450 to 550 million tons of insects each year. 

One way to help protect insects and preserve their habitat is to create insect hotels.  Insect hotels provide safe areas for insects to hibernate during the winter.  They are created with found or upcycled materials and consist of rooms designed to meet a variety of insect habitats. Rooms are filled with natural, non-toxic and stable recycled items (pieces of clay plant pots, large pine cones, wood, bricks, straw, bamboo stakes, etc.).  Many materials can be found in your own backyard, gardening shed, and local transfer or recycling centers. 

Benefits of insect hotels:

• Encourage beneficial insects to help control pests.
• Stimulate biodiversity and ecological balance in the landscape.
• Structures replicate natural habitats, provide space to create nests over the summer (including beetles, May flies, hover flies, spiders, and green lacewings) and hibernate in winter (including bees, moths, butterflies, and ladybugs).  Some insects will live 9 months in a hotel.

Creating an Insect Hotel

Container

• Container needs to be open at one end closed on the other in order to hold filler (baskets, wooden boxes, small galvanized buckets, clay pots all work great).
• Pre-roll leaves and paper, glue one tube in place as cornerstone, add glue to other materials as needed.
• Put smaller containers inside large ones.
• Create curves, circles and layers.
• Pack materials in tight enough to stay in place, but not too tight that insects can’t get in.
• Sand the front as splinters can catch on bodies and injure insects.

Materials

• Bamboo, hollow plant stems, rolled newspaper (different diameters attract different species).  Keep in mind that narrow tubes are more popular than wide ones.
• Cardboard – use to make or hold small tubes, corrugated cardboard has the extra advantage of small holes. (Lacewings are huge consumers of aphids and like rolled up cardboard.)
• Pine cones attract ladybugs.
• Bark and dry leaves are used by many insects.
• Straw/hay is a great insulator for hibernating insects; hollow with different lengths & widths bundled together is best.  Straw can also be used as filler.
• Ornamental grass creates tunnels, provides texture, and different sizes can accommodate many insects.

Placement

• Hang the structure 5’ off ground and secure it so doesn’t shake in wind.
• Place in a sheltered, warm space, with dappled shade, surrounded by variety of flowering plants. 
• Protect from birds. Some birds, like woodpeckers, attack blocked up holes looking for larvae to eat.  Cover the front with chicken wire/hardware cloth if birds are around the hotel.

Hotels for Native Bees

• There are over 270 native bees in Maine.
• 30% of native bees make nests in old beetle tunnels in tree snags or similar locations.
• Most native bees need a hollow tube to a make nest.
  • Need different hole sizes for different bees (leafcutter bees – ¼” wide and 2 ½ to 4” deep; mason bees – 6” deep 5/16” wide)
• Use pieces of branches or lumber to make hotels.
  • Mix diameters, drill in on a slightly upwards angle so holes don’t fill with rain water, being careful not to drill all the way through (will create a wind tunnel).  Be creative and drill holes in patterns.
  • Vary hole sizes from ¼ – ½” in diameter, space holes at least ¾” apart.
    • Holes less than ¼” diameter should be 3-4” deep; holes larger than ¼” should be 5-6” deep.

Placement

• Bee hotels need to be placed high enough (3-6’) off the ground to keep away larvae eating ants.
  • Hang in sheltered, sunny spot (not direct sun), and make sure it is level.

By Amy Melissa Witt

Best inflorescence types for beneficial insects:

Umbels – umbrella-like clusters (Dill, Queen Anne’s Lace, Angelica, Fennel, Yarrow)
Composites – tiny center flowers, surrounded by rays (Sunflowers, Daisies, Coneflowers, Cosmos)
Spikes – group of flowers arising from main stem (Lavender, Goldenrod, Hyssop)
Cups – (Evening Primrose, Buttercup)

Plants
Below is a list of some of the best plants for beneficial insects. Include as many of these plants as possible in your garden to attract, encourage, and support a broad diversity of beneficial insects.  In addition to planting these plants, always allow your garden to stand through the winter months so beneficial insects have a place to overwinter.

Black-eyed Susan – Rudbeckia species
Boltonia – Boltonia asteroides
Common Boneset – Eupatorium perfoliatum
Cosmos – Cosmos bipinnatus
Culver’s root – Veronicastrum virginicum
Dill – Anethum graveolens
Goldenrod – Solidago species
Hardy Aster – Symphyotrichum species
Meadowsweet – Spirea alba
Mountain Mint – Pycnanthemum species
Shasta Daisy – Leucanthemum x superbum
Sunflower – Helianthus annuus
Sweet Alyssum – Labularia maritima
Tickseed – Coreopsis species
Yarrow – Achillea millefolium