rapidly become choked with invasive plants that unfortunately aren’t serving wildlife the way we might imagine. Nesting habitat isn’t rocket science – the basic needs of pollinators can be met fairly easily – but sometimes we need a bit of a mentality shift and thoughtful attention to what’s happening both above and below ground, in both crop and non-crop areas.
BEYOND FLOWERS:
ON-FARM HABITAT TO SUPPORT POLLINATOR NESTING & OVERWINTERING by Sarah Foltz Jordan
PHOTO: CERATINA BEE ON A RASPBERRY BLOSSOM. CREDIT: SARAH FOLTZ JORDAN.
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hen considering habitat for pollinators, there’s a (very understandable) tendency to focus on flowers. Flowers provide essential pollen and nectar for bees and other insects, and also add vibrant color and beauty to our farms, yards, and community spaces. However, flowers alone aren’t enough to meet the basic needs of pollinators. In order to help insects to build and sustain successful populations in our agricultural landscapes over the long-term, we also need to provide shelter for these animals, specifically by increasing the availability and quality of their nesting and overwintering habitat. So, where do insects make their homes? Given the astounding diversity in insects (even within “pollinators” and other more-narrow groupings), the answer isn’t simple. Together, the US & Canada are home to nearly 3,600 species of bees and roughly 12,400 species of parasitic and predatory wasps, each with their own unique morphology, habitat requirements, and highly sophisticated life history. That said, there are a few running themes that are useful for farmers and other land stewards to know about. Most bees and solitary wasps in our region create small nests
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Here at Xerces, we have recently developed a short guide – “Nesting and Overwintering Guidelines for Pollinators and Other Beneficial Insects” – focused on a variety of natural nesting habitat features that can be readily incorporated into most landscapes. For farms, I’ve distilled our recommendations as follows (but feel free to check out the full guidelines online for additional details): •
Ensure your farmscape includes a diversity of species that are known to provide resources for nesting (see Tables 1, 2, & 3 in this article for ideas). For example, an abundance of native bunch grasses can help ensure ground-nesting bees have access to undisturbed soil. Wild roses (Rosa), maples (Acer), basswood (Tilia), and juneberry (Amelanchier) provide leaf-tissue for leaf-cutter bees to use to line the cells of their nests. Pithy shrubs like elderberry (Sambucus), highbush cranberry (Vibernum), and raspberries (Rubus) make fantastic homes for stem-nesting bees, as do some of our wildflower stems like bee balm (Monarda) and hyssop (Agastache). A few plants that are often thought of as weedy or worthless, such as box-elder (Acer neguda) and sumac (Rhus), are actually quite valuable for bee nesting. While you might not go out of your way to plant these more common species, you may wish to prune them occasionally to increase nesting, and make sure that they aren’t exposed to pesticides or other broadscale disturbances.
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Establish native insectary strips in crop fields or edges to benefit ground-nesting bees, ground
at varied depths beneath the soil. Others nest within dead plant stems or branches, often having preferences for those that are hollow or pithy enough for the insect to chew into. Some bees and many other insects find or build cozy cavities within tree snags or logs, with different insects settling in and moving out as the wood transforms through various stages of decay. Still other insects such as butterflies, fireflies, lady beetles, and ground beetles seek shelter in places that offer protection from predators and the elements, such as leaf litter and piles of rock or brush. Similarly, bumble bee nests are often found under brambles, tall grasses, brush, or rock piles, often associated with an abandoned mouse nest. Unfortunately, manicured farms and yards rarely leave enough of these “messy” habitat features to support robust populations of pollinators and other wildlife. Farmers who do have these features often feel bad (rather than good) about it – the way you might feel about a mess you haven’t gotten around to cleaning up yet. Conversely, farmers might feel a little too good about the amount of noncrop “wildlife” areas on their farms, failing to notice that without attention and management, these areas have
