Seed and plant specialist Barbara Schaefer explains in her blog how to make a habitat for pollinators - using the example of the sweat bee:
"In early spring, insects are still in diapause (a state akin to hibernation). They are triggered to wake up when the weather warms and/or the day-length increases. Cutting down dead plant stems too early in the spring will disturb them before they have a chance to emerge."
Prevailing knowledge said it was a sign of good gardening to have a tidy garden, providing fewer places for unwanted pests to overwinter. Turns out that I was dead wrong."
"My gardens are not only for my enjoyment and satisfaction but also home to insects that pollinate my plants and whose larvae feed nestlings of songbirds. As a steward of the land, I have a large role to play in my small part of the world".
I have learned that some butterflies overwinter as adults. They nestle into rock fissures, under tree bark, or in leaf litter until the days grow longer again and spring arrives. Other butterflies overwinter in a chrysalis, either found hanging from dead plant stems or tucked into the soil or leaf litter. And still, other butterfly species spend the winter as a caterpillar rolled into a fallen leaf or inside the seed pod of a host plant.
Predatory insects may also spend the winter ‘sleeping’ in my garden as either adults, eggs, or pupae. They are one of the best reasons not to clean up the garden in the fall because they help control pests. If I want to have a balanced population of predatory insects, I must provide diverse winter habitat.
Some insect-eating birds have not flown south for the winter. They are quite good at gleaning ‘hibernating’ insects off dead plant stems and branches, and out of leaf litter (when it’s not buried in heavy snow). Not cleaning up the garden means there will be more protein-rich insects available to them during the coldest part of the year. The more insect-nurturing habitat I have, the greater the bird population will be. Further, seed-eating birds will appreciate the seeds and berries they can find on intact perennial, annual, and shrub stems.
Read her eye-opening blog post here:
https://gardensbybarby.ca/gardening-for-pollinators/