Trees for Pollinators

Trees for Pollinators!

By Amy Yarger, Senior Director of Horticulture

When we think of gardens that support pollinators such as butterflies and bees, we often think of flower beds and sunny meadows. However, with over a thousand species of bees in Colorado and the countless flies, beetles, moths, butterflies, and wasps that pollinate plants, habitat can be as diverse as these important insects are. Pollinators not only move pollen from one flower to another but have other interactions with plants in their environment. Some pollinators are leaf chewers during their larval stage or spend part of their life cycle nesting inside plants. Others are predators or parasites of plant-eating bugs. And most insects use plants or plant material for shelter, whether that is pupating under leaf litter or roosting on a protected branch. For that reason, plantings for pollinators should feature a diverse selection of native plants, including woody plants such as trees and shrubs.

If you are considering planting a tree in your landscape, this is the time of year to do it; the temperatures are mild, and moisture is readily available. Here are a few recommendations for trees that have special relationships with local pollinators.

Prunus virginiana and Prunus americana – Chokecherry and American plum – These early spring bloomers provide festoons of pale fragrant blossoms which feed many bees, butterflies, and flies, but they also are hosts for swallowtail butterflies and the magnificent Weidemeyer’s admiral (Limenitis weidemeyerii).

Amelanchier alnifolia – Saskatoon serviceberry – This small tree is also an early spring bloomer and larval host for swallowtail butterflies. Their berries are also great food for birds.

Gleditsia triacanthos inermis – Thornless honeylocust – Honeylocusts and other related trees provide larval food for the silver spotted skipper (Epargyreus clarus) and thrive in our climate extremes and heavy soil.

Quercus spp. – Oaks – Oaks have been celebrated for the hundreds of caterpillar species they feed, especially in other parts of the country, but they also are a key habitat tree here for the shelter they provide. A special tree shout-out goes to our native shrubby Quercus gambelii, or Gambel’s oak, which is the host for our state butterfly, the gorgeous Colorado hairstreak (Hypaurotis crysalus)

Celtis occidentalis – Hackberry – This species is another tough tree for our prairie climate, provides berries for birds, and also hosts for the American snout (Libytheana carinenta), mourning cloak (Nymphalis antiopa), and the question mark (Polygonia interrogationis). This tree species doesn’t look like much when small, but they mature into stately shade trees.

Some of the other key woody plants for pollinators, such as cottonwoods and willows, are harder to manage in smaller home landscapes, but we can advocate for them in natural areas where they provide resources for many kinds of wildlife, including pollinators. Butterflies such as the beautiful mourning cloak feed on cottonwood leaves as caterpillars, while many bees rely on the pollen of willows early in the spring.

Trees provide so many benefits to our landscape – they provide shade and shelter, cool our urban areas, feed people and wildlife, and even provide recreation if you are a climber. It’s nice to know that we can enjoy both pollinator habitat and trees to make our landscapes better for people and other living things.