Cellophane bees are very bad at social distancing. In early spring, hundreds to thousands of males and females aggregate on sandy soil and in pines and cedar trees. Males swarm females in large groups termed “mating balls” and, from each cluster, only one male will emerge victorious. Once mated, females get to business building nests. Though solitary, females work in a shared office space called a nesting aggregation for their three-week life. Sometimes, when a female gets bored, she’ll even dip into the nest of another female. Certainly, they do not keep six feet away from each other in the narrow tunnel of the nest. Don’t be like cellophane bees. Practice social distancing.
Cellophane bees are very bad at social distancing. Here, several males have swarmed a female and are competing for the chance to mate with her. PC: Colletes succinctus, Nigel Jones, Flickr
Nevertheless, observing cellophane bees is a great way to social distance while you’re at home and living your best #quarantinelife. In New England, you can find unequal cellophane bees (Colletes inaequalis) nesting in your backyard in late-March/early-April, provided the sod isn’t too thick. Watching cellophane bees be cellophane bees can be a fun distraction. And don’t worry about getting stung since they are quite docile. Here’s a short video to help you get started finding your own cellophane bee nests. If you do find some, take a photo and get in touch! We’d love to hear what you find.
Female cellophane bees nest in close proximity. Each turret of sand marks the entrance to a nest. PC: N. Dorian
It may be hard to imagine finding flowers and pollinators in February, but the first flowers of the spring can already be seen blooming all across New England. Poking up from the frozen ground of swamps and stream banks, skunk cabbage (Symplocarpus foetidus) doesn’t exactly look like your average flower. It produces multiple small flowers on a central spike, or spadix, surrounded by a purplish hood known as a spathe. Few other flowers in northeastern North America share this odd floral structure – a characteristic of plants in the largely tropical Arum family, which includes popular houseplants like Spathiphyllum (peace lily), Philodendron, and Monstera.
Skunk cabbage flowering along a small stream in Massachusetts in late February. Skunk cabbage spathes are easy to overlook, but can be quite common in wetlands in late winter and early spring.
Aside from its bizarre appearance, skunk cabbage stands out from other native New England plants with another unique feature: its flowers have the ability to produce significant amounts of heat! Fueled by energy stored in the plant’s modified underground stem (called a rhizome), skunk cabbage can maintain temperatures of over 50 degrees within the spathe even as external air temperatures drop below freezing. Skunk cabbage flowers produce varying amounts of heat depending on environmental conditions as well as their age. Like some other related plants in the Arum family, skunk cabbage flowers are all female when the spathe first opens. These later become pollen-producing male flowers, with flowers at the top of the spadix transitioning first. Heat production peaks during the female phase, declining as the flowers age and begin to produce pollen.
Skunk cabbage spathe. This structure surrounds the plant’s central flower spike. Its mottled purple color may function to attract carrion-feeding flies that could act as pollinators.
Why does skunk cabbage produce heat? Despite several studies of this phenomenon, the answer is unclear. Production of heat may be necessary to allow skunk cabbage to grow and flower in a rather inhospitable environment, preventing the buildup of snow and ice around the spathe. By flowering well before most other plants, skunk cabbage may be able to take advantage of any insects that are active at this time of year, with heating performing the additional function of attracting insect pollinators. The purplish color of skunk cabbage spathes, in addition to their unpleasant smell, suggests that they may be pollinated by flies. Other primarily fly-pollinated plants share similar traits, tricking flies into visiting their flowers when searching for sites to lay eggs. By heating its spathes, skunk cabbage could provide an extra incentive for these early-season insects to visit its flowers.
Although scavenging flies hardly seem like likely pollinators, they can be quite important to the pollination success of some groups of plants that specialize in attracting them.
While flies have been documented at skunk cabbage flowers, frequency of successful pollination events seems to be quite low. Interestingly, some of the insects most often seen at skunk cabbage flowers are honey bees, which visit male skunk cabbage flowers as an early-spring source of pollen. However, it’s unlikely that honey bees act as effective pollinators, since they tend not to visit skunk cabbage’s nectarless female flowers and may not even make contact with the spadix itself, instead collecting pollen that has fallen to the base of the spathe.
Skunk cabbage provides an excellent example of just how much remains unknown about the ecology of some of our most ubiquitous (and fascinating!) native plant species. As you walk through the woods in late winter and early spring, keep an eye out for this strange plant in any area with wet soil and appreciate the incredible adaptations skunk cabbage has evolved that allow it to thrive at a time when few other flowers dare to bloom.
In summer,
pollinators are not often hard-pressed to find flowers. In fact, you might
support them without even knowing it: community gardens, flowering herbs on
front steps and balconies, or milkweed growing in a tree-well all provide food
for pollinators during the hottest, longest days of the year.
But what about in spring? It’s not as easy to accidentally support pollinators during these cooler months of the year when the ground has just begun to thaw; there haven’t been that many warm days; and persistent rain (as continues this year) can impede pollinators from finding food. Indeed, queen bumble bees emerge from hibernation in early spring and need immediate access to both nectar and pollen in order to start their colonies for the year, and many solitary bees and hover flies are only active for several weeks in spring: no flowers means these pollinators cannot make it.
So, how can you support pollinators in April and May? Think big. Plant native flowering shrubs or trees. In New England, you’ll be hard-pressed to find better forage for insects than these woody plants. Not only do these larger plants produce copious amounts of flowers, but they are often important host plants for caterpillars of moths and butterflies. Plus, with the exception of woodland wildflowers, there simply aren’t enough growing days by mid-spring for most smaller, herbaceous (soft-stemmed) perennials to flower.
In addition to supporting pollinators, serviceberry produces delicious berries enjoyed by both birds and humans. PC: Ryan Hodnett, Wikimedia Commons.
Choose plants that bloom sequentially from April through early-June. By selecting plants with overlapping flowering times, you will support a high diversity of pollinators regardless of when they emerge. To help you decide, here are several hardy options of native trees and shrubs that support bees, followed by average flowering times in Massachusetts:
black cherry (Prunus serotina, late-May/early-June)
red osier dogwood (Cornus sericea, May/early-June)
ninebark (Physocarpusopulifolius, June)
The eastern carpenter bee (Xylocopa virginica) is one of the many native pollinators that enjoy redbud flowers.
Although many ornamental flowering trees are pretty, the frills that we enjoy often do little to help pollinators. Even worse, some ornamental cherry trees sometimes lack pollen and/or nectar altogether, making them essentially useless to flower visitors. In contrast, many ornamental crab apple varieties (Malus sp.), though non-native, are one alternative that appeal to both humans and insects.
Wild cherry trees have five petals per flower, but this “doubled” ornamental produces copious petals (possibly at the expense of quality nectar and pollen) that dissuade pollinators from visiting the flowers. PC: Yoshikazu Takada, Flickr
One last note: to further help early-spring pollinators in a different way, try “leaving the leaves” until early-May. It is tempting to clean up your yard as early as possible, but many insects overwinter as various life stages in the messy leaf piles and ground cover, e.g. butterfly eggs, chrysalises, and adults of different species. Give them a chance to emerge by delaying your clean-up a few weeks. You’ll be rewarded when all these beautiful pollinators return to visit the flowers in your garden!
