As the weather starts to warm in April, one of the first and most obvious groups of insects to become active are the bees. The earliest species are already on the wing; in the coming weeks, dozens more will join them, visiting flowers and making nests in an astonishing array of settings.
Generally recognizable by their hairy bodies and legs and their persistent interest in visiting flowers, bees have enjoyed a burst of favorable (though sometimes misleading) publicity over the past few years. The message on bees has had two main parts: first, these insects are vital because of their role in pollinating flowers, and second, bee populations appear to be in widespread and rapid decline.
Both points are true, and to them I’d add that as a group, bees include some of the most attractive insects and also some of the most interesting biology to be found in the insect world. These are creatures worth observing and worth learning about.
The first thing you should know is that the species everyone is most familiar with — the honeybee — is only one species among many (more than 180 species have been documented on Martha’s Vineyard). Moreover, the honeybee is not native to North America. Fascinating insects in terms of their complex behavior and social structure, honeybees also play an important role in agriculture, fertilizing the flowers of many food crops.
However, research has shown that honeybees are not effective pollinators for many native species. They’re most effective pollinating flat, open flowers (think of an apple blossom); when visiting deep, narrow, or tubular blossoms, honeybees often don’t come in contact with the flower’s reproductive organs and hence don’t transmit any pollen.
A growing body of evidence suggests that honeybee populations, because of their remarkable social coordination, compete aggressively for pollen and nectar against native bees, and as a result, under some circumstances at least, can reduce the ability of native species to reproduce. Most entomologists I know appreciate the fascinating biology of honeybees, their docile nature, and their economic value. But they’re not interested in seeing honeybee populations increase in natural settings.
My interest, then, is much more in the native bees, and there are plenty of them to study. The earliest species on the Vineyard can be found in late March most years, and bee activity continues until we’ve had several hard frosts in mid- or late November.
While your notion of nesting bees might be a humming hive of hundreds, in fact the vast majority of our bees are so-called solitary ones: Instead of living in a crowded, communal nest, each female builds her own nest and tends only her own eggs.
The methods bees use for nesting are varied. Carpenter bees, famously, chew into wood (sometimes, unfortunately, the wood of human-built structures), laying their eggs in chambers branching off a long gallery. Other species use naturally occurring cavities, such as hollow stems. Perhaps the majority of our native bees, though, nest in burrows dug into the ground.
Lately it has become popular to erect “bee houses,” made of bundles of hollow reeds, in an effort to support bee populations and attract bees into the yard. Sometimes these work well. But as is often the case, intervention in nature can produce unintended consequences. A major peril bees face is attachment by nest parasites: Other insects that lay their eggs in bee nests, with the parasite’s young eating either the bee larvae or the pollen the adult female has stored for her offspring.
Under natural conditions, pollinators must search laboriously for each bee nest they attack. But if a parasite comes across a bee house with large numbers of bees nesting right next to each other, the job becomes too easy. Multiple bee nests can be parasitized at once, increasing the impacts on bees and producing a large next generation of parasites.
I wouldn’t actually discourage bee houses. But I’d urge people to try to see what actually emerges from the nests (bees or parasites). And I’d consider trying to encourage bees by other methods that more closely mimic natural conditions (leaving portions of your yard unmanaged, for example, with uncut shrubs and pithy flower stems for bees to nest in, or ensuring that your yard includes some bare soil).
However you choose to encourage bees, attentive observation will show you surprising diversity no matter where you live on the Vineyard. The bee world is well stocked with colorful species (iridescent green figures prominently in several important bee genera, and some species have gaudy striping or patches of red or orange). Despite the general rule of hairiness in bees, a few groups have evolved back into nearly hairless insects. These so-called “cuckoo bees” don’t need hairs because they don’t gather pollen. Instead, they lay their eggs in the nests of other bees (ranking them among the nest parasites I discuss above).
Best of all, bees will come to you! Diversity may be highest in natural settings. But regardless of their life histories, adult bees of all kinds love a nice flower. Ornamentals or even just “weeds” in your yard will bring these insects in for a visit. So these insects are not just useful and fascinating, they’re easy to observe.