Ah, early spring! Or, as we know it here on Martha’s Vineyard, the Season of Intense Frustration. Quite routinely in early April, mainland Massachusetts will have sunny days with temperatures in the 60s or even 70s, while we languish under an overcast sky with temperatures 15 or even 20 degrees cooler. It just isn’t fair!
The culprit, of course, is the ocean that surrounds us. At this time of year, all that water is still in the low 40s. Air moving across that water loses heat to the chilly expanse, arriving on the Island scarcely warmer than the water. On the occasional calm, sunny day, heated air rising over the sun-warmed Island leaves low pressure at ground level. Cold air from over the ocean rolls in to fill that gap — a sea breeze — and yet another day that seems to promise 60s peaks around 50 degrees mid-morning.
We can take some solace in the fact that, at the other end of the year, all that ocean water will be a heat source instead of a heat sink. Warmer than the prevailing air, the ocean will prolong our frost-free season deep into the fall, while the mainland shivers. But in the meantime, our early April landscape seems barely changed from how it looked in January.
This year has been especially grim. We did have a few tantalizing, warm days early in March. But by and large late winter and early spring have been overcast, frequently wet, windy, and chilly. Finally, this past weekend we saw a couple of days with sun and temperatures that promised at least a few bugs. And accordingly, I was in the field.
In my experience, finding native bees on the Vineyard is difficult before about the first of April. (Honey bees, which can warm themselves up among their colleagues in a churning hive, are a different story, and can be found foraging on mild days throughout the winter.) Few if any native plants typically bloom this early in the season, so local populations of native bees have no incentive to be active. But the presence of some very early-blooming exotic plants — a new addition to the Vineyard landscape, in evolutionary terms — may be changing that.
Dandelions, for example, have been widely touted of late as a resource for early-season bees. I’m not sure how valid this claim is. Non-native honey bees do visit them with some regularity. But while I occasionally see native bees on dandelions, they seem to be taking only nectar, not pollen; so dandelions may not be much use for the critical task of provisioning nests.
Japanese Andromeda (Pieris japonica) does appear to be a workable pollen source for at least some natives. This exotic shrub, which begins flowering in March, is related to our native blueberry and has flowers that are similar to blueberry flowers in size and shape. So early-season bees that specialize in collecting blueberry pollen (and there are several species) may be finding a season extender in this popular ornamental shrub.
On Saturday, I found multiple Colletes inaequalis (“unequal cellophane bee”) taking pollen off of Andromeda. This bee, probably our earliest emerging native bee species, more typically uses willow, red maple, and sometimes early blueberry flowers as pollen sources.
Also visiting Andromeda that day was a male member of the genus Nomada (I’m still working on a more specific ID). Nomad bees are nest parasites, laying their eggs in the nests of native solitary bees (almost always ones in the large genus Andrena). In most cases, there is a close association of species, with any particular Nomada species parasitizing just one host species. So the presence of a Nomad bee at the end of March, before any Andrena was on the wing, was puzzling.
A visit to Correllus State Forest on Saturday was less productive. With just a few subtle hints of native plants breaking dormancy — for example, hints of green at the center of the dormant leaf rosettes of colicroot, Aletris farinosa — the forest was still weeks away from having flowers. Even willows, often the first pollen source to be available to native bees, held only immature catkins. I couldn’t find a single bee.
Oblique-lined tiger beetles, however, were already common, their black bodies soaking up heat from the sun so they could chase down ants along the fire lanes. Flies, also, were already abundant. Many of the ones I saw were too small and fast-moving for me to hope for a photograph or an ID. But an old friend, the genus Gonia, was active in numbers.
A member of the family Tachinidae, Gonia lays its eggs in early spring on overwintering cutworm caterpillars. Upon hatching, the fly larvae burrow into the caterpillars, developing inside them and eventually killing them. Adult Gonia, meanwhile, visit flowers for pollen (though clearly adults emerge before they have any real hope of finding a flower).
Things will change, of course — gradually at first, then quickly. But for now, only a few hardy and specialized insects are finding what they need on a barren landscape.
