Lepidopteran Pollinators & the Proboscis

So I've talked about various types of bee pollinator, fly pollinators, and even wind. But I haven't talked much about Lepidopterans (butterflies).

Today, while out enjoying the weather in the wooded portion of the Notre-Dame-des-Neiges cemetery, I encountered a couple of common butterflies that, unusually, held still long enough for me to photograph them, so I'm going to take my opportunity to talk a little bit about this group of pollinators.

First up, we have the very common Glaucopsyche lygdamus couperi ('Silvery Blue' butterfly), a native of North America with a fairly broad range [1] which you have probably seen before:

Glaucopsyche lygdamus couperi - this individual very obligingly held still for me so I could get a few photos

 Lepidopterans tend to be nectar-feeders, so plants that have co-evolutionary relationships with them will generally produce it in reasonable quantity. They are not as efficient at pollen transfer as bees, as their bodies tend to be lifted up on long legs that prevent the extensive physical contact that we often observe between bee and stamen. Nevertheless, they are valuable and effective pollinators.

Glaucopsyche lygdamus couperi on Vicia cracca (cow vetch) - this is what the underside of the wings looks like

Lepidopterans have one piece of handy equipment that other pollinators do not: a proboscis. The proboscis is a tubular mouthpart that serves essentially as a straw. It varies in length depending on species and, in the case of the longer ones, can be extended or coiled as needed.

So if you're a plant that would benefit from attracting butterflies and excluding other pollinators (perhaps in order to devote your resources to a single, more loyal species rather than take your chances with more fickle visitors), what kind of structure is most suitable? A deep nectar spur (pocket where nectar is produced and stored) that can only be accessed with an insecty straw, of course! So the more exclusively Lepidopteran-pollinated a species, the more likely it is to have a long nectar spur which can only be accessed via proboscis.

I got a fantastic shot of the very common Poanes hobomok ('hobomok skipper' butterfly) using its proboscis to suck up some nectar from Vicia cracca (cow vetch):

Poanes hobomok collecting nectar from Vicia cracca

Poanes hobomok, like G. lygdamus couperi, is native to this region and also very common [2], so it's very likely you've seen one of these before.

Of course, Lepidopterans can and do get nectar from a variety of flowers, many of which aren't specialized exclusively to them, such as Vicia cracca (cow vetch). This introduced species is originally native to Europe which is now broadly distributed in North America (range map here). It is listed as invasive but with low current threat status in Minnesota [3]. Apparently the spread of this species is also leading to a range expansion for the native Lepidopteran G. lygdamus couperi [1].

Vicia cracca

The peas produced by this plant are edible [4] though in my experience not that tasty (starchy, bland).

Vicia cracca

The USDA forest service has a little blurb page about butterfly pollination for those interested. And, a bonus picture:

Poanes hobomok on Vicia cracca

Cow Vetch - Vicia Cracca

V. cracca flower stalk and fern-like leaves

This is my specimen photo of cow vetch (fr. vesce craque, pois à crapauds), vicia cracca. It is a very hardy, invasive plant, considered a weed where it isn't native. Though it isn't native to Canada, in this environment it isn't particularly problematic. Cow vetch, being a meadow flower, has limited scope in a mostly wooded area like the one where I photographed this plant. It can be problematic as an invasive plant, but it is an excellent fixer of nitrogen, so it's not entirely bad, either. The difficulty with this plant is in its tendency to spread aggressively, choking and eventually squeezing out other plants.

V.  cracca flower stalk

I love the shape of the flower; it looks a bit like a rabbit's head to me. I love the way the deeper purple veins in the upper petals are clearly visible here, in their double-loop pattern. Cow vetch is particularly attractive to bees and butterflies, so sticking around these for a while results in quite a show.

I took a stroll this morning with my father to identify two shrubs, the berries of which seem to be particularly attractive to birds; yesterday, we spotted a cedar waxwing on one of them. This area is mostly too dense and forested for cedar waxwings, so it was a nice sight. The plant that attracted it was a red elderberry (fr. sureau rouge), sambucus racemosa.

Also, my parents adopted kittens recently. They're brothers, and close to 4 months old now. Here's a picture of them spooning. Just for the cute.

Leo (orange) and Noirot (black)