Butterfly Bonanza

As we move into July and the weather really starts to warm up, the long grass meadows in our parks are the centre of a remarkable, once-a-year explosion of skipper butterflies.

Skippers, crowding on to a blackberry flowerhead feeding on nectar from the flowers

What these small butterflies lack in size, they more than make up for in the sheer numbers that hatch, take to the air, and adorn almost every flowering plant in and around the fields at this time of year. It’s a spectacle, and one well worth a closer look. The Deer Lake meadows, at the western end of the lake, are a particularly good place to see the action, and enjoy what is by far our largest flight of butterflies in Burnaby.

Purple vetch flowers are a favourite for nectaring skippers

Taking a closer look at these small butterflies, it’s noticeable right away that they’re not quite conventional butterfly shape. To some people they suggest moths, rather than butterflies. Their wings are more “swept-back” instead of being held either flat and open, or upright and closed, like “regular” butterflies. The hind wings are held out flat, while the forewings are held above them at a 45-degree angle – very rakish! They do at times, however, close both wings over their backs like regular butterflies. As you can see from the pictures, the open-winged stance is very common. This distinctive shape and stance shows that these butterflies are members of the grass skipper family.

Skippers feeding (nectaring) on a dandelion – click to enlarge

So let’s take a close-up look. When you click to enlarge the photo above, you’ll see a couple of good clues as to why these insects are butterflies, and not moths. First take a look at the antennae which emerge from the head, angling outwards. They’re thin and thread-like with noticeable, club-shaped ends. In contrast, many moth antennae are feathery, and if they are thin like a butterfly’s, they lack the club end. Most moths are, of course, nocturnal, whereas these “guys” are active in the daytime. Two ticks for butterfly.

Now take a look at the skipper on the far right on the dandelion. You’ll see a third, thread-like organ emerging from the centre of the head, which then makes an angular curve downward into the flower. This is the proboscis, the hollow tube through which the butterfly draws up the nectar on which it is feeding. Now that you’ve looked at one skipper, a quick glance reveals that they’re all at it. This single flower is feeding a whole bunch of skippers.

Skipper Profusion

So what species of skipper are these? Well, thereby hangs a tale. These are European skippers. That’s right, they’re an introduced species from Europe.  First accidentally introduced to Ontario in 1910 they’ve spread across the country, and there have been many subsequent introductions since, including Duncan on Vancouver Island about 15 years ago. Ours could have spread from there, or they could have been introduced here separately. A particular aspect of the European skipper’s reproduction makes spreading to new locations very easy. And as usual, it’s we humans that are big contributors to skipper profusion, and skipper spread.

Unlike all native species of North American skippers, which overwinter as pupae, European skippers overwinter as eggs. This makes it very easy to survive being mowed, and then moved when hay is transported from one place to another. And hay fields is where skippers thrive. They’re called grass skippers because the larvae, the caterpillars, feed on grasses. As we can see, the adults get their food from flowers.

European skippers feeding on clover

Although an introduced species, the European skipper is yet another example of a benign addition to our fauna. In this case, a very beautiful one too. There is no evidence that this introduced skipper has negatively affected our native skippers. It seems to have found a place here without causing problems for other species.

As John Acorn says in Butterflies of British Columbia  … we now have more butterflies on the wing than we ever could have without this cute little addition to our fauna. Here, here!

European skippers – a welcome addition to our butterfly fauna