As I've mentioned before, July 4th is high butterfly season. Among the butterflies flying at this time are many hairstreaks. Hairstreaks are colorful little butterflies that I find interesting to look at. I really like them and look forward to seeking them out at this time of year.
So it should be no surprise that I've been out chasing butterflies recently. One place I go is the Great Blue Hill Reservation in Canton. The hill is an interesting place to look in part because it's a hill. It is 635 feet high, not real big, but big enough to be interesting.
Hills are interesting because they can create little local climate effects. One such effect is wind on a hot day. Hot air rises, but it is also helped along by blowing up the steep slope of the hill. This isn't very welcome if you're trying to take pictures of little butterflies blowing in the wind.
But the elevation of the hill has another effect that the butterflies find attractive. While walking up this hill in the 95 degree heat, I was seeking out milkweed plants. Butterflies love milkweed with its large flower heads full of rich sugary nectar. At the bottom of the hill the plants were already past peak and fading. Not many butterflies on them. Gradually moving up the hill, the plants began to be at peak. Many butterflies, banded hairstreaks, Edwards' hairstreaks and coral hairstreaks just to name a few. I stopped many times on the way up to try to capture photos.
At the top, much of the milkweed wasn't even in bloom yet. What a difference a few hundred feet make. These butterflies are pretty smart, taking advantage of the extended milkweed season that the hill provides.
While the hilltop milkweed had yet to open, Canada thistle was in bloom. It is also rich in nectar so there was plenty to attract the butterflies on the hilltop. The greatest concentration of hairstreaks was on the thistle. In addition to the butterflies I'd seen on the way up, I also found striped hairstreaks and an unusual white M. The white M was special for me, I'd never seen one before and they are uncommon to find.
I can't say why white M butterflies are uncommon. They like oak environments near openings with flowers to nectar on, like the top of Great Blue Hill, so there's plenty of habitat around. But we are at the most northern extent of its range, so perhaps it doesn't like our cooler climate. It is uncommon enough that I was thrilled to see it and it made my day after the long hot climb.
I also spotted a monarch butterfly laying eggs. I'd seen one on the way up laying eggs on milkweed, its favorite food plant for its caterpillars, and I'd tried to photograph the egg. Needless to say butterfly eggs are tiny and not easily photographed.
The butterfly on the top of the hill had laid an egg on a black swallowwort leaf. I'd heard about this; this wasn't good. Black swallowwort is a non-native invasive plant infesting the hilltop. Among other undesirable behaviors, it's killing the thistle that the butterflies use for nectar. Black swallowwort is a vine-like plant that's proven very hard to control and it's spreading.
Perhaps the most alarming problem with black swallowwort is that monarch butterflies think it's a good plant for their eggs. Unfortunately this is not the case. When the caterpillars hatch out they don't grow well on black swallowwort and often die before reaching the next life cycle stage. Not good.
However this egg represented another opportunity for a picture. Unlike adult butterflies, eggs haven't yet developed shyness. So I had a nice stationary, but teeny, subject. I'm interested in butterfly eggs because, if you can get close enough, you can see that they have fine detailed structure. Different butterflies have differently shaped eggs. The monarch egg is kind of a domed cone with fine little ridges. Unlike some other butterfly eggs, monarch eggs aren't around for long. They hatch out into caterpillars in only a few days, so they're not something you see every day.
While I spent my time on the Great Blue Hill chasing butterflies, the Reservation has many attractions. There's an Audubon Visitor Center with a small zoo at the bottom of the hill and a weather observatory at the top. The reservation is extensive with miles of trails, vistas of Boston, many habitats and even a boardwalk through a bog. If you've never explored the Great Blue Hill, it's a place I can recommend.
The hummingbirds at Broad Meadow Brook are continuing to grow. The two chicks are developing feathers already and are growing at such a rate that they may fledge from the nest before my next opportunity to visit with them.
Higher resolution copies of the butterfly photos shown here as well as a few additional pictures can be found in my online gallery.