In my region of central North Carolina, it has been a very sparse year for butterflies and moths. The local lepidopterists (folks who study this group of insects) suspect that an especially severely cold winter followed by a wet early spring may be responsible for the dearth of this insect group. This is not just bad news for those of us who enjoy watching colorful butterflies drift in clouds from flower to flower. It is very bad news for the ecosystem, because myriad species of animals — most especially nesting birds — rely exclusively on the larvae of this group (caterpillars) to feed their young. Caterpillars are the perfect baby bird food — packed with protein and other key ingredients that insure that chicks grow quickly to fledgling stage, where they become less vulnerable to predators. In fact, caterpillars are the only food parent birds of familiar species such as Eastern Bluebird, Carolina Chickadee, and Carolina Wren can use; their chicks require the specific nutrients in those proportions to grow and fledge.
The well-known classic, Silent Spring, by Rachel Carson warned the world about what happens when insects disappear from ecosystems. The banning of DDT saved our birds that time. A more recent classic, Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens, by Douglas W. Tallamy, details specifically which species of insect rely on which species of native plants. The list is long and alarming — at least to me — because many species of insects rely exclusively on only one species of plant to feed their larvae. If that plant species is unavailable, the insects that rely on it cannot complete their life cycles. If the host plant species becomes widely unavailable (as species of Ash trees are becoming now, due to devastation by the non-native Emerald Ash Borer), insects that rely on those species will disappear.
I was delighted to spot this fresh-looking Juniper Hairstreak dining on Swamp Milkweed in my pollinator garden yesterday. This small butterfly is often overlooked, because of its soft green color, but it is relatively common in the Piedmont region of North Carolina because its larval food plant — Eastern Red Cedar (Juniperus virginiana) is also relatively common. On my five acres, we are lucky to have a number of 40-foot mature specimens. They provide shelter for birds and other creatures, their bluish “berries” (actually cones) are beloved by Cedar Waxwings and other birds, and their sturdy shade and deep green color make this evergreen species well-suited for any landscape. If sited where air flow can stagnate, a colorful fungus that uses this species as an alternate host can appear, but I solved this issue in my yard simply by limbing up the trees to permit better air circulation.
References tell me that male Juniper Hairstreaks linger on branch tips of their host tree until a female is attracted. Females lay single eggs on the tips of branches, which eventually hatch to become very well-camouflaged caterpillars similar to the one in this link. I’ve never seen one on my trees, but then again, I’ve never gone looking for them either.
But the presence of this fresh-looking specimen on my Swamp Milkweed yesterday tells me that my Red Cedars have been playing host to green caterpillars that have likely been helping to feed the three broods of Eastern Bluebirds reared by the ambitious parents that nested on my property this year.
In a world so filled with darkness these days, the appearance of this petite green butterfly gives me at least small hope for my planet’s future.