One day in the next few weeks, you may be walking through a field on a sunny day. You may see a tiny blue butterfly, with wings the size of thumbnails, flitting over the meadowsweet. If you know your butterflies, you might say to yourself, "Ah, there's a summer azure." And according to all the butterfly field guides, you would be right.
But are the field guides right? Could you actually be looking at a butterfly species unknown to science? Even the leading butterfly experts don't know for sure.
For years, nobody took a close look at azures, perhaps because they are so common throughout the northeastern United States. Even just a few decades ago, the Northeast was thought to have just one species of azure butterfly. Sure, it was a species that didn't seem to follow the same rules as other butterfly species – more on this in a moment – but the classification seemed to get the job done.
"The first descriptions of azures in this country were just a mess," says butterfly expert Harry Pavulaan.
Pavulaan is a cartographer who lives and works in the Washington, D.C., area. He has been pursuing butterflies as a hobby since he was a child, and his interests have grown in sophistication through the years. Butterflies for him are "a passion-driven avocation."
Pavulaan was trying to put together a comprehensive list of the butterflies of Rhode Island (where he was living at the time), when he noticed, as a cartographer might, that azure butterflies varied between different locations in a way that suggested they belonged to different species rather than being different forms of the same species.
Correspondence with a fellow butterfly enthusiast in Pennsylvania, a medical doctor named David Wright, reinforced the belief of both that there were more species of azures in the Northeast than just the two that were by then widely accepted: a spring azure and a summer azure.
So the two men set to work trying to figure out what some of those species might be.
Pavulaan says the key factors in teasing out butterfly species, particularly among the azures, include the flight period, which is the time during which the adults of the species are flying around looking for love so they can continue the species.
Another clue is the host plants. Many butterflies have a single plant that they rely on for at least one stage of their life cycle. Often it is the only plant the caterpillar can eat, so the adult butterfly will do its best to lay its eggs only on that plant. Sometimes a butterfly species will rely on any of several plant species, or an entire family of plants, and sometimes, but not often, just about any plant will do.
In Vermont, when Kent McFarland, director of the Vermont Butterfly Survey, tried to sort out the hundreds of azure butterfly records – photos, descriptions and specimens – sent in by survey volunteers, he turned to Pavulaan and Wright for help.
Pavulaan and Wright pored over the Vermont azure specimens and compared them with their own records, observations and theories. They suggest that there are three species of azure butterflies in Vermont, although they say there may be as many as five.
The big three begin with the northern azure, a Canadian species whose range dips down into Vermont and whose flight time is in early spring. Then there is the cherry gall azure, which flies in mid-May. Finally, there is the summer azure, whose flight in Vermont, according to the volunteers of the Vermont Butterfly Survey, hits one peak in early July and another in early August.
The double peak hints to Pavulaan that another species is lurking within this species designation. "The one that flies in late June into early July, we're not sure what it is. It may be undescribed." That is, it may be a species new to science that has not been described in the scientific literature.
If these are two species, you can't really tell them apart by looking at them. Pavulaan would like more information on the host plants used by the two flights of summer azures in Vermont. McFarland would like some DNA samples. Both agree that it will take several years and more funding to get a clear answer on whether there are two species of azures that fly in Vermont in the summer. Where that time and money will come from, they have no idea.
But we humans are inquisitive; we strive not only to survive in our environment but to understand it. These two experts believe that someday the mystery will be solved. It just may not be someday soon.
Madeline Bodin is a writer living in Andover. The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine and is sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation: firstname.lastname@example.org.MORE IN Movies
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