Celastrina idella photo by Dave Amadio, Salem WMA April 4, 2011
Yes, our second “spring azure” species is now on-the-wing. Holly azures make a tricky ID, but their emergence means checking out those little blue butterflies at our feet has suddenly become a lot more fun!
We had an unusually early record for holly azure on 3/19/11 (Lizard Tail Swamp, W. Kerling), but early to mid-April is when we can generally expect first emergences, especially north of Cape May County. Dave Amadio’s find of a holly on April 4th in Salem County probably announces the start of their primary flight period.
Separating idella (holly) from lucia (blueberry azure) by sight involves factoring in several variables. And it also seems we also have to keep in mind that not all free-flying individuals can be certainly named.
One key seems to be the “cleaner” and brighter underside on idella vs. lucia. The dark spots are smaller and seem to stand out more sharply from the ground color of the underwing.
The majority of C. lucia individuals (74%) are the “marginata” form with a dusky ground color below and dark markings, especially on the trailing edges (the margins) of the wings. Almost all other lucia individuals (24%) are “lucia” form — which differ mostly from “marginata” by also showing the “lucia” patch in/near the center of hind wing. Only a few C. lucia are in the lightest-marked “violacea” form (about 2%, 1 in 50). By contrast, the majority of holly azures, C. idella, (90+%, if I understand the literature) are light below; <6% show the “lucia” patch — and Wright & Pavulaan note those few dark “idella” might be hybrids of the two sibling species.
C. lucia also emerges earlier (generally 2+ weeks) than C. idella, so wear can be a tip, at least from mid-April on.
Wright & Pavulaan note that the colors are slightly different: males of C. lucia are “violet-blue,” while males of C. idella are “uniform light-blue; some individuals w/distinct purple tint.” C. idella individuals also are “distinctly smaller,” W&P note. Both color and sizes can be hard to evaluate on living butterflies, however — at least for me.
The most certain separation for those of us not collecting specimens is the host plant. C. lucia does not use holly; C. idella does. Anyone out there with a good photo of idella ovipositing on its host? That would be wonderful to post here on our blog.
See the post below “Azures & Others” (3/17/11) for photos of all three forms of C. lucia and a link to Wright & Pavulaan’s original description of C. idella.
I am ignoring here the third newly-split species in our area, Edward’s azure, C. ladon, because it seems either rare or non-existent through most of NJ’s southern eight counties. Wright & Pavulaan’s maps indicate it is most likely to be found in Salem or Gloucester, away from Pine Barrens soils, where dogwood is common. If any readers would like to offer some tips on separating ladon from idella, I’d be very pleased to post them here on this blog.
I am also ignoring a fourth apparently-even-rarer possibility: the spring brood of summer azure, C. neglecta, for which we have at least one recent record in our area — photo’d by Mike Crewe at Cape May Point on March 31 last year, and identified by Dale Schweitzer.
Some words of wisdom from different sources about this complex complex:
Paul Opler & G.O. Krizek, Butterflies East Of The Great Plains (1984) “In recent years, it has been realized that several sibling species are involved [under the name spring azure]. Seasonal and geographic variation confuses matters.”
J.P. Brock & K. Kaufman, Butterflies Of North America (2003), “It now appears certain that there are several species, all very similar. Their classification is still being studied. Unless you are a specialist on this group or have access to detailed information for your local area, it may just be best to enjoy them as azures — and marvel at the fact that butterflies can still keep so many secrets from us.”
Rich Cech & Guy Tudor, Butterflies Of The East Coast (2005), “We may be, simply enough, witnessing the fragmentation of an ancestral species.”
David Wright in an email to our club (2009), “Study what’s at hand and take lots of photos. Eventually, it begins to make sense.”
Let’s close with two more photos from Dave Amadio of his idella holly from this week (nectaring on Cardamine hirsuta, a mustard):
Celastrina idella photo #2 Dave Amadio, Salem WMA April 4, 2011
Celastrina idella photo #3 Dave Amadio, Salem WMA April 4, 2011