Harry Pavulaan, one of our local azure experts who kindly provided many of the the comments that I post here each spring to help sort out the complicated ID picture for spring-flying azures, recently corresponded about some new data he’s been studying that helps distinguish Northern Azure, Spring Azure and spring-form Summer Azure. Because these species are difficult to tell apart (and even with this new information I often find them hard to distinguish in the field, let alone from photos), and because at least in some populations he’s studying the three all fly together at the same time in their spring flight, azure ID in our area in the spring has gotten even more challenging!
Harry notes that these three all are found near Gore, VA, in Frederick Co.; in addition he’s found lucia “at several other sites in northern Virginia, mainly at George Thompson WMA (Lake Thompson area, NOT the ridge top) where it is quite rare, around Big Meadows off Skyline Drive, and the ridge north of Reddish Knob on the W.V. border.
Lucia occurs on Appalachian ridges in this region and is closely associated with Wild Black Cherry, but ladon and spring neglecta also use that plant. In Maryland, lucia has been found on Town Hill and it must occur elsewhere in Green Ridge State Forest. I’ve only found ladon there in spring (not even spring neglecta!). It must be associated with Black Cherry in that area. Lucia is very common on top of ridges in the South Mountain State Forest west of Gettysburg, PA where is feeds on lowbush blueberries. Not far from Maryland and I’ve always held up hope of finding it around Camp David, but to no avail. They should be very common up at Cranesville [Swamp, Garrett Co. -- REB] and fly with an odd high-altitude population of neglecta in similar habitats in W.V.”
Here are some miscellaneous notes about the azures he’s been studying in N. VA excerpted from Harry’s email:
>>Celastrina ladon. Males are typically of the typical spotted (ventral hindwing) phenotype, showing no tendency to develop darkened ventral hindwing margins or dark ventral hindwing discal patches, which are more frequent toward the northern portions of the species’ range. Under magnification, males of C. ladon are easily distinguished from all other blue Celastrina species by their unique male wing scale structure; ladon is the only blue Azure in which the males lack androconia. All other blue Azure species have male androconia (the dark brown C. nigra is the only other Azure that lacks androconia) Adults of ladon tend to be slightly paler and more violet-blue in color than either lucia or neglect. Moreover, .Work that Harry and his colleague David Wright have found C. ladon to be univoltine throughout its range.
Celastrina lucia. Males are generally of the spotted (ventral hindwing) phenotype, with some individuals displaying darkened ventral hindwing margins [described as form marginata (W. H. Edwards, 1883)]. Males of C. lucia are easily distinguished from males of C. ladon which bear the unique wing scale structure. Adults of lucia tend to be noticeably more metallic, deeper blue in color than ladon when they are fresh, but have a peculiar tendency to become more violet when flight-worn with age. Males of lucia can be distinguished from sympatric males of spring form neglecta by the lack of very distinct white wing veins along the leading forward edge of the dorsal side of the forewing, which are characteristic of spring form neglecta. Also, individuals of spring form neglecta bear clear wing fringes, while in lucia, they are either darkened or checkered black and white. Females are generally difficult to distinguish, as both lucia and neglecta females tend to be very similar in appearance, both being noticeably lighter blue than females of ladon. In series, lucia females from the Appalachian region tend to be markedly smaller than neglecta females and have narrower black outer margins on the dorsal forewing. C. lucia is known to be an obligate univotine butterfly throughout its range.
Celastrina neglecta spring form. Males are typically of the distinctly-spotted ventral hindwing phenotype, showing no tendency to darkened ventral hindwing margins or dark ventral hindwing discal patches. Males of C. neglecta spring form are easily distinguished from males of C. ladon which bear the unique wing scale structure, however, in all other respects, they are extremely similar to ladon and very difficult, if not impossible, to distinguish by ventral markings alone. Adults of neglecta spring form tend to be bluer in color than ladon, but are very similar in color to lucia. Males of neglecta spring form can often be distinguished from sympatric males of lucia by the presence of distinct white wing veins along the leading edge of the dorsal forewing, which is characteristic of neglecta spring form; but not always reliable, as in some individuals the wing veins might be subdued. Also, neglecta spring form bears clear wing fringes on the hindwing edge, while in lucia, they tend to be darkened or checkered; and in ladon they tend to be darkened but can appear light in some individuals. Females are generally difficult to distinguish from lucia, but are generally larger and have broader black outer margins on the dorsal forewing.
Celastrina neglecta summer form. The summer form of neglecta is uniquely different from the three spring phenotypes, in that the venter is very white, and dark markings are reduced to mere dashes and dots. On the dorsum, the males and females both display characteristic distribution of white coloration on the hindwings, arranged in rays between the wing veins. This phenotype has been produced in reared offspring of spring form females throughout the range of neglecta. <<
Harry also gives this tip to bolster my field ID skills : “With practice, and with a series of specimens of the different species, one can easily see the reflective effect of the unique ladon male scales. Ladon males have a greasy sheen. All other blue Celastrina do not have this greasy sheen (brown nigra has the unique male scale structure). Best way to see this is to hold a tray of a few specimens that you know are ladon and a few that you know are not (i.e. summer neglecta, neglectamajor) for practice. Move them around in direct sunlight at different angles and eventually the unique ladon reflectance will suddenly reveal itself to you. Once you see it, identifying male ladon specimens is a snap.” [FYI -- There's a good electron microscope image of the androconia in Wright & Pavulaan's description of C. idella.]
I think a future where any azure identification is a snap for me might be a ways off, but I’ll be practicing this spring!