Black cherry finger gall, larval food source for C. serotina, Cherry Gall Azure.
And to round out our collection of ID tips for spring azures in the mid-Atlantic, here’s a copy of Harry Pavulaan’s and David Wright’s description of a new azure species, Celastrina serotina, or Cherry Gall Azure. C. serotina is also a univoltine species with the interesting food plant association of feeding primarily on galls formed by eriophyid mites on black cherry (Prunus serotina) leaves, the so-called Black Cherry Finger Gall. According to the 2005 paper, though, serotina also feeds on incipient flowers of a number of other plant families, as many other Celastrina do.
Harry and David describe serotina this way in their paper:
“Male: Dorsal color uniform light blue; some individuals with purplish-blue tint. White insuffusion between veins on DHW common. Androconia present. Wing fringes white; black checkering minimal to absent. Ventral color uniform white to light gray-white. Black maculations reduced. Most individuals are lightly marked, similar to form “violacea”, except in RI, MA, and PA where a few (1%, 3%, 9% respectively) have partially fused maculations on the VHW disc (form “lucia”). FW length 10.2-15.0 mm (mean 13.5, n = 52). Rhode Island and southern New England males average slightly larger than those from northern New England, Canada, and higher elevations in southern range (WV, MD, PA).
Female: Dorsal color lustrous metallic light blue; some individuals with purplish tint. Black on DFW costa and outer margin. DHW with series of submarginal black dots. White insuffusion on DHW common; occasionally also on DFW. Wing fringes white; black checkering minimal to absent. Ventral color and pattern as in male. Forewing length 10.5-15.0 mm (mean 13.4, n=28). Rhode Island and southern New England females average slightly larger than those throughout rest of range. Note: The male genitalia of eastern North American Celastrina species differ from Eurasian C. argiolus L., but they cannot be reliably distinguished from one another. The sclerotized apical process of the valve bears small teeth, which tend to be largest in neglectamajor and smallest in neglecta. All remaining taxa, including serotina, are intermediate in this character. No distinguishing features of female genitalia of eastern North America are known.
Although Cherry Gall Azure was already in use as a common name to describe the azure that had been observed feeding on cherry galls, Pavulaan and Wright proposed the common name “Late Spring Azure” but that never took off, apparently.
Given the decade since the serotina paper was published, maybe Harry will favor us with simpler identification tips! In our area, C. serotina seems to be resident in the far western counties of Maryland.
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