1. (left) Ceraunus Blue. Oct. 10, 1995. Roma, Starr Co. Texas
2. (right) Ceraunus Blue. Aug. 23, 1991. Gainesville, Alachua Co. FL
3. (left) Miami Blue. Dec. 10, 1981. Grassy Key, Monroe Co. Florida
4. (right) Reakirt's Blue. June 8, 1995. Pontotoc Ridge Preserve, Pontotoc Co. Oklahoma
5. (left) Marine Blue, male above. Sept. 23, 1993. Catalina Island, California (photo by Harry Darrow)
6. (right) Marine Blue. Aug. 2, 1996. Garden Canyon, Cochise Co.Arizona
In North America north of Mexico, there are 5 species of blues in the two genera Leptotes and Hemiargus. Collectively, I refer to these species as black-eyed blues, because one of their more conspicuous features is the presence of one or two prominent black eye-spots, with some iridescent blue, near the outer angle of the HW below (see photo 1). The only other blues with this feature are the tailed-blues, and they have tails and lack the iridescent blue (other blues, such as pygmy-blues, have black eye-spots, but they have a whole series, not just 1 or 2).
Once you have determined that a blue is a black-eyed blue, look at the leading edge of the HW. If there are two prominent black spots here, then the blue is in the genus Hemiargus, and is either a Ceraunus, Reakirt's, or Miami blue. If there are no black spots, then the blue is a Leptotes blue, either a Marine or Cassius blue.
7. (left) Cassius Blue. Feb. 3, 1996. Key Largo, Monroe Co. Florida
8.(right) Ceraunus Blue male. Sept. 24, 1994. Gainesville, Florida
Let's start with the Hemiargus blues. First take note of your location. Miami Blues are only found in extreme southern Florida (and in the West Indies) while Reakirt's Blues are normally found west of the Mississippi River. Ceraunus Blues reside in extreme southern U.S. Florida, south Texas and southern California but occasionally move northward.
Ceraunus Blues could be confused with
either Reakirt's or Miami blues. In Florida and
southern California, local populations of Ceraunus
Blues have one black eye-spot (see photo 2), while
the population in southern Texas has two black eye-spots (see photo 1). The stronghold of
Reakirt's Blue is the Southwest, but its range
expands northward each year, occasionally reaching northern California, southern Canada and
western Ohio. Where Ceraunus Blues and Reakirt's
Blues overlap, Reakirt's may easily be distinguished
by the very bold, black postmedian spots on the FW (see photo 4). Ceraunus Blues do have
post-median spots on the FW, but these spots are
On the Florida keys, Miami Blues may be distinguished from Ceraunus Blues by their wide white postmedian band, present on both the HW and FW (see photo 3), and by the presence of a second black eye-spot below the first one. In addition, female Miami Blues have an orange spot at the outer angle of the HW above that Ceraunus Blue females lack (Ceraunus Blue females look very much like the Reakirt's Blue female shown in photo 9).
9. Reakirt's Blue female. March 19, 1997. La Joya, Starr Co. Texas
To distinguish Cassius and Marine blues, location is again helpful. Cassius Blues are most common in Florida where Marine Blues do not occur. Both species are found in southern Texas and here, most individuals can be identified by the fact that Cassius Blues tend to be much whiter than are Marine Blues. But, some individuals almost overlap in pattern. With these, if possible, look at the portion of the FW indicated in photos 6 and 7. Marine Blues have a continuation of a stripe in this area while Cassius Blues are white.
Above, male Marine Blues have a
characteristic ultramarine blue at the wing bases and a
violet sheen on the rest of the wings (see photo 5).
The range of Marine Blues is similar to that of
Reakirt's Blues, with similar irruptive movements.
All photographs this article by Jeffrey Glassberg, except as indicated.
by Thomas C. Emmel. 1997. Friedman/Fairfax (15 W. 26th St., NY, NY 10010). ISBN 1-56799-525-X. 112 pp. 106 color phtotographs. $19.95
Common Butterflies of the Southwest
by Richard Bailowitz and Douglas Danforth. 1997. Southwest Parks and Monuments Assn. Tucson (221 North Court, Tucson, AZ 85701). ISBN 1-877856-84. 64 pp. booklet. 78 color photographs. $6.95
Common Butterflies of California
Eastern Forest Caterpillars