A guide to
identifying the Azure (Celastrina) species
to the Connecticut Butterfly Atlas, four species of azures are found in
Connecticut, the Spring Azure (C. ladon), the Summer Azure (C.
neglecta), the Cherry Gall Azure (C. serotina) and the Appalachian
Azure (C. neglectamajor).
of these species, the Appalachian Azure, is restricted to the western
edge of the state along the New York state border and is closely
associated with it larval food plant, Black Cohosh (Cimicifuga
racemosa). As a result, observers looking at butterflies CT will
rarely, if ever, see Appalachian Azures. However, the other azure
species are widely distributed across the state and distinguishing the
various azure species can be a challenge, particularly in the spring
when three species of azures are on the wing and there is some overlap
in the flight times of these species.
I wrote this article to assist observers in identifying the three
species of azures that are commonly found in the state. It is
important to note that there are significant limitations to this guide
because it is only useful for identifying males and it assumes the
observer can see the upper side of the butterfly.
only included males, because it can be very challenging to identify
females, even in those situations where the observer is able to net the
insect and observe it in hand. Female azures can be distinguished
from males by the broad black band on the outer edge of the
forewing. Males lack that broad black band. To be able to
identify male azures, it is important to see the upper side of the
insect since that is where you will find the field marks that are most
useful for distinguishing the various species. Unfortunately,
since azures usually hold there wings closed when they land, seeing the
upper side can be a challenge unless you can net the insect.
connection this project, I reviewed the identifications of the azure
specimens collected during the CT Butterfly Atlas. This enabled
me to document the flight times for the azure species that occur in the
state in the spring. Information on flight times is included in
the species accounts.
following abbreviations are used in this article:
Peabody Museum, New Haven, CT
Azure Celastrina ladon (Cramer)
Fig. 1, 2,
side- The wings are purplish blue. Under magnification, the
scales are very close set and overlap each other, particularly on the
FW. The scales on the forewing are often very haphazardly
arranged, although that is not easy to see in Fig. 7.
side- The ground color is grayish brown. Usually, the HW has a
brown border and is often heavily spotted or blotched. See
Fig. 2. However, there is at least one aberrant specimen
collected during the Atlas project that is a uniform light brown
without dark spots or splotches.
time- One brood; March 29 to May 31.
The Spring Azure can be distinguished from the other azure species by
the combination of the grayish brown ground color on the underside of
the HW and the purplish-blue color and the close set overlapping scales
on the upper side of the FW. Cherry Gall Azure and Summer Azure
have a lighter ground color below and lack the overlapping scales on
the upper side of the FW. The upper side of the HW of Summer
Azure is much whiter than the upper side of of the HW of Spring
Azure. While the dark markings on the underside of Cherry Gall
Azure can be quite similar to the dark markings on the underside of
Spring Azure, on the Cherry Gall Azure, the rows of blue scales on the
upper side of the FW are separated by distinct white lines.
Azure is the first species of azure to emerge in the
Azure Celastrina neglecta (W. H. Edwards)
Fig. 3, 4,
side- The FW is purplish blue; the HW is much whiter than the FW.
On the HW, the extensive white scales are arranged in distinct rays
that reach the back edge of the HW, while the veins are blue.
This is very evident in Fig. 3. Under magnification, the rows of
scales on the FW are very close set but do not overlap each
The ground color is a light gray with variable pale markings.
time- Multiple broods; May 15 to September 5.
Summer Azure can be distinguished from the Cherry Gall Azure by the
white markings on the upper side of HW. On Cherry Gall Azure, the
white scales are arranged in a uniform light patch in the center of the
HW and a blue margin is evident along the back edge of the HW. This is
contrast to Summer Azure where the white patch extends to the edge of
the HW and the blue is restricted to the veins. In addition, the
rows of white scales on the upper side of a Summer Azure FW are much
closer set than they are on Cherry Gall Azure. Summer Azure can
be distinguished from the Spring Azure by the whitish HW above and the
lighter ground color and much reduced markings on the underside.
Azure is the last species of azure to emerge in the spring and is the
only species of azure flying during the summer.
Azure Celastrina serotina Pavulaan & Wright
side- Wings above light purplish blue with a whitish patch in the
center of the HW and a blue band along the back edge of the HW.
Under magnification, the rows of blue scales on the upper side of the
FW are separated into rows that are separated by white lines. See
side- The ground color is a light gray with variable dark markings.
While many specimens are often quite pale underneath, see, for example
Fig. 6, on some specimens, a brown marginal band is present on the back
edge of the HW or a dark patch can present in the center of the
time- One brood; April 25 to June 16.
Cherry Gall Azure can be distinguished from the Summer Azure by the
white markings on the upper side of HW. See the species account
for Summer Azure. Examples of Cherry Gall Azure with extensive
brown markings on the underside of the HW can be confused with Spring
Azure. To distinguish individuals with extensive brown markings
on the underside, you need to look at the scales on the upper side of
the FW under magnification. Compare Fig. 7 and Fig. 9.
Gall Azures emerge after Spring Azures but before Summer Azures and
often stay in close proximity to their larval food plant, Black Cherry
want to thank Harry Pavulaan for providing me with information on how
to distinguish the various azure species that occur in the state.
Without the information provided by Harry, it would not have been
possible to write this article. I also want to thank Larry Gall
at the Yale Peabody Museum who made the CT Butterfly Atlas voucher
specimens and the Museum collection available for study. Larry
Gall also photographed the specimens and assembled the plates.
J. E., Gall, L. F., Wagner, D. L. [ed.] 2007. The Connecticut Butterfly
Atlas. State Geological and Natural History of Connecticut Bulletin No.
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7. Spring Azure Celastrina ladon (Cramer). West Rock Ridge St. Park,
New Haven, L. Gall coll., April 19, 1980 (YPM ENT 732273); 3-4, 8.
Summer Azure Celastrina neglecta (W. H. Edwards). Mansfield, H. Wilhelm
coll., July 11, 1959 (YPM ENT 732274); 5-6, 9. Cherry Gall Azure
Celastrina serotina Pavulaan & Wright. Beckley Bog, Norfolk, S.
Hessel coll., May 31, 1958 (YPM ENT 732285).
Connecticut Butterfly Association
P.O. Box 9004
New Haven, CT 06532-0004