Miami Blue - Synopsis of Proposed Listing

[Mike Quinn]

Answers to most of the questions I've seen posted are covered in the Federal
Register. Here's a synopsis of some of the more interesting aspects of the
proposed listing of the Miami Blue. Comments in brackets [ ] were added.
Mike 

-=-=-=-=-=-=-=-=-=-=-=-=-=-
Mike Quinn
Invertebrate Biologist
Wildlife Diversity Branch
Texas Parks & Wildlife
mike.quinn at tpwd.state.tx.us

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Federal Register / Vol. 67, No. 2 / Thursday, January 3, 2002 / Proposed
Rules

SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a 90-day
finding for a petition to list the Miami blue butterfly (Hemiargus thomasi
bethunebakeri) under the Endangered Species Act of 1973, as amended.

On June 15, 2000, we received a petition, dated June 13, 2000, from Dr.
Jeffrey Glassberg, president of the North American Butterfly Association,
Morristown, New Jersey, and Mr. Mark Salvato, an entomologist in St.
Petersburg, Florida. The petition requested that we list the Miami blue
butterfly as an endangered species on an emergency basis, and that critical
habitat be designated concurrent with listing.

Minno and Emmel (1993) [Butterflies of the Florida Keys] stated that
''although populations of the Miami blue have declined on the southern
mainland, it is still locally common in the Keys'' (pp. 134- 35). However,
this statement was based on a 1980 reference.

The petitioners' evidence, augmented by other available information,
especially a paper by Calhoun et al. (in press), demonstrate that this
subspecies has become hard to find. No observations of the Miami blue were
supported by photographs or specimens from 1993 (Calhoun et al. in press)
until November 1999, when Jane Ruffin provided a photographically verified
report of about 50 individuals at a site in southern Florida. Her report was
published in the spring 2000 issue of American Butterflies (Ruffin and
Glassberg 2000). Calhoun et al. (in press) note an additional confirmed
population near the one observed in 1999 as well as a credible sighting by
R. Gillmore on Key Largo, which was posted on the North American Butterfly
Association's website
(http://www.naba.org/sightings/sightingsMay2001Archive.htm).

[May 5, 2001, Schaus' Swallowtail, Miami Blue, Caryfort Circle on North Key
Largo, FL (R Gillmore)]

The petitioners cited biologists and others who have searched for
butterflies in southern Florida in recent years without sighting the Miami
blue. This strongly indicates that the Miami blue is now very restricted in
its distribution and nowhere abundant.

Larval food plants for the Miami blue butterfly include the seed pods of
nickerbeans (Caesalpinia spp.), which are common tropical coastal shrubs and
vines, as well as blackbeards (Pithecellobium spp.) and perhaps other
members of the pea family, such as Acacia (Calhoun et al. in press). Miami
blue larvae also utilize balloon vine (Cardiospermum halicababum) [sic]
seedpods (Opler and Krizek 1984, Minno and Emmel 1994). These vines,
belonging to the soapberry family, are not native to Florida, but are
relatively common, especially in urban areas. Additionally, Calhoun et al.
(in press) suggest that larvae of the Miami blue, like those of the
nickerbean blue [Hemiargus ammon], may feed on species of Acacia that are
abundant on Big Pine Key.

The petitioners stated that, due to aspects of the Miami blue's natural
history, especially its association with ants, ''roadside [mosquito control]
adulticide applications may be having much larger negative impacts on H. t.
bethunebakeri populations than on those of other lycaenid species in the
Keys. Miami blue larvae mature in the stem and seed pods of their host.
These larvae leave the entrance holes open so that ants can enter the seed
pods and stems and interact with the larvae. Dr. Jenella Loge (University of
Utah) has discovered that these ants and the Miami blue larvae die when
spraying begins in late spring on the Keys. Larvae of other lycaenid species
on the Keys, ones without mutualistic relationships with ants, plug the
holes of their seed pods and stems to keep would-be predators outside, and
this may also restrict the entrance of adulticide spray.'' About half of the
world's lycaenid butterfly species associate with ants. Cushman and Murphy
(1993) suggest that ant-dependent lycaenid butterflies are inherently more
vulnerable to extinction than those that are not ant-dependent because of
the consequences of needing both the right food plants and the right ants,
simultaneously. Based on information from Calhoun et al. (in press) and
Salvato (1999), mosquito spraying appears likely to have contributed to the
decline of the Miami blue and might be inhibiting recolonization of suitable
habitats.

We have reviewed the petition, the literature cited in the petition, and
other literature and information available in our files. On the basis of the
best scientific and commercial information, we find the petition presents
substantial information that listing this species may be warranted.

If you wish to comment, you may submit your comments and materials
concerning this finding to the Supervisor, South Florida Ecological Services
Office, U.S. Fish and Wildlife Service, 1339 20th Street, Vero Beach,
Florida 32960.

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Complete Document:
http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=2002_register&doci
d=02-36-filed.pdf


 
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