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The Pipevine Swallowtail (PvS) is one of several
very dark (nearly black) swallowtail butterflies. Some people remark that at a
distance it looks like a plain black butterfly with no other distinguishing
marks apparent. Up close, the upper side of the hind wing appears iridescent
blue or blue green with a row of whitish spots. In the female this row of
whitish spots extends onto the fore wing. The under side of the hind wings
have the orange markings typical of most other swallowtail butterflies.
As enthusiasts gain experience studying butterflies they come to realize the
critical role that the host plant plays in the life cycle of butterflies. The
host plant for PvS (Aristolochia) seems to be cloaked in mystery and can
create considerable discussion as evidenced by the postings on the
carolinaleps list server last Fall. For this reason I felt that PvS's might
be a timely topic for a column based on the experiences of others since I
cannot yet claim any personal experience raising Pipevine Swallowtails.
Two species of Aristolochia are considered native to North Carolina. A.
serpentaria (Virginia Snakeroot) is a ground hugging vine that is scattered
throughout the state and is probably the only native Aristolochia in the
piedmont area. Its usual habitat is mixed deciduous forests, woodland margins
and stream banks. It may be overlooked since usually only the leaves and part
of the stems show above the leaf litter. A. macrophylla (Dutchman's Pipe) is
native to the mountains, and should be found in rich woods, coves and stream
banks. This is a climbing vine that is often trained up trellises in garden
plantings and mature plants can develop woody stems. A. macrophylla has been
referred to as A. durior but A. macrophylla is considered the correct name.
A. tomentosa is native to the southern states and probably occurs in South
Carolina (and possibly North Carolina) Other species are native to
California, Texas and New Mexico respectively while several tropical species
have been introduced into Florida.
The orange eggs are generally deposited on the stems or the underside of the
leaves of the host plant. They may be deposited singly but more often in
clusters of 4 or 5 and sometimes up to 20 eggs per cluster. The young
caterpillars feed together (termed gregarious behavior) and then at some
point each heads off alone to seek its fortune. Some observers say they split
up after the first instar while others say they stay together through the
second or third instar. Paul Calvalconte reported that the caterpillars are
inclined to drop to the ground when disturbed. They usually hang on in the
wind but drop to the ground from most other disturbances. This large
concentration of hungry caterpillars on one plant is what usually attracts
attention (and then concern). This is often the case in gardens where there
may be only one or two plants or the plants have not yet had time to develop
significant size. Before long the plant has been stripped of all leaves and
there is no other acceptable food in sight. The vines are fairly robust and
will re-grow new leaves, but generally not fast enough to satisfy the waiting
caterpillars. While both A. serpentaria and A. macrophylla seem to be equally
desirable ovipositing sites, the A. macrophylla ("large leaves")
will generally provide more forage for the caterpillars. The last instar
caterpillars are described as black or sometimes a purplish dark chocolate
with rows of fleshy tubercles with red bases along the body. The pair at the
head are longer and probably are used as feelers.
There has been some debate about the suitability of A. elegans (Calico
Flower) as a host plant for PvS. The conclusion seems to be that while the
female PvS will oviposit on A. elegans the caterpillars do not thrive and
quite often die. This past summer Jim Nottke had an interesting observation
while trying to raise some " foster" PvS caterpillars that had
eaten themselves out of their original home at Patrick Coin's. Jim's supply
of A. serpentaria was soon consumed so he was forced to try some
alternatives. The caterpillars indeed refused A. elegans but would nibble on
a hybrid A. elegans x A. macrophylla and grew slowly. However, as the A.
serpentaria regenerated those leaves were definitely favored and quickly
consumed.
Two and possibly three broods are considered normal for North Carolina.
Patrick Coin has noticed a two year cycle in PvS numbers. In alternating
years there are enough caterpillars to completely defoliate the A.
serpentaria in his yard and neighborhood. (2000 was such a year so this year
may be a year of lower numbers.) The chrysalises may be a green or brown
color. Like other swallowtails they are held erect with a silken sling or
girdle although they have a rougher appearance with more projections and
bumps. Chrysalises from earlier broods have been found attached to the host
vine but more often the caterpillars move off to another location to pupate.
Sparrel Wood has found PvS chrysalises over sixty feet away from the presumed
host plant. The chrysalis is the over wintering form for PvS's and Don and
Sheryl Dorton of Charlotte had captive raised PvS butterflies emerge in early
April. A photo of the caterpillar and the chrysalis can be seen in Florida
Butterfly Gardening by Marc C. Minno and Maria Minno. However, I suspect the
photo of the chrysalis was inverted by the publisher.
I would like to thank those credited above plus
Will Cook, Elizabeth Hunter, Tom Krakauer, and Smitty Mallard who all shared
information that was used in the creation of this column.
I await your contributions or suggestions for
the next Larva Lore column.
Charles Cameron, 336-852-9211,
ccamer@triad.rr.com
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Pipevine
Swallowtail found on Carolina Columbine in Orange County, NC on April
18,1999.
Pipevine
Swallowtail Caterpillar 4th or 5th instar.
The two
photos below are male and female Pipevine Swallowtails both found along the
Blue Ridge Parkway in Bedford County, VA on July 16, 2000.
Male
above
Female
above
Photos
courtesy of Randy Emmitt
birdcr@concentric.net
All rights reserved
Lavra Lore #2
Variegated Fritillaries (Eupoieta claudia)
December 2000
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