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Blackburns
Sphinx Moth
/ Manduca blackburni
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Blackburns
Sphinx Moth is Hawai`is largest native insect, with a wing
span of up to 5 inches (12 centimeters).
Like other sphinx moths, it has long, narrow forewings and a thick,
spindle shaped body tapered at both ends. It is grayish brown in
color with black bands across the top margins of the hindwings and
five orange spots along each side of the abdomen. |
The large caterpillars
occur in two color morphs, bright green or gray with scattered white speckles
throughout the back and a horizontal white stripe on the side margin of
each segment.
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| Moth
photos courtesy of Betsy Gagne |
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Habitat
& Behavior:
Historical records of this species are mostly from coastal,
lowland, and dryland forests in areas receiving less than 50 inches (120
centimeters) of rainfall, though they have been collected from sea level
to 2,500 feet (760 meters). It was most common historically on Maui. Larvae
of Blackburns Sphinx Moth feed on native `aiea trees (consuming
leaves, stems, flowers, and buds) and other plants in the nightshade family.
However, many of the host plants recorded for the species are not native
to the Hawaiian Islands, and include tree tobacco, commercial tobacco,
and tomato plants.
Development from egg to adult can take as little as 56 days, but pupae
may aestivate (dormancy during a period when conditions are hot and dry)
in the soil for as long as a year. Adult moths can be found year round
but seem to be most active during two periods, January to April and September
to November. Adult moths are strong fliers.
Past &
Present:
Once found on six Hawaiian islands, the moth now exists
only on Maui, Kaho`olawe, and the island of Hawai`i. They were believed
extinct until 1984 when a small population was rediscovered in a lowland
dry forest on the south coast of East Maui (Kanaio area).
Additional small isolated populations are now known from other parts of
Maui. Populations were recently discovered on Kaho`olawe (the first record
of this species on this island) in 1997 and in 1998 in North Kona on the
island of Hawai`i.
Threats to Blackburns Sphinx Moth include introduced ants and parasitic
wasps that prey on the eggs and caterpillars, and the loss of its native
host plant, `aiea, which is a dryland forest tree.
The native host
plant is found in endangered ecosystems, dry and mesic forests, and has
been adversely affected by feral animals, alien plant invasions, and habitat
conversions associated with development. Ants are not a natural component
of Hawai`is arthropod fauna and they are particularly destructive
due to their high densities, aggressiveness, and broad range of diet.
A high percentage of the eggs of the sphinx moth are destroyed by alien
parasitoid wasps and ants. In addition, the moth is also susceptible to
overcollection by individuals for their personal collections or for trade.
Because the remaining populations are small and restricted, the potential
for extinction from a chance event, such a fire or a hurricane, is greatly
increased.
Conservation
Efforts:
This native Hawaiian moth is the first Hawaiian insect to be added to
the endangered species list by the U.S. Fish and Wildlife Service (Service).
The Service is currently funding research examining the life history,
captive rearing, and conservation biology of the sphinx moth. Additionally,
the Service is currently a partner in a dry forest restoration project
on State lands in the same area that the North Kona population of the
moth occurs.
The Kanaha Pond Sanctuary dune restoration project is currently being
modified to include planting of the native host plant since sphinx moth
larvae were recently observed on plants in the sand dune area in the Sanctuary.
The military uses part of the general area where the East Maui population
occurs for training and has adopted measures to prevent fires, alien seed
dispersal, and vegetation damage as a result of training. While no conservation
efforts specifically for the moth are currently underway on Kaho`olawe,
the State, the Kaho`olawe Island Reserve Commission, and the U.S. Navy
are aware of the presence of this species and have sponsored surveys to
identify the distribution of the moth on the accessible parts of the island.
Trivia
quiz:
What threatens the continued existence of Blackburns Sphinx Moth
?
[a] birds
and bugs
[b] alien parasitoids and ants
[c] snakes
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