Photographer:Lesley Ingram Source: www.bugwood.org Copyright: CC BY 3.0
Adult Description: Adult Torpedo Bugs (Siphanta acuta) are bright green in color with veins along their dorsal side mimicking a leaf. Their eyes are pink and the head comes to a point, giving this insect a torpedo shape and aerodynamic structure. The wingspan of the adult torpedo bug is about 25mm. Once in the adult stage, life expectancy of S.acuta is only around 2 months.
Larva Description: The name torpedo bug is believed to be derived from the nymphs’ ability to jump large distances (up to 60cm).
Early instars are light green with waxy filaments protruding from the abdomen, and a white powder covering the entire body. Later instars lose the white powder, and red marks appear on the dorsal side of the abdomen. However, there is some debate to the specific color changes that the nymphs take on from various instars
Host Plants: Siphanta acuta is found on: banana, citrus, coffee, guava, macadamia and many ornamental plants.
Siphanta acuta has been known to eradicate large numbers of native trees in Hawaii as well as coffee and other cultivated crops (listed above under host plants). Siphanta acuta secrete a viscous honeydew liquid on the plant while it feeds. This secretion quickly becomes a culture for fungus and mold to grow on. The spread of fungus prevents the host plant from carrying out photosynthesis and can result in death of the plant or disfigurement if not treated.
The adult female Siphanta acuta lays eggs in clutch sizes of 100 that hatch within 10 to 20 days. The eggs are laid on stems or leaves of the host plant in a dome-like shape with semi-transparent cement holding the mass together. Newly emerged nymphs advance through 5 instars.
In 2002 the redbay ambrosia beetle was discovered near Port Wentworth, Georgia by chance in a survey trap. Within three years the beetle spread through the southeast U.S. and was associated with death to ambrosia and sassafras trees in Florida. Experts believe introduction of the redbay ambrosia beetle was facilitated by solid wood packing materials such as crates or pallets that the beetle was feeding on undetected.
U.S. Present: Hawaii and California but spreading east along the continental United State
U.S. Habitat: Although Siphanta acuta originated in Australia it was thought to be introduced to New Zealand and Hawaii prior to 1898. The torpedo bug was introduced to the U.S first in California and was believed to be established by 1983.
Currently, there are no known pesticides for Siphanta acuta. However, in Hawaii parasites and predators have been identifies and shown to reduce populations. Aphanomerus pusillus is a known parasite to the eggs of torpedo bugs. Chrysopa microphya is known to feed on the nymph stage of the torpedo bug and Nesomimesa antennata paralyzes the torpedo bug and uses the body as a host for nests. Also, several known coccinellid beetles feed on the eggs of the torpedo bug and Siphanta acuta is also susceptible to a parasitic fungus in wet conditions that will eradicate the pest.
Gagne, Wayne.1979. Canopy Associated Arthropods in Acacia Koa and Metrosideros Tree Communities Along an Altitudinal Transect on Hawaii Isand. Pacific Insets 21(1):56-82.
Myers, J.G. 1922. Life-History of Siphanta acuta (Walk.), the Large Green Plant-Hopper. New Zealand J.Sci. Tech. 5: 256-263.
Zimmerman, E.C. 1948. Siphanta acuta (Walker). Insects of Hawaii Volume 4: Homoptera: Flatidae. University of Hawaii Press: Honolulu. 268 pages.