Cotton cutworm

Scientific name

Spodoptera litura (Lepidoptera: Noctuidae)

Other common names

tobacco cutworm, oriental leafworm moth, cluster caterpillarcaterpillar:
common name for larval lepidopterans (butterflies and moths)
, tropical armyworm

Similar species

beet armyworm, Spodoptera exigua

Egyptian cotton leafworm, Spodoptera littoralis

southern armyworm, Spodoptera eridania

For definitive identification, it is necessary to dissect adult male internal parts.

Distribution

United States: Frequently intercepted by agricultural agents in U.S. ports but only reported from Florida and Hawaii. Currently being eradicated in Florida.

Worldwide: Asia, specifically Cambodia, China, Japan, India, Pacific Islands, and Guam. Also found in the northern two-thirds of Australia.

Native to Asia.

Diagnostic characteristics

Adults

• 15 - 20 mm (0.59 - 0.79 inches) in length.
• 30 - 38mm (1.18 - 1.5 inches) wingspan.
• Brown wings with cream streaks crisscrossing on the forewingforewing:
  the anterior (closest to the head) pair of wings in insects
  .
• Hindwings are silvery white.

Larvae

• Six larval instars.
• Young instars are green with a dark underside.
• 3rd instarinstar:
  immature stages (larva or nymph) of insects in between molts
  develops red and yellow strips the length of the caterpillarcaterpillar:
  common name for larval lepidopterans (butterflies and moths)
  .
• 4th and 5th instarinstar:
  immature stages (larva or nymph) of insects in between molts
  caterpillars become green with thin yellow lines and black triangle-shaped spots.
• Last instarinstar:
  immature stages (larva or nymph) of insects in between molts
  turns a dark brownish-red color with 4 yellow triangles on the mesothoraxmesothorax:
  the second or middle segment of the thorax
  .

Eggs

• Egg masses 4 - 7 mm (0.16 - 0.27 in) in diameter made up of 200 - 300 eggs.
• Cream to golden brown.
• Covered by light brown abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  hairs from the female.

Hosts

Citrus hosts:

All Citrus species and their hybrids.

Non-citrus hosts:

Broad host rangehost range:
the range of species that a particular organism can feed on to achieve successful growth and reproduction
, known from over 100 host plants that include weeds as well as vegetable, field, and flower crops. A partial list includes:

• all cruciferous vegetables, Brassica oleracea
• Acacia spp.
• African oil palm, Elaeis guineensis
• alfalfa, Medicago sativa
• amaranth, Amaranthus spp.
• banana, Musa spp.
• bean, Phaseolus vulgaris
• corn, Zea mays
• cotton, Gossypium hirsutum
• eggplant, Solanum melongena
• Fuchsia spp.
• Geranium spp.
• Lantana spp.
• lettuce, Lactuca sativa
• mango, Mangifera indica
• peanut, Arachis hypogaea
• sorghum, Sorghum spp.
• strawberry, Fragaria spp.
• sugarcane, Saccharum spp.
• tomato, Solanum lycopersicum

Host damage

Flowers

Sometimes eaten by mature larvae.

Fruits

Sometimes eaten by mature larvae.

Leaves

Young larvae will skeletonize the leaves (only the veins remain). Mature larvae will eat the whole leaf.

Biology

Adults are nocturnal and live 8 - 10 days. During her lifetime, a female can produce over 1000 eggs. Eggs are laid in masses and covered by scales on the underside of leaves. Larvae feed at night from the underside of the leaf and curl into a spiral when disturbed. Larvae progress through six instars before dropping from the plant to pupate underground in an earthen cell. Average life cycle is 25 - 31 days.

Comments

Based on host planthost plant:
the plant the provides sustenance for an insect
and climate preference of the moth, it could live in 48% of the continental United States.

References

Espinosa, A. and A.C. Hodges. 2009. Spodoptera litura Bugwood Wiki fact sheet. (http://wiki.bugwood.org/Spodoptera_litura).

(NAPIS) National Agricultural Pest Information System. Purdue University. 2012. Survey status of cotton cutworm - Spodoptera litura (all years). (http://pest.ceris.purdue.edu/map.php?code=ITBCFMA&year=alltime).

Schreiner, I. 2000. Cluster caterpillars (Fabricious).(http://www.ctahr.hawaii.edu/adap/Publications/ADAP_pubs/2000-3.pdf).

Zhongshi, Z., C. Zepeng, and Z. Xu. 2010. Relations between air temperatures and mating behaviour of Spodoptera litura adults in nighttime in the tobacco field. Afr. J Ag. Res. 5(21): 2994-2996. (http://www.academicjournals.org/ajar/pdf/pdf%202010/4%20Nov/Zhou%20et%20al.pdf).

Authors

Weeks, J.A., A.C. Hodges, and N.C. Leppla