Spodoptera mauritia

Status

ADVENTIVE

Taxonomy

Spodoptera mauritia (Boisduval, 1833)
Higher taxonomy: Noctuidae: Prodeniinae
Common name: lawn armyworm

Note: prior to 1938, Spodoptera exempta had been misidentified as S. mauritia in Hawai‘i. See Swezey (1938)Swezey (1938):
Swezey OH. 1938. Identity of the nutgrass armyworm in Hawaii. Proceedings of the Hawaiian Entomological Society. 10(1):75–76. for an explanation. Zimmerman (1958)Zimmerman (1958):
Zimmerman EC. 1958. Insects of Hawaii, Volume 7. Macrolepidoptera. University of Hawaii Press, Honolulu. 542 pp. identified the subspecies present in Hawai‘i as S. m. acronyctoides Guenée, 1852, but Pogue (2002)Pogue (2002):
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202. did not recognize any subspecies.

Overview

Spodoptera mauritia is by far the most common species of Spodoptera in Hawai‘i today. It was first detected in 1953 (Zimmerman 1958Zimmerman 1958:
Zimmerman EC. 1958. Insects of Hawaii, Volume 7. Macrolepidoptera. University of Hawaii Press, Honolulu. 542 pp.). Earlier reports of S. mauritia in Hawai‘i were based on misidentifications of S. exempta (Swezey 1938Swezey 1938:
Swezey OH. 1938. Identity of the nutgrass armyworm in Hawaii. Proceedings of the Hawaiian Entomological Society. 10(1):75–76.). It is a common pest of turf and pasture grasses.

Adult Recognition

A detailed description of Spodoptera mauritia is available in Pogue (2002)Pogue (2002):
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202..

Spodoptera mauritia is a medium-sized noctuid (forewing lengthforewing length:
the distance of the forewing in a straight line from the base to the tip of the apex
12–18 mm) characterized by a pale brown ground color, a distinctive a white diagonal streak across the forewingforewing:
the front wing of an insect; the wing attached to the second segment of the thorax (the mesothorax)
in males, and a kidney-shaped reniform that is typically filled with black scales. The orbicular spotorbicular spot:
a round or oval spot located in the middle of the discal cell of the forewing, between the antemedial and median lines
is rounded, filled with pale scales in males, brown in females. The hindwinghindwing:
the back wing of an insect; the wing attached to the third segment of the thorax (the metathorax)
is white, darker distally and with darker scales along the veins.

Larval Morphology

Head brown to olive brown, pronotal shield brownish with three narrow, pale yellow or white stripes. Body color variable, dark gray to dark green. Middorsal stripe faint, irregular, darker than dorsolateral stripe, purplish. Dorsolateral band predominantly grayish, but variable. Dorsolateral stripe pale yellow to light reddish brown. Lateral band grayish with a yellow or greenish tinge. Lateral stripe often interrupted, pale. Spiracular band darker than lateral band, purplish brown to reddish. Subspiracular band pale yellowish to light reddish brown; spiracles black (Pogue 2002Pogue 2002:
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202.).

Similar Species

Spodoptera mauritia is similar to other species of Spodoptera in Hawai‘i but can be easily identified by the large scale tufts of the forelegs of males. The two tibial spursspur:
a moveable spine; often refers to an enlarged or otherwise modified spine on the legs of some moths
on the male midleg are roughly equal in length.

Larvae of S. mauritia are very similar to S. exempta but can be identified by "the reticulate spiracular band which lacks white or light colored spots caudad to the spiracles," which are present in S. exempta (Pogue 2002Pogue 2002:
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202.). Additionally, in S. mauritia "the frons is yellowish brown contrasting to the brown head; in S. exempta the frons is dark brown and concolorous with the head" (Pogue 2002Pogue 2002:
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202.).

Distribution

Spodoptera mauritia is widely distributed in Sub-Saharan Africa, southern Asia, Australasia, and throughout the southern Pacific. It also occurs in Madagascar, the Seychelles, and Mauritius in the Indian Ocean (Pogue 2002Pogue 2002:
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202.). 

In the Hawaiian Islands, Spodoptera mauritia is a common, widely distributed species. It is known from Kaua‘i, O‘ahu, Moloka‘i, Maui, Hawai‘i, Midway, Pearl and Hermes Atoll, and French Frigate Shoals (Nishida 2002Nishida 2002:
Nishida GM. 2002. Hawaiian terrestrial arthropod checklist. Fourth Edition. Bishop Museum Technical Report 22. 313 pp.). Though not known from Lānaʻi, it probably occurs there as well. It primarily occurs in low elevation residential and agricultural settings, it can be present in low numbers in dry, mesic, and wet forests at elevations up to 1300 meters (UHIM collectionUHIM collection:
UHIM collection. Based on identified specimens in the collection of the University of Hawaii Insect Museum, Honolulu, HI).

Biology

Spodoptera mauritia predominantly feeds on plants in the families Poaceae and Cyperaceae. Over 40 host species are known. The most agriculturally important hosts include rice (Oryza sativa L.), millet (various Poaceae), sugarcane (Saccharum spp.), corn (Zea mays L.), sorghum (Sorghum bicolor (L.) Moench), and pasture grasses (Pogue 2002Pogue 2002:
Pogue MG. 2002. A world revision of the genus Spodoptera Guenée (Lepidoptera: Noctuidae). Memoirs of the American Entomological Society. 43:1–202.). A few non-monocot hosts are known, but these require investigation.