Distribution. Striped grass looper is native to the western hemisphere, where it occurs commonly from the southern United States south to Brazil, including the Caribbean. On occasion, it is reported from as far north as Labrador and as far south as Argentina, but its occurrence always is limited to east of the Rocky Mountains and Andes Mountains. In the United states it is damaging only in the Gulf Coast region, where warm weather favors the survival of this tropical insect. Other species of the genus occur in the same area, but are not thought to be important pests.
Host Plants. As implied by its common name, this species feeds only on grasses. Several crops support striped grass looper, including bahiagrass, Bermuda-
grass, corn, guineagrass, millet, oat, pangolagrass, paragrass, rice, ryegrass, St. Augustine grass, Sudan grass, sugarcane, sorghum, and wheat. Among vegetable crops, only sweet corn is injured. Wild grasses reported as hosts include barnyardgrass, Echinochloa crusgalli; bluestem, Andropogon spp.; crabgrass, Digi-taria spp.; goosegrass, Elusine indica; Johnsongrass, Sorghum halepense; panicum, Panicum spp.; and others.
Natural Enemies. Although there is extensive information on natural enemies affecting striped grass looper in Central and South America (e.g., Cave, 1992), data from North America are limited. Hall (1985) reported larval and pupal parasitism rates of 7.044.6% with a mean value of 29% in southern Florida sugarcane fields. Sarcophagid and tachinid flies seem to be most important, and include Sarcodexia sternodon-tis Townsend and Sarcophaga sp. (both Diptera: Sarco-phagidae); Archytas marmoratus (Townsend), Attacta brasiliensis Schiner, Belvosia bicincta Robineau-Desvoidy, Chetogena sp., Eucelatoria armigera (Coquil-lett), Euphorocera claripennis (Macquart), and Lespesia aletiae (Riley) (all Diptera: Tachinidae). Among the wasp parasitoids are Brachymeria ovata (Say), B. robusta (Cresson), Spilochalcis sanguineiventris (Cresson), Spilo-chalcis n. sp. (Hymenoptera: Chalcididae); Copidosoma truncatellum (Dalman) (Hymenoptera: Encyrtidae); Apanteles scitulus Riley, Meteorus autographe Muese-beck, Microplitis maturus Weed (Hymenoptera: Braco-nidae); Coccygomimus aequalis (Provancher), Enicospilus purgatus (Say), Gambrus ultimus (Cresson) (Hymen-optera: Ichneumonidae); and Trichogramma sp. (Hymenoptera: Trichogrammatidae). The ectoparasi-tic nematode, Noctuidonema guyanense (Nematoda: Aphelenchoidea) is found on the bodies of moths (Rogers and Marti, 1993), but causes few detectable effects on the insects.
Predation may be an important factor, if overlooked element in striped grass looper population dynamics. In addition to predation by such usual predators as lady beetles (Coleoptera: Coccinellidae), there are frequent reports of predation by Anolis spp. lizards and songbirds such as eastern meadowlark, Sturnella magna, and redwing blackbird, Agelaius phoeniceus.
Pathogens associated with striped grass looper include the fungi Beauveria bassiana and Nomuraea rileyi and a virus, but the importance of these microorganisms has not been determined.
Life History and Description. Striped grass looper is found throughout the year in southern Florida and Puerto Rico; elsewhere in the United States it is abundant principally during late summer and autumn. There is no period of diapause in this species. Duration of the complete life cycle has been given by most authors as 40-60 days, though it varies with tempera ture. The developmental threshold for this insect is reported to be 13.7°C, and it tolerates temperature of 20-30° C readily. Thus, several generations occur annually in the south.
Striped grass looper larva.
Striped grass looper larva.
Sanchez (1981) reported a mean pupal period of 6.7 days at 30°C.
Adult. The moths are grayish tan or gray in general color, with dark lines and circular markings. Like other Mocis spp., striped grass looper males have a dark spot on the lower margin of the forewing about one-third the distance to the outer margin. However, most specimens of M. latipes bear a dark area or spot at about the mid-point along the outer margin of the forewing, a character that helps distinguish M. latipes from the other Mocis spp. Striped grass looper moths superficially resemble adults of velvetbean caterpillar, Anticarsia gemmatalis Hübner. However, the transverse stripe across the forewing of velvet-bean caterpillar moths terminates at the apex, whereas in striped grass looper it runs parallel to the outer wing margin (Gregory et al., 1988). The wingspan of striped grass looper moths is 35-40 mm. Adults fly most actively during the early evening hours, though mating frequency is highest near midnight. Adults survive for 10-20 days when provided with food. They typically produce 200-300 eggs.
The biology of striped grass looper was summarized by Genung and Allen (1974), Reinert (1975), and Dean (1985). Larval and pupal descriptions can be found in Ogunwolu and Habeck (1979). Striped grass looper is included in the key to looper pests of vegetables found in Appendix A.
Over 40 species of grasses are fed upon, but other plants seem to be relatively immune to attack. The first and second instars feed on epidermal leaf tissue only, but later instars notch the leaf margins. When abundant, larvae completely defoliate grass plants, leaving only the midribs and stems. Larvae feed at night, and remain curled on the soil or in clumps of grass during the day. Although not regularly abundant, during some seasons they can be devastating pests, causing high levels of defoliation.
Moths are attracted to light (Gregory et al., 1988) and to sugar-based baits (Landolt, 1995). It is also possible to attract males to pheromone formulations, though velvetbean caterpillar may be attracted to the same chemicals (McLaughlin and Heath, 1989; Landolt and Heath, 1989). Larvae often are difficult to detect because they hide during the day, and their presence is observed only following damage. Grass weeds are often the site of initial infestation in crop fields, so grass weeds should be destroyed to dis courage moths from ovipositing within crops. If larval numbers are high or damage is imminent, application of insecticides to crop foliage is recommended.
Was this article helpful?