Micrathetis triplex (Walker) 1857

Laphygma triplex Walker, 1857, List of the Specimens of Lepidopterous Insects in the Collection of the British Museum, 11:721.

Laphygma spilomela Walker, 1865, List of the Specimens of Lepidopterous Insects in the Collection of the British Museum, 32:648.

Galgula contraria Herrich-Schäffer, 1868, Corresp.-Blatt Zool.-Min. Ver. Regensburg, 22:153.

Caradrina conviva Harvey, 1876, Canad. Ent., 8:6.

Caradrina subaquila Harvey, 1878, Canad. Ent., 10:57.

Athetis minuscula Barnes and McDunnough, 1913, Contrib. Nat. Hist. Lepid. N. Am., 2(3):115.

Micrathetis benjamini Draudt, 1926, in Seitz, W., Gross- Schmetterlinge der Erde, 7:262, pl. 38, row b.

Diagnosis: Micrathetis triplex is one of the commoner species of the family Noctuidae in the drier tropical regions of the New World. It is also one of the most variable in color and size. The species is on the small side for a noctuid. The forewing color is basically gray, but if often suffused with dark gray, dull purple, or dull orange or orange-brown. The maculation is not terribly distinct, but the most distinctive features are a black filled reniform spot and a postmedial line consisting of two widely separated series of black dots. The antemedial line, when visible is a highly irregular, obscure black line. The orbicular spot is absent, or if present, is at most a small black dot. The subterminal line is a very diffuse patch, primarily indicated by a distinctly lighter terminal area. The terminal line usually consists of a series of black dashes which are sometimes fused together into a black line. The fringe is suffused with dark gray. The hindwing is white in both males and females, although a few individuals have a slightly amount of gray suffusion along the outer margin. The palpi have a dark patch on the outer side of the second segment and this patch contrasts with the white apex of the second segment and the entire third segment. The distinctive features of the male and female genitalia were described in the generic description. I have not made an exhaustive study of the neotropical material I have attributed to this species, and possibly one or more other species remain hidden within the material identified as triplex.

Distribution: This species has a wide distribution in the tropical and subtropical regions of the New World. Although not based on an sort of rigorous observations, the species seems to be commonest in drier types of habitats such as shrub and grassland rather than tropical forest. The species occurs throughout Central America and the Antilles. It occurs throughout much of South America, but based on scattered material has a patchier distribution than in the more northerly parts of its range. In the United States the species is abundant in eastern Texas and southern Florida. Micrathetis triplex has been taken as far north as eastern Kansas. There is a distinctive and isolated population of triplex in southern California.
This is a variable species. The variability is a combination of three factors; color, size, and the distinctness of the maculation. On the whole males are smaller, grayer, and more distinctly marked than females. This does not always hold, however. Females on the whole tend to be darker than the males and are often strongly suffused with dark gray. Forewing color in both males and females can be light gray, rusty orange, dark gray, or flesh-colored and all shades in between. In the male genitalia there is variation in the spiney process of the valve.
There is one very distinctive and isolated population in triplex, the species in the drier areas of Southern California. This population is geographically isolated from the rest of the North American range of triplex. The population is consistently dull orange to flesh colored and seldom has the primary gray color of the species over the rest of its range. Within the California population there seems to be somewhat more variation in size than in other populations. Although I suspected that this might prove to be a distinct species, I can find not significant differences between the California populations and the species elsewhere in its range. This California population is superficially much more similar to carnicolor than to nominate triplex both in size and coloration. So far the two can be distinguished by range and of course the male and female genitalia. On the whole carnicolor is a slightly larger species, and the maculation of the forewing is not as distinct in carnicolor giving the species a smoother, less rough appearance. A reddish form occurs in carnicolor that is not found in Californian specimens of triplex.

The adults have been collected throughout the year in Central and South America. In the United States adults are commonest in September, October, and November in Texas and Florida, but scattered specimens have been taken throughout most of the rest of the year. The California population has been collected during most months of the year, but again appears to be commonest during the fall months.

Identification Quality: Excellent

Larva: Unknown

Foodplants: There are specimens in the USNM reared from sweet potato [Ipomoea batatas (Convolvulaceae)]. There is also an adult reared from "pupae found in the roots of Convolvulus (Convolvulacae).

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