Herpetogramma sphingealis Handfield & Handfield

Adult male:wingspan 34–37 mm (Herpetogramma aeglealis 29–34 mm). Upperside of head, palpi (excFept tufts at base), protothoracic collar, and upperside of thorax concolourous, chocolate brown, fading to a slightly paler brown with age; antennae filiform, finely ciliate on underside, each segment concolourous dorsally with upper surface of head; upperside of abdomen concolourous with wings, except for posterior brownish-yellow tuft covering valvae; maxillary palpi, legs, and underside of head, thorax, abdomen pure white; dark-brown band (nearly width of eye on side of head) and including the top of the maxillary palpi and chaetosema gives head appearance of having a longitudinal mask; eye black with greenish bands. Forewing chocolate brown, concolourous with upperside of head, thorax, abdomen, fading slightly to a paler brown; apex acutely angled; postmedian line slightly zigzagging from costa to halfway down wing, then turning abruptly inward at nearly right angle to position below reniform spot before turning downwards and zigzagging to posterior margin of wing; no other lines visible (except sometimes a vague trace of an outward-curved antemedian line); only other marks on forewing are a white patch on fringe at anal angle, two black dots at position of orbicular and the reniform spots, a cream-coloured rectangular patch between two black dots, and a dark terminal line at base of fringe; fringe concolourous with wing except for white anal patch and slightly darker shading on veins; fringes also fading with age. Hindwing concolourous with forewing, including fringe, fringe with dirty-white shading at anal angle; no lines visible; a round (more like a lunar crescent in Herpetogramma aeglealis) black discal dot with a creamy-white irregular patch toward wing base (nearly hidden by posterior margin of forewing). Fringes of all wings even, not crenate. Underside of all wings, including fringes, a dark grey, fading to a paler whitish grey toward wing base with white at base near pure-white thorax, especially along inner margin of hindwing; creamy patch and two black dots on forewing barely visible as is discal spot of hindwing. Legs mainly pure white, sometimes with brownish scales on upperside of anterior and posterior legs. Adult female:wingspan 31–34 mm (Herpetogramma aeglealis 27–31 mm). Essentially same as for male except forewing larger, less elongated, and more square at margin; colour of wings a paler chocolate brown, transverse lines more contrasting. Hindwings as for male, but colour fading near base, sometimes showing a vague trace of a postmedian line. Genitalia. Male genitalia of Herpetogramma sphingealis differ from those of Herpetogramma aeglealis in length of aedeagus and the details of vesica. In Herpetogramma sphingealis aedeagus long, 10.0–10.6 ? as long as medial width compared to 8.0–8.8 ? in Herpetogramma aeglealis. Also, secondary pouch on subbasal diverticulum broad and rounded, but narrow and finger-like in Herpetogramma aeglealis. Spinules on surface of the basal part of the vesica minute and difficult to see in Herpetogramma sphingealis but larger and more conspicuous in Herpetogramma aeglealis. Female genitalia similar to those of Herpetogramma aeglealis, except for length of ductus bursae (0.27 ? as long as corpus bursae in Herpetogramma sphingealis, but only 0.22 ? in Herpetogramma aeglealis), this likely reflecting longer aedeagus of Herpetogramma sphingealis. Genitalic dissections of specimens of dark semi-melanic forms allow specimens to be identified as Herpetogramma aeglealis.

Herpetogramma sphingealis occurs from southern Quebec southward in eastern United States to Georgia and Louisiana and as far west as Arkansas. Christmas fern occurs from southeastern Canada southward to northern Florida and west to eastern Iowa and eastern Texas. At present, Herpetogramma sphingealis is known to occur over most of its host plant's range, and may occur over all of it. The species seems to be expanding its distribution, at least to the North. It is spreading to new localities in southern Quebec, appearing in some places that are well collected by the authors and colleagues where it had never been seen previously. For example, Mont-Saint-Hilaire has been collected by the author (LH) since 1966, Otterburn Park (Les Bosquets Hudon) since 1970 (LH), Ste-Anne-de-Bellevue (Morgan Arboretum) since 1949 (A. C. Sheppard) and since 1971 (LH), Rougemont since 1971 (LH) and St-Armand since 1982 (LH) and Herpetogramma aeglealis has been regularly found at these localities, but Herpetogramma sphingealis appeared for the first time in 2003 and in numbers since 2004, suggesting an invading species. We have not seen any specimens from other provinces in Canada, even from Ontario, although a search of areas where Christmas fern is common may be productive.