DISTRIBUTION:

Nyceryx riscus (wingspan: 50-58mm; females larger than males) flies from Belize and Mexico, the specimen type locality, to Costa Rica;
Venezuela: (Barinas (JRAC));
and further south to Bolivia: La Paz (1100m) and (Argentina: Misiones (EB)).

Nyceryx riscus, Yacutinga, Misiones, Argentina,
February 2008, courtesy/copyright Ezequiel Bustos.

FLIGHT TIMES:

Moths are probably on the wing in just about every month, but with no records for March in Costa Rica.

Nyceryx riscus, Grande Papagayo, north-west coast of the Tamarindo Peninsula, Costa Rica,
near Panama, September 17-20, 2008, courtesy of Tony James.

ECLOSION:

Adults eclose, usually within two to four weeks from pupation date.

SCENTING AND MATING:

Females call in the males with a pheromone released from a gland at the tip of the abdomen.

Females are active just after midnight with males beginning night flight around 1:00 am.

Nyceryx riscus female, Costa Rica, courtesy of Dan Janzen.

EGGS, LARVAE, PUPAE:

Larvae feed on Xylophragma seemannianum.

I take the following quotes from Dan Janzen's notes:

"The tail horn is solid green with well-developed bumps. The body is a yellowish/pale green; the lateral diagonal slashes are pale yellow. The head is pale green with a trace of blue wash, and the base of last and second to last pair of legs is black with dark brown center and red/orange lateral margins to yellow around base, like a Perigonia spp. caterpillar. These caterpilars save turds and make a pupation chamber in soil in a surface pit. The pupa has no tongue case; note that the tail horn of Perigonia spp. is also slightly bumpy - extremely similar caterpillar to Perigonia spp."

"Larvae can be found eating very mature leaves. There is no dorsal green line and very faint yellow dotting (like Protambulyx strigilis) and the side slashes are yellow-green and faint, but the tail slash is bright yellow green, not white and there are no accompanying lines; front legs have a strong yellow lateral patch and then black and then red at very base; shows yellow quite strongly when exposes; green tail horn; very active caterpillar (other one was also), and the most running sphingid larva I know; when eating sits below leaf along midrib and eats off flat end of leaf; when touched, thrashes violently from side to side; when being photographed was on a horizontal leaf, and produced one turd, 2 cm from its middle. After about one minute, got restless and wiped mandibles repeatedly on midrib and then stretched searching; when found turd, picked it up in mandibles and turned and straightened and released (dumped); turd rolled near and the caterpillar repeated this over and over; clearly removing it from vicinity and clearly smelled its presence."

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