Objective The trial was conclucted to understand the damage habits of the Polychrosis cunninhamiacola and identify the main morphological characteristics of male and female pupae and adults.

Method The tops with larvae were collected from the Cunninghamia lanceolate forests and observed in insectarium combined with the observation outdoors. The behavior habits and morphological characters of larvae, male and female pupae and adults of P. cunninhamiacola were observed.

Result The larvae of P. cunninhamiacola had shoot-transferring behavior habits and damaged the tops of C. lanceolata. When the larvae reach maturity, they pupated in the tip of a branch. Most pupae completed eclosion in the wee hours or in the morning, and the egg were scattered on the back of blades. The pupa was obtect and the new pupa was beige. The male pupae had a longitudinal genital cleft on the segmental venter of the ninth abdominal segment, with a hemispherical protuberance on each side. The distance between anal cleft and genital cleft was 80-170 μm. The genital cleft of female pupa was on the eighth abdominal segment and there was no hemispherical protuberance on either side of the cleft. The distance between anal cleft and genital cleft was 270-360 μm. The hapis at the tail of the male adult was obvious with forked or forceps shaped and densely scaly. The female adult had a kidney-shaped, orange ovipositor on its tail.

Conclusion The damage behaviors of P. cunninhamiacola(such as shoot-transferring)were understood, male and female pupae were identified by the the characteristics such as pupa's abdominal segment and protuberance, and male and female adults were identified by adult's hapis, ovipositor and other characteristics, which provided a theoretical basis for the monitoring and control of P. cunninhamiacola.