Key to instar III and instar II of known larvae of Chostonectes Sharp, 1882

1. Frontoclypeus with egg-bursters; head width smaller than 0.4 mm .......................................... instar I

- Frontoclypeus lacking egg-bursters; head width greater 0.4 mm ................................................. 2

2. Thoracic and abdominal spiracles absent.............................................................. instar II

- Thoracic and abdominal spiracles present............................................................ instar III

1 Head capsule with dark lateral bands running over frontoclypeus; lateral projections and lateral edges of nasale dark; dorsally, no distinct narrowing at base of siphon; head length less than 2.0 times greater than length of last abdominal segment.................................................................................................... C. gigas

- Head capsule with distinct dark bands outlining edge of frontoclypeus without crossing it; lateral projections and lateral edges of nasale pale; distinct narrowing of last abdominal segment separating its proximal part from siphon (Fig. 3B); head length more than 2.2 times greater than length of last abdominal segment.............................................. 2

2 Width of spatulate apex of nasale more than 2 times (more than 1.5 times for instar II) greater than minimum width of nasale (Fig. 2C); less than seven tubercles on ventral side of lateral projections of nasale......................... C. nebulosus

- Width of spatulate apex of nasale less than 1.5 times (less than 1.4 times for instar II) greater than minimum width of nasale; more than eight ventral tubercles on lateral projections of nasale (Fig. 3C)............................... C. johnsonii