Larva a medium sized thummi-type. Gular region dark, frontoclypeus and other parts of the head capsule darkened. Mentum (Fig. c) with pointed teeth; fourth laterals in line with the third and fifth laterals (type I); centre tooth moderately broad with almost parallel sides, c2 well seperated, notches almost vertical (type II). Ventromentum (Fig. d) with about 43 striae. Pecten epipharyngis (Fig. a) with about 14 irregular teeth. Mandible (Fig. e) with third inner tooth pale and only partially separated (type II).
Cytology: 4 pairs of chromosomes with the
thummi arm combination AB, CD, EF, G. Centromere
regions distinctly heterochromatic.
Arm G normally paired with a subterminal nucleolus and generally with
2 Balbiani rings
near the centre, the second followed by a constriction and a dark
band. No nucleoli
in long arms. Sequences described in Europe as C.
thummi (=riparius). No chromosomal
polymorphism reported in North America.
rip A1: 1 - 19
rip B1: 1 - 28
rip C1: 1 - 22
rip D1: 1 - 24
rip E1: 1 - 13
rip F1: 1 - 23
Found: Manitoba -
Southern Indian Lake (Rosenberg et al.,
1984).
Ontario - Amherstview; Stratford, Windsor.
Northwest Territories - Smoking Hills (Jernelov et al. 1981)
Kansas - Mill creek, nr. Craig, Johnson Co.
Maryland - Baltimore, Baltimore Co.
Missouri - Columbia, Boone Co.
New
York - Ithaca, Tomkins Co.
South
Dakota - 1 m W, 2 m N Yankton, and 3 m W Yankton, Yankton
Co.
Tennessee - Oak Ridge, Anderson Co.
Wyoming - Hawk Springs, Goshen Co.
Creeks and pools, particularly where polluted.
Larvae described by Johannsen (1938) as C. militaris. Cytology given by a number of authors in North America (e.g. Poulson and Metz 1938, Blaylock 1971) and in Europe as C. thummi Kieffer (e.g. Keyl and Keyl 1959, Devai et al. 1989).