Larva a large semireductus- or plumosus-type, anterior ventral tubules with an inflection in the basal half (Butler, unpubl.). Gular region dark, frontoclypeus pale. Mentum with pointed teeth and of type I; centre tooth relatively narrow, side teeth well separated (type IV or sometimes tending to type II). Pectin epipharyngis with about 12 broad teeth. Antenna with relatively long narrow basal segment, about 4.4 times as long as wide.
Cytology: 4 pairs of relatively short chromosomes with the
thummi arm combination AB, CD,
EF, G. Banding pattern often unclear.
Arm G usually unpaired, with a large virtually terminal nucleolus -
often with a constriction
just before the nucleolus; at least one Balbiani ring (BR) near the
other end. No nucleoli
in other chromosomes but a BR often developed in arm B, generally
near the 4 characteristic bands near the centromere, but sometimes
towards the end of the arm due to polymorphism. Arm A
generally with sequence h'A2. Polymorphism
in arms A, B, D, but also rarely in E (California). B
chromosomes found in two populations.
h'plu A2: 1 - 2c, 10 - 12a, 13ba, 4a-c, 2g-d, 9 -
4d, 2h - 3, 12c-b, 13c - 19:
ie. as entis
A4
n'plu A9: 1 - 2a, 17 - 14, 13f-c,
12bc, 3 - 2h, 4d - 9, 2d-g, 4c-a, 13ab, 12a - 10, 2cb, 18 -
19
h'plu B1: 1 - 4c, 20c - 23a, 20b - 19, 15 - 17, 6d -
4d, 6e - 8b, u, 19a - 18, 8c-13, u, 23b - 28
BR proximal, near the 4 characteristic bands; puff in
group 7 not developed.
h'plu B2: approx. 1 - 4c, 20c - 23a, 20ba, u, 13 - 8c, 18 - 19a, u, 8b - 6e, 4d - 6, 17 - 15,
19a-i, 23b - 28
BR distal due to large inversion of h'B1 (heterozygous
only)
n'plu B4: BR proximal, inversion of region 5-10
(heterozygous only)
n'plu B5: BR about middle of arm due to complex
inversion (heterozygous only)
h'plu C2: 1-2c, 6c-f, 7a-d, 16-17a, 6hg, 11d-12,
4-6b, 11c-8, 15-13, 3-2d, 17b-22
h'plu D2: 1-3,, 10b-e, 4-7, 18a-d, 8-10a, 13a-11,
13b-17, 18e-24
n'plu D6: 1-3, 10b-e, 4-7, 18g-e,
17-13b, 11-13a, 10a-8, 18d-a, 19-24
n'plu D7: 1-3, 10b-e, 4-7, 15d-13b, 11-13a, 10a-8, 18d-a, 15e-17, 18e-24
n'plu D8: 1-3, 10b-e, 4-7, 18ab, 11-13a, 10a-8, 18dc, 13b-17, 18e-24
n'plu D9: 1-3, 10b-e, 4-7, 18ab, 9-8, 18dc, 10a, 13a-11, 13b-17, 18e-24
p'plu E1: 1 - 3e, 10b - 3f, 10c - 13
(Butler et al.
1998b)
h'plu E2: 1 - 2, 4e-h, 10b - 5,
3e-a, 4d - 3f, 10c - 13
h'plu F1: 1a-d, 6 - 1e, 7 - 10, 17 - 11, 18 - 23
h'plu G1: as Palearctic populations
Found: Numerous lakes in Canada and U.S.A.:
Alberta - South Baptiste Lake.
British Columbia - Deer Lake, Near Opposite
Crescent, Bechers Prairie, Cariboo and
Chilcotin Parklands.
Ontario - Milhaven Bay; White Lake, 3 Mile
Bay.
Saskatchewan - Lake Waskesiu, Prince
Albert National Park.
Alabama - Farm pond, Auburn;
California - Clear Lake; Lake Merced, San
Francisco.
Indiana - Crooked Lake, Angola
Co.; Crooked Lake, Noble Co.; Manitou Lake; Shafer Lake; Sylvan Lake;
Kentucky - Lake, Campbell Co.;
Minnesota - Lake Itasca; Lake Christina, Douglas
Co.
New
Mexico - Eagle Nest Lake, Colfax Co.; Upper Abbot Lake,
Harding Co.; Lower Abbot
Lake, Harding Co.
North
Dakota - Dead Colt Creek Dam, Ransom Co.;Larimore Dam, Grand
Forks, Co.; Red
Willow Lake, Griggs Co.; Silver Lake, Sargent Co.
Oklahoma - University of Oklahoma Biological
Station, Willis, Marshall Co.
South
Dakota - Lake Kampeska;
Wisconsin - East Horsehead Lake, Onieda Co.; Grand
Portage Lake, Iron Co.; Green Lake;
Little Green Lake, Green Lake Co.; Lake Kengonsa, Dane Co.; Lake
Onalaska, 1m. NW
La Crosse; Lake Wingra, Dane Co.; Murphy's Creek, Madison, Dane Co.;
Pepin Lake;
Pine Lake; Pleasant Lake; Yellow Lake.
Lakes up to considerable depths (up to 23 m).
North American material has been described as C. vancouveri by Michailova and Fischer (1986), but it is almost certainly a synonym of C. plumosus (Butler et al. 1999) Some workers (e.g.Hilsenhoff and Narf 1968) have suggested the existence of more than one species on ecological grounds. Cytological studies indicate the presence of C. entis, separated in part by differences in polymorphism and location of Balbiani rings. The two species are often found in the same lake. The form with 2 generations per year in general has better quality chromosomes. The cytology of North American C. plumosus has been described by Butler et al. (1999, 2000).