. Bulletin. Natural history; Natural history. August 1985 Crayfishes and Shrimps of Illinois 365. Fig. 91.—Total distribution of Cambarellus shufeldtii. excavates a chamber in the mud bottom of the slough or swamp as drying occurs and then seals the top of the chamber to prevent desiccation. Life History.—Form I males are present in Illinois collections (Table 5) during most months and peak in occur- rence in December, February, and March. In Louisiana, Penn (1942, 1950) found form I males in all months except September, with peaks in January, February, and July. Presumably, mating in C. shufe
. Bulletin. Natural history; Natural history. August 1985 Crayfishes and Shrimps of Illinois 365. Fig. 91.—Total distribution of Cambarellus shufeldtii. excavates a chamber in the mud bottom of the slough or swamp as drying occurs and then seals the top of the chamber to prevent desiccation. Life History.—Form I males are present in Illinois collections (Table 5) during most months and peak in occur- rence in December, February, and March. In Louisiana, Penn (1942, 1950) found form I males in all months except September, with peaks in January, February, and July. Presumably, mating in C. shufeldtii may occur at anytime but peaks in winter in Illinois and in winter and summer in Louisiana. Females carrying eggs were found in Illinois from February to May, and peaked in occurrence in March (Table 5); females carrying young have been found in Illinois in April, June (Table 5), and July (Brown 1955). In Louisiana, females with eggs or young are jjiesenl in every month, with strong peaks in January-Mardi and June-July (Penn 1942, 1950; Lowe 1961), again suggest- ing two peaks of repiodut ti\i' activity in the southern part of the range. Nine Illinois females, mm Fig. 92.—Distribution of Cambarellus shu- feldtii in Illinois; black dots = 1972-1982 col- lections. CL, collected in February and March were carrying 47-99 (mean, ) eggs averaging mm in diameter. The re- lationship between numbers of eggs (N) and carapace length (CL) is N = — + log CL, r = Four females, mm CL, collected in April 1974 were carrying 15-74 (mean, ) young. The decline from an average of eggs to an average of young suggests a 44 percent mortality during egg and early instar stages. Penn (1942) found the number of eggs or young on a female to increase with the carapace length of the female, with females mm averaging 27 offsjiring and those 11 mm averaging 54 offsjjring. \n oxer- all average of 34 offspring per female {N = 100) in
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