. Bulletin. Natural history; Natural history. August 1985 Crayfishes and Shrimps of Illinois 115 following one summer's growth. Prins (1968) studied O. rusticus in a stream in Kentucky and found that mating peaks in September and Octo- ber, females oviposit from February through June at about 22-24 months, eggs hatch in May after being carried by the female for 4-6 weeks, young remain attached to the mother for 3 weeks {through April and May), sexual maturity is reached at about 15 months (about 18 mm CL), the sex ratio among juveniles is 1:1, and the species reaches a maximum longevity of abo
. Bulletin. Natural history; Natural history. August 1985 Crayfishes and Shrimps of Illinois 115 following one summer's growth. Prins (1968) studied O. rusticus in a stream in Kentucky and found that mating peaks in September and Octo- ber, females oviposit from February through June at about 22-24 months, eggs hatch in May after being carried by the female for 4-6 weeks, young remain attached to the mother for 3 weeks {through April and May), sexual maturity is reached at about 15 months (about 18 mm CL), the sex ratio among juveniles is 1:1, and the species reaches a maximum longevity of about 3 years and a maximum CL of 45 mm. Counts of ovarian eggs in 43 females ranged from 54 to 357. The smallest female with eggs attached (55 eggs) was 17 mm CL; _the largest, with 231 eggs, was 38 mm CL. The relationship between the number of eggs (N) and carapace length (L) of 49 females was N = + IL, with r = The species feeds mainly on plants and detritus and has been observed feeding out of water along the banks. During winter, O. rusticus typically burrows into stream banks and into interstices in the substrate. Form I males have been found in July and August in Ontario (Crocker Sc Barr 1968), in June in Maine (Crocker 1979), and in July and September in Iowa (Phillips 1980). Females in berry were collected in April in Iowa (Phillips 1980). Busch (1940) found that it took 20 Jays for eggs to hatch at 20°-22°C. .\mong the nine Illinois collections (made from May through September), form I males ( mm CL) are present in August and September. No ovigerous females were found. Some Illinois specimens approach the maxi- mum size recorded for the species; the largest Illinois male (form II) is mm, CL. and the largest female is mm Page Orconectes stannardi (Fig. 148) Orconectes stannardi Page 1985 Description.—R(jstrum excavated; well-developed median carina; long acumen; margins moderately thick. subparallel, slightly converging me- dially,
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