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85 clear streams as well as in medium and large warmwater streams. They were not observed to burrow in Iowa but they did excavate cavities under flat stones. 189 Larger Rusty crayfish were found in the deepest parts of pools among cobbles whereas small specimens used the shallows that had gravel bottoms. 124 They are not native to Nebraska but are now found in two lakes in Omaha. Benson Park Lagoon is a fairly turbid, mud-bottomed pond. During my last visit in the late summer of 2015, I had little difficulty collecting several with a dip net. The second lake, at Lakeside Hills, is clearer, also with a mud-bottom, has extensive shoreline rock riprapping. The Rusty crayfish in this lake are using the riprap along with the native Northern crayfish. BEHAVIOR Laboratory studies found that the Rusty crayfish was able to dominate over the Spinycheek crayfish and got the best shelters. 132 In an intensely studied lake in Wisconsin, Rusty crayfish were able to disperse around the lake at the rate of 0.68 km/year. 251 REPRODUCTION The mating season of the Rusty crayfish is early fall (September/October) when temperatures begin to drop. 124,189 The majority of females lay their eggs at one year old in April or May though a few did so in October. 189 Eggs take some 20 days to hatch and the young are released about five days after this. Egg counts increase as the female gets larger so can range from 54 (34 mm CL) to 357 (70 mm CL). 191 Males typically molt from mature Form I to immature Form II in late spring then back to Form I in late summer though Form I males have been collected in every month except May. 189, 228 In one study, of 1,188 Rusty crayfish collected, almost 57% were males. 124 The Rusty crayfish does have a reproductive advantage over many other crayfishes in that it can begin breeding earlier in the spring when temperatures rise above 4 C. 11 FEEDING AND SPECIES INTERACTIONS It has been noted that several crayfishes, including the Rusty crayfish, will reduce or eliminate aquatic vegetation in lakes. 44, 141, 203, 251