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The seasonal emergence patterns of three root-infesting weevils of pine trees in Wisconsin were determined. Emergence periods were distinctly separated in the following sequence: Hylobius radicis Buchanan, Hylobius pales (Herbst), Pachylobius picivorus (Germar). The sex ratio for each weevil was 1:1, but the distribution of emerging adults per tree varied with species. Usually only one H. radicis emerged per tree, whereas the distribution of H. pales was much more clustered. Brood production within a site was directly related to elevation along a slope. This was probably caused by differential exposure to flooding. All three species can breed and develop successfully in the same tree concurrently, and there was no evidence of competition between the primary H. radicis and the secondary species. Co-occurrence generally facilitated development of the various species, suggesting that moderate-sized trees killed by H. radicis may provide a reservoir for development by H. pales and P. picivorus, which could then damage seedlings by adult feeding. Experiments with chemical lures confirm that only overwintered pine root weevils respond to olfactory cues in Wisconsin.

Male pales weevils, Hylobius pales (Herbst), were sexually immature upon emergence from their pupal cells. During the first 2 wk of adult life the concentration of sperm bundles in the testes increased, and a lumen containing a granular material began to form in the accessory glands. Most individuals had active sperm when 2 wk old. Four-week-old males had a large concentration of sperm bundles, numerous active sperm, and accessory glands entirely filled with a granular material. During mating trials 3- to 6-d-old (prereproductive) males did not transfer sperm to either reproductive or prereproductive females. Twenty percent of the 11- to 15-d-old (incipient reproductive) males transferred some sperm to reproductive females, but no sperm was transferred to prereproductive females. Eighty-five percent of the 4-wk-old (reproductive) males transferred sperm to reproductive females. The quantity of sperm transferred was quite variable. Seventy percent of the reproductive males transferred small amounts of sperm to prereproductive females. Female receptivity may influence the amount of sperm transferred by reproductive males.

The introduced basswood thrips, Thrips calcaratus Uzel, feeds on developing buds and often defoliates extensive areas of deciduous forests in the upper midwest. Little is known about the basic biology of this species. Therefore, effects of temperature and host plant on T. calcaratus development were studied. Temperature affected the duration of each life stage, except the 1st instar. Total development time and adult longevity were inversely related to temperature. Total development time ranged from 29.0 d at 15°C to 12.0 d at 30°C. The availability of pollen as a supplemental nutrient source did not enhance attraction or performance of the thrips. T. calcaratus produced the most offspring at 20°C (0.7 eggs per female per day). There is a 2-d preoviposition period before the peak of ovipositional activity. Of the 7 plant genera assayed, 2 could sustain T. calcaratus development to adulthood. Performance on linden and sugar maple was similar, except the egg stage was longer on linden. The implications of T. calcaratus development under these environmental conditions and on these alternate hosts are discussed.