Forty-five Angus steers (avg initial wt 330 kg) were individually fed for 112 d to assess the value of supplemental Zn and source on performance and carcass quality. Steers had ad libitum access to a control diet (81 ppm Zn) of 33% whole corn, 33% ground milo, 15% cottonseed hulls and 13% cottonseed meal, or this control diet with 360 mg Zn/d added from either zinc methionine or zinc oxide. Steers were slaughtered on d 114, and carcass composition was determined by specific gravity. Average daily gain and feed efficiency were not affected by dietary treatments. Steers fed zinc methionine had a higher (P less than .05) USDA quality grade than those fed the control and zinc oxide diets. Marbling score was higher (P less than .05) for steers fed zinc methionine than for those fed control and zinc oxide treatments (4.4 vs 4.0 and 4.0, respectively, where 3 = slight, 4 = small, 5 = modest). Steers fed zinc methionine tended to have more (P less than .10) external fat (13 mm) than steers fed the control diet (10 mm); steers supplemented with zinc oxide had intermediate amounts of external fat (11 mm). Steers fed zinc methionine had 10.5 and 12.8% more (P less than .05) kidney, pelvic and heart (KPH) fat than steers fed control or zinc oxide diets, respectively. The effects of zinc methionine on carcass quality grade and marbling score may be due to Zn and (or) methionine. Regardless of the mechanism, the difference represents a potential economic benefit to producers.

The western spruce budworm, Choiistoneura occidentalis Freeman, which normally passes through an obligate diapause in nature, was reared in the laboratory without diapause. The critical factor for preventing diapause appeared to be the physical environment presented to the first stage larvae. The response of C. occidentalis was flexible. The 2nd stage larvae could be made to diapause or forego diapause, depending on their rearing experience in the first stage. By eliminating diapause it was possible to rear about 7½ generations per year as against about 2¼ under normal diapause conditions. The diapause of the jack-pine budworm, C. pinus pinus Freeman, and C. lambertiana californica Powell, could be prevented by the same technique. The diapause of the spruce budworm, C. fumiferana (Clemens), could not be eliminated except after several generations of selection.

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The mountain pine beetle (Dendroctonzcs ponderosae Hopkins) is the most destructive insect that attacks lodgepole pine (Pinus con-EOrta Dougl.), a species valued for multiple uses throughtout North America. The elTective residual life of carbaryl, applied as a 2 percent suspension of Sevimol to the bark of lodgepole pine to prevent attack by mountain pine beetle, was evaluated near Dillon, Colorado. Trees (9,568) treated in 1982 under operational conditions were used to assess the efficacy of the treatment for one and two beetle flight periods after insecticide application. Estimated mortality of untreated trees was 0.91 percent compared with 0.074 percent for trees treated 16 months earlier with carbaryl. Residues of carbaryl were estimated at 359 ppm 16 months after application. When exposed to intense beetle pressure, bolts from trees treated 13 months earlier suffered fewer attacks and had shorter mean egg gallery length than did bolts from untreated trees; bolts from trees sprayed 3 months earlier sufkred no attacks. Apparently a 2 percent suspension of carbaryl applied to the bole of lodgepole pine was effective in protecting lodgepole pine from mountain pine beetle for the Right period 3 months after application and even provided protection for a second Right period 16 months after treatment.