Temperature effects on developmental period, survival rate, and reproductive capacity of Aphis rumicis L. were studied on Broadleaf dock and Swiss chard at four constant temperatures (17.5 degrees C, 20 degrees C, 22.5 degrees C, and 25 degrees C). The developmental time of immature stages ranged from 10.9 days at 17.5 degrees C to 6.5 days at 25 degrees C on Broadleaf dock, and 11.8 days at 17.5 degrees C to 6.5 days at 25 degrees C on Swiss chard. The total percentage of survivorship of immature stages varied from 54.2% and 67.6% 17.5 degrees C-25 degrees C on Broadleaf dock, and 49.7% and 62.4% at 17.5 degrees C-25 degrees C on Swiss chard. The largest r (m) value occurred with 0.2845 at 25 degrees C on Broadleaf dock and with 0.2785 at 25 degrees C on Swiss chard. The results obtained on this study indicated that Swiss chard was a less favorable host of the A. rumicis than Broadleaf dock. The optimal temperature for A. rumicis growth, developmental time, and reproduction was 22.5 degrees C-25 degrees C.