The wheel bug Arilus gallus Stål (Hemiptera: Reduviidae) is a native American assassin bug that has been recorded preying on insect pests of coffee in Colombia. To provide information to support conservation biological control using this species, life-history parameters for A. gallus were investigated. Arilus gallus was reared under laboratory conditions at Cenicafe, on Galleria mellonella Linnaeus (Lepidoptera: Pyralidae) as prey. All immature stages are described and illustrated for the first time. To obtain fecundity parameters, we used 1,818 eggs of the first generation (F₁) oviposited from 19 pairs of adults. The mean number of eggs per female was 182.53 ± 7.15, derived from a mean of 1.68 egg masses per female. The egg incubation period was 27.52 ± 1.15 days; egg hatch rate was 80.66%; mean duration from egg to adult was 112.46 ± 5.5 days; and rate of survival to the adult stage was 9.69%. The longevity of adults was 109.66 ± 10.41 days for females and 89.4 ± 8.74 for males. The five immature instars can be distinguished by differences in several anatomical features, including the progressive increase in body size and the color of the abdomen and legs.