The northern corn rootworm, Diabrotica barberi Smith & Lawrence, has a univoltine life cycle that typically produces one generation a year. When rearing the northern corn rootworm in the laboratory, in order to break diapause, it is necessary to expose eggs to a five month cold period before raising the temperature. By selective breeding of the small fraction of eggs that hatched without cold within 19–32 days post oviposition, we were able to develop a non-diapausing colony of the northern corn rootworm within five generations of selection. Through selection, the percentages of adult emergence from egg hatch without exposure to cold treatment significantly increased from 0.52% ± 0.07 at generation zero to 29.0% ± 2.47 at generation eight. During this process, we developed an improved method for laboratory rearing of both the newly developed non-diapausing strain as well as the diapausing strain. The development of the non-diapausing colony along with the improvements to the rearing system will allow researchers to produce up to six generations of the northern corn rootworm per year, which would facilitate research and advance our knowledge of this pest at an accelerated rate.