Lygus spp. is a serious pest of a wide range of plants all over the world with potential to affect their yields significantly. Lygus bugs decreased buckwheat yield by an average of 59% in four separate trials when not controlled by insecticides in late July. Chemical control of late season populations of Lygus bugs resulted in non-significant increase in yield. Giving the undesirable effects of insecticides on human consumed crops like buckwheat, especially late in the season, a trial was conducted to study the effects of the applications of the pyrethroid insecticide Matador^® (cyhalothrin-lambda) early in the season only; and the emulsifiable suspension formula of the mycoinsecticide Botanigrard ES^® (Beauveria bassiana strain GHA) late in the season on Lygus bugs on buckwheat in Winnipeg, Manitoba, Canada. Late season application of B. bassiana resulted in a significantly higher yield than the untreated control. The combination of early insecticide and late mycoinsecticide application resulted in significantly higher yield than the control. The early season application of Matador^® reduced Lygus bugs to very small numbers. However, B. bassiana treatment did not decrease bug numbers, but did result in a significantly higher percentage of infected Lygus adults in fungus-treated plots than in untreated plots. This pattern of infection was sustained for at least 13 days after the application.