As the names imply, milkweed bugs feed on milkweed and may feed occasionally on other forage or herbaceous plants. Boxelder bugs feed primarily on boxelder. There are usually two generations of these insects per year. In the fall adult and late instar nymphs migrate in search of places to spend the winter. They often congregate in large numbers in homes and other buildings where they will hide in cracks and crevices. During the winter on warm days, they may come out of hiding and sun themselves on building walls. In the spring they will disperse into the fields and trees from where they came. Adults will lay eggs on preferred host plants where nymphs will feed, and the life cycle begins again.
Both milkweed bugs and boxelder bugs cause little if any damage to landscape and garden plants other than milkweed and boxelder. Thus control is seldom necessary. Boxelder bugs feed only on boxelder and primarily on female or pod pearing boxelder. Therefore, avoid planting a female boxelder in your landscape or remove the one you already have. Also both these insects can be easily controlled with an insecticide.