Actually, we should call them Lady Beetles, as they are a true beetle with hardened protective wings (Coleopteran) Our native Lady Beetle, with nine spots (Hippodamia convergens), are so named because of their tendency to converge in swarms from time to time. You may be lucky enough to see one of these gatherings: a seemingly random mountain shrub, such as a coyote bush, completely covered with 100s of red Lady
beetles.
Chiricahua Mountains in SE Arizona. Frank Baker.
Lady beetles are great friends to gardeners because of their voracious appetite for aphids. BUT their life cycle is often migratory---wintering in higher altitudes and returning to gardens and agricultural valleys in warmer weather. Their tendency to roam makes those advertisements for shipments of lady beetles misleading. Sounds good on paper, but don’t fall for it. Once released in your garden, they are likely to move on to higher or lower climes, depending on the season. The commercial gathering of lady beetles is discouraged. Not only will they not stick around after purchase, but harvesting disrupts their life cycle.