These colorful, insects appear each winter by the hundreds of thousands on Mt. Diablo. Guided by some inner map, they mass in the same sheltered ravines year after year, dispersing in the spring to search for food. However winsome they may seem to humans, ladybugs are rapacious armored tanks to their favorite prey, aphids. Because of the beneficial role they played in medieval Europe by ridding gardens and vineyards of aphids, they were reverentially dubbed “Our Lady” beetles, after the Virgin Mary; hence the derivation ladybug (“ladybird” in Britain). Look for swarms of adult ladybugs in dark, shaded ravines, especially on the Falls Trail.