Many retail nurseries and garden centers sell lady beetles for controlling aphids in gardens and landscapes. Gardeners often ask, “Does releasing lady beetles really work?”

Lady beetles sold at nurseries for aphid control are convergent lady beetles, named for the converging white marks on its thorax. Suppliers collect beetles from large overwintering aggregations in California's foothills and mountains. Many other species of lady beetles occur naturally in California landscapes but don't aggregate in the mountains and aren't sold commercially.

University of California research has demonstrated that lady beetle releases can effectively control aphids in a limited landscape or garden area if properly handled...

Oils are some of the most useful pesticides available for managing pests on woody ornamentals and fruit trees. They are also widely used on many herbaceous flowers and vegetables. Oils control a range of soft-bodied insects and mites, as well as several foliar diseases including powdery mildew (Table 1). Not only do oils leave no toxic residues, they are safe to use around people, pets, and wildlife; have low impact on beneficial insects; and won't harm honey bees unless applied directly to flowers during the time of day that bees are foraging.

Oils used for managing pests on plants are most often called horticultural oils. Horticultural oils are derived from petroleum sources, and are sometimes called...