By Alecia Alexander, IPM Intern
(see below for photos of the life stages)
Lady beetles, also known as ladybugs or ladybirds, are beneficial predators of plant pests. The eggs of lady beetles are usually yellowish in color and elongated in shape. They can be laid in small clusters on the underside of leaves hidden from flying predators and protected from the weather. However, lady beetles will lay eggs on any surface near insect prey. Lady beetles try to lay their eggs on plants that are infested with aphids or other plant-eating insects so the newly hatched larvae will have prey to feed on. Many scientists believe that lady beetles lay infertile and fertile eggs when infested plants of plant-eating insects are in short supply. By doing this the hatched larvae will be able to feed on the infertile eggs and have a better chance of survival.
The larva of a lady beetle in most species is dark gray/ black with brightly colored bands or spots. Their bodies are elongated and slightly pointed at the rear with prominent legs that stick far out the side of the body. The lady beetle larva feeds voraciously on soft-bodied plant pests such as aphids, mites, and insect eggs. When ready to pupate the lady beetle larva will attach itself to a surface. They begin to shrink in form and remain motionless. The pupa is usually dark orange/red and often has spots.
When the lady beetle emerges from the pupal skin it is vulnerable to predators. Newly emerged adults have a soft exoskeleton and are pale/yellow in color. After a day or two the wing covers will harden and their color darkens. There are many species of lady beetles. Most have an oval like shape to them and can be yellow, pink, orange, black, or red. They usually have distinct spots but can also have none or stripes. They discourage other animals that may eat them with their warning coloration. Adult lady beetles feed on aphids and other soft bodied insects like the larvae. Over the lifetime, one lady beetle can eat as many as 5,000 aphids. When food is scarce they will consume newly molted lady beetles or eggs of lady beetles. There are some species of lady beetles (family Coccinellidae) that are pests and feed on plants rather than insects, such as the Mexican bean beetle.