Veronica Yurchak, Vegetable Specialist, UMD; vjohnso4@umd.edu
Figure 1. (Left) Coccinella septempunctata adult (Right) Coleomegilla maculata adult.
Ladybird beetles (Family: Coccinellidae), also commonly known as “ladybugs” or “lady beetles” are a familiar beneficial insect found in most crop fields and home gardens. There are many species of ladybugs in the Delmarva region, and both the adult and larval stages of nearly all species are predatory. Their prey includes a variety of small, soft-bodied insects including aphids, thrips, scale insects, whiteflies, small caterpillars, and insect eggs. One common ladybug species, the convergent ladybug can consume up to 50 aphids per day as an adult. Another species, the sevenspotted ladybug, can consume hundreds of aphids per day as an adult. While each species of ladybug has preferences for what pests they will eat, in general, most tend to have a broad host range and feed on any small arthropods or insect eggs they can successfully attack and ingest. One notable exception is a group of black ladybugs, commonly called spider mite destroyers, which specialize on spider mites and are sold commercially as biocontrol agents specifically for this pest.
Figure 2. Ladybug pupa on sweet corn leaf.
Figure 3. Ladybug larva (Coccinella septempunctata)
Ladybugs have a lifecycle similar to that of a butterfly, with four distinct stages depending on the age of the insect. Being able to identify all life stages can help you recognize and protect these beneficial insects. The adult stage is the most easily recognized with domed, hard, round or oval bodies. Depending on the species, ladybugs can be red, pink, black, yellow, or orange with varying numbers of spots (Figure 1). Also, like butterflies, the pupal and larval stages of ladybugs do not at all resemble the adult stage. Pupae are typically orange to red with a shriveled appearance, and can often be found anchored to the upper side of plant leaves (Figure 2). Larvae have long, tapered bodies that are typically black with areas of white, orange, or red (Figure 3). Some species also appear to have bumps or spines along their bodies. This stage lasts 2-3 weeks, depending on temperature, and consumes more pests than the adult stage. The oval-shaped eggs are orange, yellow, or red, and laid in clusters of 5 to 30 eggs (Figure 4).
Figure 4. Ladybug eggs.
While ladybugs are overwhelmingly considered beneficial in field and garden settings, one of the most common ladybug species, the multicolored Asian lady beetle, is a nuisance pest in the fall when it enters homes and buildings, often in large numbers, looking for an overwintering site. Despite this, these ladybugs are still beneficial predators that should be controlled only when trying to enter buildings in the fall. Another beetle species in the same insect family is the Mexican bean beetle, a common pest of legumes that feeds exclusively on plant tissue. Except for Mexican bean beetles and squash beetles (a relatively uncommon pest of cucurbits) all Coccinellidae in the Delmarva region are predatory. During times of low prey availability, however, most adult beetles will also feed on nectar and pollen. As a result, they can be attracted to sites by including a variety of flowering plants in small-scale plantings or unmanaged field margins around larger production fields. Keep an eye out for this diverse group of predators this season!