Ebony bugs are members of the order of true bugs, but they look a lot like tiny, shiny black beetles. Upon first glance, you might even think they are glossy, round seeds. They’re often found in groups. Their bodies are fat, almost spherical ovals. They’re almost always seen on flower clusters and immature seeds, often on members of the carrot or parsley family.
The family as a whole is distinguished from similar insects by the overall body shape and size, by the antennae (which have 5 segments), by the strawlike beak (which has 4 segments), and by the tibias (shinlike portions of the legs), which either lack spines or only have thin spines. In adults, the scutellum is large enough to cover most of the abdomen and the wings (in true bugs, the scutellum is a plate, often triangular, that is attached at the rear part of the pronotum, which is the shoulderlike plate just behind the head). Most ebony bugs are shiny, but some are not.
The dozens of species in the ebony bug family can be tricky to tell apart, mainly because they’re so small. North American ebony bugs are in three genera: Corimelaena, Cydnoides, and Galgupha.
Similar species: Ebony bugs, with their shiny, shell-like scutellum covering their abdomen, resemble beetles — especially the tiny, black, rounded beetles in family Histeridae, often called clown beetles or hister beetles. But note that in beetles, the protective “shells” are a pair of modified forewings (elytra) that meet in a straight line down the back.
Note that there are some relatives of ebony bugs that are also tiny, rounded, and black or blackish. Examples include certain species of burrowing bugs (family Cydnidae), shield-backed bugs (family Scutelleridae), and stink bugs (family Pentatomidae).
Adult length: less than ¼ inch; many only about ⅛ inch.
Habitat and Conservation
Most commonly noticed in open, grassy areas such as pastures, old fields, roadsides, prairies, wetlands, and similar habitats. Ebony bugs are usually seen as they feed on the flowers and developing seeds of their food plants — typically, wildflowers that hold their flower clusters a few feet above the ground. Look for them, especially, visiting the flowers of Queen Anne’s lace and other members of the parsley or carrot family. When you see them, they often occur in the dozens.
Like others in the order of true bugs, ebony bugs have strawlike mouthparts that they jab into their food source and then use to suck out nutritious juices. In the case of ebony bugs, they usually feed on flowers and developing seeds. Many are especially associated with members of the carrot or parsley family (Apiaceae), so look for them on Queen Anne’s lace, rattlesnake master, fennel, dill, wild parsnip, and others.
Like most other members of the true bug order, ebony bugs undergo a rather simple progression from egg through a number of wingless, immature stages (called nymphs) before a final molt brings them to the sexually mature, winged adult stage. They probably overwinter in the adult stage.
Little information seems to be available about the effect ebony bugs have on crop or landscaping plants. Apparently, their impact is rather mild.
In some older references, you might find this family of bugs called the Cormelaenidae, but that name was proposed some 30 years after a scientist had already described the family using the name Thyreocoridae, and according to scientific naming conventions, a preexisting name is always used.
The family name, Thyreocoridae, includes the roots thyreo (a shield) and corid (a true bug), and it translates to “shield bug.” It refers to the enlarged scutellum that covers the whole abdomen of adults. By the way, the family name of the related shield-backed bugs, Scutellaridae, similarly refers to the prominent scutellum in that group.
In older references, you might find ebony bugs called “negro bugs”; although that term might originally have referred simply to the color black, thoughtful naturalists have turned to a less freighted term for the common name for these insects.
Ebony bugs are just some of the thousands of insects that make their living from the many flowers and seeds that form in prairies, pastures, roadsides, wetlands, and other places where their food plants thrive. To some extent, they must reduce the seed production of their food plants, but considering the abundance of seeds, and in many cases, abundance of plants (think of hundreds of Queen Anne’s lace plants growing along a roadside) their impact must not be drastic.
Meanwhile, ebony bugs are no doubt a good source of protein for the many kinds of birds that visit flowerheads for seeds and other foods, and they must be eaten by a wide variety of predatory insects, too.