Shield bugs are members of the order of insects known as Hemiptera and, as the University of Kentucky Department of Entomology points out, are often referred to as "True Bugs." Shield bugs are also directly related to stink bugs and, like all Hemiptera species, they consume food by piercing and sucking, as opposed to chewing. They may be found throughout the world and it is estimated that, globally, there are 6,500 shield bug species.
Shield bugs, like stink bugs, have a distinctive, triangular-shape plate that is attached to their backs. The plate resembles a shield and, in fact, helps to provide protection. This plate or shield is known scientifically as the "scutellum" and varies in size, depending upon the species. In certain cases, the scutellum may cover the entire body of the shield bug.
The body of the shield bug is divided into three sections: the head, the thorax and the abdomen. The head contains the shield bug's beak or "rostrum," as well as two eyes and two antennae. The thorax, or middle section, contains the legs and wings. The abdomen, or rear section, contains the shield bug's digestive and reproductive systems.
Common to all members of the Hemiptera order is the rostrum, which is the scientific name for the beak that is used to pierce and suck liquid from food sources. Most shield bugs are herbivores, or plant eaters, and will consume the juices of fruits and seeds, as well as sap from plants and nectar from flowers. Some shield bugs, though, are predators and will use their beaks to pierce other insects and then suck out their body fluids. Certain shield bugs feed on both plants and insects.
Shield bugs are generally found in plants and crops, such as beans, cabbage, cotton, melon and squash. Eggs are laid on leaves in clumps of 20 to 30 and are oval or barrel-shaped in appearance. It generally takes one month from the time of hatching for a shield bug baby, or "nymph," to become an adult. Once grown, the shield bug can range in length from approximately 1/4 to 1 inch and, depending upon the species, the colour of a shield bug varies from dull to bright. Some are multicoloured.
Pests or Partners
For farmers, the shield bug can be either a problem or a helper. Shield bugs themselves are not harmful to humans, but those that eat and damage crops can make life difficult for the farmer. Some predator shield bugs, though, are useful to farmers since these shield bugs target and feed on insects that pose an even greater danger to crops.
The "stink" that both shield bugs and stink bugs release when disturbed or crushed is a liquid that is produced and stored in glands that are found in the bug's thorax. The foul smell is meant to serve as a defensive agent, keeping away predators who may want to feast on the shield or stink bug.
Shield Bug Relatives
Some of the many insects that are related to the shield bug are the assassin bug, the bed bug and the water bug.