The life cycle of a shield bug

Shield bugs live all over the world. They are called shield bugs because the shape of their bodies resembles that of a shield. There are 180 different species of shield bugs worldwide that belong to the family Acanthosomatidae. Shield bugs are also sometimes called parent bugs or stink bugs.

Shield Bug Early Life

Shield bugs start out as eggs. The shield bug mother will generally lay around 100 eggs in the spring. Depending on the species, the eggs will need about a month to hatch. Shield bugs do not have a larval stage. Instead, they hatch as nymphs, smaller versions of the adult shield bugs they will become. Shield bugs will moult five times before reaching their adult size. Each of these moults will reveal a different colour pattern and a little bit larger insect.


The shield bug will reach adulthood in the early fall. Shield bugs come in a variety colours, but they usually blend in with their surroundings. Most shield bugs eat leaves and plant sap. Some shield bugs eat smaller insects. Shield bugs have a unique digestion process. They need a specific bacteria to help them break down their food. In order to ensure that the young have this bacteria, the mother secretes some of her own bacteria on the eggs. When the young shield bug hatches. the first thing it does is eat its own egg casing. This gives the newborn shield bug enough bacteria to digest its first meal and gives the bacteria a chance to thrive in the gut of the new baby.

Seasons Change

By late fall, the adult will change colour to better blend in with the winter foliage. They will hibernate in sheltered areas near the plants they eat. In early spring, the adults will awaken from hibernation and look for mates. Like many other insects, shield bugs mate facing opposite directions. Depending on the species, the mother will need a week or two after conception before she is ready to lay her eggs, starting a new cycle of life.

Parent Bugs

Unlike most insects that lay eggs and leave, shield bug mothers are very good parents. In some species the mother will stay with her eggs as they gestate and protect the newborns. By the time they are 10 days old, the young shield bugs will follow their mother wherever she goes. According to Earthnet, this behaviour has been recorded as early as 1764.


Some shield bugs create a noxious secretion from the bark and leaves they eat. They basically barf this fluid up to defend themselves from predators. This is why they are commonly known as stink bugs. While this secretion isn't harmful to humans, it can colour skin or clothing and it does smell. Washing with soap and water will remove the odour but not always the stain.

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About the Author

Based in Nashville, Shellie Braeuner has been writing articles since 1986 on topics including child rearing, entertainment, politics and home improvement. Her work has appeared in "The Tennessean" and "Borderlines" as well as a book from Simon & Schuster. Braeuner holds a Master of Education in developmental counseling from Vanderbilt University.