EXPLORE # 21 SHIELD BUG ~ Pentatomoidea is a superfamily of insects in the Heteroptera suborder of the Hemiptera order, which are commonly referred to as shield bugs or stink bugs. Shield bugs have glands in their thorax between the first and second pair of legs which produce a foul smelling liquid. This liquid is used defensively to deter potential predators and is sometimes released when the bugs are handled carelessly. The distinctive smell comes from aldehydes such as CH3–(CH2)2–CH=CH–CHO, and is chemically similar to pheromones. The nymphs, similar to adults except smaller and without wings, also have stink glands. The nymphs and adults have piercing mouthparts which most use to suck sap from plants, although some eat other insects. When they group in large numbers they can become significant pests. Shield bugs come in many colors.