[5] Similar to other pentatomoids, Cydnidae have glands in the thorax (adults) or the lateral part of the abdomen (nymphs) that secrete a foul-smelling mix of chemicals for defense against predators.

Of the peanut-feeding species, Pangaeus bilineatus is the most abundant and the only one associated with feeding injury to peanut kernels.

[7] Another pest is Fromundus pygmaeus, which attacks rice seedlings, sugarcane, fallen seeds of grasses and roots of soybean and clover.

The aforementioned F. pygmaeus facultatively sucks blood from humans,[8] while Chilocoris assmuthi can cause brown lesions on skin (usually on the feet) with its defensive secretions.

[6] BioLib includes the following subfamilies: In some older classifications, Cydnidae sensu lato includes the subfamily Thyreocorinae (now a separate family, Thyreocoridae), which are known commonly as "negro bugs" or "ebony bugs", and/or the families Thaumastellidae and Parastrachiidae.