Phymateus is a genus of fairly large grasshoppers of the family Pyrgomorphidae, native to shrubland, semi-deserts, savanna, woodland, gardens and cultivated areas in Sub-Saharan Africa, with ten species in the African mainland and two species in Madagascar.

[2][3] Phymateus are African grasshoppers that typically are about 4–8.5 cm (1.6–3.3 in) long as adults, with females generally being larger than males of the same species.

[4] Their toxins, which are accumulated from the toxic plants they feed on, can be very strong and there have been reported deaths in birds and mammals, including humans, after eating Phymateus grasshoppers.

[2][6] They may congregate in large numbers on trees and shrubs, in some species arranged in such a way as to resemble foliage.

Although adults of both sexes are fully winged, in at least P. morbillosus the females, which are longer and considerably heavier than males, are unable to fly.