Insects in the subfamily Phymatinae are commonly called ambush bugs after their habit of lying in wait for prey, relying on their superb camouflage. Armed with raptorial forelegs, ambush bugs routinely capture prey ten or more times their own size. They form a subgroup within the assassin bugs.
Phymatinae are long. The most distinguishable trait of this group is the presence of pronounced raptorial forelegs. In Phymata, the scutellum is triangular and shorter than the pronotum. In Macrocephalus, the scutellum is narrow and rounded, extending to the tip of the abdomen.
Phymatinae normally have a large fore femur and clubbed antennae. The forewing membranes sometimes lack distinct cells.
The antennae have four segments. There are two ocelli. The beak has three segments. The tarsi also have three segments. The rear half of the abdomen expands beyond the edges of the wings.
Compared to classic assassin bugs, ambush bugs are shorter, stouter, more colorful, an