- named after an insectoid (or arachnoid) animal
- relatively small (usually in the light weight class)
- fast-moving and mobile
- relatively weak individually
- relatively cheap
- easy to acquire and maintain, to the point of being considered an ubiquitous design
There seems to be an informal convention to give "Bug" names to 'Mechs that fulfill (most of) the latter five characteristics, and indeed many typical Bug 'Mechs do not exceed 20 tons which is the lower end of the light spectrum (with 'Mechs below 20 tons being classed as ultralight instead, such as the 15-ton FLE-14 variant of the Flea). The only notable outliers are the 55-ton Scorpion and the 70-ton Grasshopper.
Named Bug 'Mechs
'Mechs that arguably qualify as Bug 'Mechs but apparently have not explicitly been referred to as such include the light Firebee (35 tons), Mantis (30 tons), Scarabus (30 tons), and Super Wasp (25 tons), and the low-end medium-class Cicada (40 tons).
The Grasshopper, a heavy and powerful 70-ton 'Mech, would only qualify based on its name, and is not normally considered part of the Bug 'Mech group.
- The Insect Brigade mercenary unit was apparently named in reference to the Bug 'Mech concept, and they were noted to be particularly skilled pilots of Bug 'Mechs.
- Brush Wars, p. 142 (Insect Brigade special abilities: Named Bug 'Mechs are the Locust, Stinger, Wasp, and Scorpion)