Insects are not only the largest arthropod group, but also the most diverse. Unlike other arthropods, insects always have three pair of legs and one pair of antennae. Common insects found in the grasslands include moths and butterflies, such as the common branded skipper, the Baird's swallowtail, the hummingbird clearwing and the Aphrodite fritillary; beetles, such as tiger beetles and the red milkweed beetle; as well as several species of grasshoppers, flies, wasps, bees, ants, aphids and dragonflies.
Arachnids are a class of arthropods that include spiders and scorpions. Unlike insects, arachnids have four pairs of legs and do not have antennae. Species living in grasslands include the Northern scorpion (Paruroctonus boreus), the desert grassland scorpion (Paruroctonus utahensis), the green lynx spider (Peucetia viridans), the brown recluse spider (Loxosceles reclusa), the black and yellow garden spider (Argiope), tarantulas (family Theraphosidae), jumping spiders (family Salticidae), comb-footed spiders (Theridiidae), funnel-web spiders (Agelenidae) and wolf spiders (Lycosidae).
Chilopods include all centipede species while Diplopoda refers to the arthropods called millipedes. Although centipedes and millipedes have long bodies and several pairs of legs, these two groups are distinct. Some centipedes are venomous and have from less than 20 to 177 pairs of legs while millipedes can have as many as 200 pairs of legs. Species living in the grasslands include members of the genera Scolopendra, Oxidus and Julus.
Entognatha is a class of arthropods that includes springtails, diplurans and proturans. These elusive arthropods live in or near the soil of many biomes, including grasslands. Springtails, diplurans and proturans are small, rarely measuring more than 0.2 inch. Unlike insects, these arthropods have their mouthpieces enclosed inside their heads. They feed on living and decaying plant material. Tomocerus minor is a springtail widespread in the grasslands.