Grasshoppers and their Relatives 550 species in 94 genera have been described, mostly from arid regions of Asia and Africa, with a few representatives in southern Europe Sexual dimorphism is often marked, with males in general being significantly smaller and often fully winged, as opposed to completely wingless females The surface of the body is frequently rough and uneven, and many species blend superbly among rocks and pebbles Some South African species (Trachypetrella) have been dubbed ‘‘living rocks.’’ Defensive stridulation is common in both nymphs and adults of many species, and it is achieved by various mechanisms (often more than one stridulatory mechanism is found in a single species) The typical advertisement stridulation is rare but, if present, the sound produced by males by rubbing their hind legs against the tegmina is exceptionally loud (Lobosceliana) Romaleidae (Lubber Grasshoppers) This family includes nearly 500 species in more than 100 genera, distributed mostly in warmer regions of North and South America Romaleidae are large grasshoppers, usually strikingly colored Species of Tropidacris and Titanacris are some of the largest orthopterans, with wingspan reaching 250 mm The pronotum in the members of this family is often strongly keeled or crested Wings, if present, have dense venation, and the hindwings often have a unique stridulatory mechanism formed by numerous fine teeth on one of the veins Sound is produced by rubbing this vein against the underside of the tegmen In addition to stridulation, some species produce a hissing sound by expelling air through their thoracic spiracles Lubber grasshoppers have little economic significance, although a few species can defoliate trees on tropical plantations In the USA, the best-known representative of this group is the Florida Lubber Grasshopper (Romalea microptera), a large and colorful grasshopper frequently used to study insect internal anatomy and external morphology Acrididae (True Grasshoppers and Locusts) This is the largest family of Acridoidea, with nearly 6500 species in more than 1420 genera and 25 subfamilies They occur in all regions of the world, and in nearly all terrestrial and semiaquatic habitats Their body size ranges from less than mm to approximately 100 mm Body form and shape are varied, from robust and stocky to exceptionally slender and elongate Wings can be fully developed, reduced, or entirely absent Wing polymorphism is common in some groups (Gomphocerinae) Abdominal tympanal organs are generally present, absent only in some wingless forms Many species stridulate by rubbing their hind femora against modified veins on the tegmina Sometimes, an expanded area on the tegmen forms a membranous ‘‘speculum,’’ which acts as a resonator All species of locusts and most other economically important grasshoppers belong to this family Also, most grasshoppers common in temperate zones of the world belong here, and nearly the entire grasshopper fauna of Australia is the result of a massive adaptive radiation within one of the lineages of this family (Catantopinae) Members of the small subfamily Paulininae are unique among other grasshoppers in 735 their nearly fully aquatic lifestyle They are capable of skating on the surface of the water, diving, and swimming, and their eggs are laid on stems of submerged aquatic plants The hind tibiae are flattened and widened at their apices, forming effective swimming paddles Only two genera with five species belong to this family, and their original distribution was restricted to South America Recently, one species (Paulinia acuminata) has been deliberately introduced to Africa in an effort to control the noxious aquatic plant Salvinia This is probably the only example thus far of a truly beneficial species of grasshopper Pyrgomorphoidea (Gaudy Grasshoppers) Approximately 470 species are known in this family, placed in more than 150 genera They are distributed mostly in the tropics of the Old World, with only a few species known from Mexico and Central American countries The body is usually large, often reaching 90 mm The pronotum is quite variable in form, sometimes adorned with granules or spine-like processes Pyrgomorphidae not use sound in their courtship behavior, but some make rustling noises with their wings when alarmed Many members of this family have warning (aposematic) coloration, a characteristic frequently associated with their toxic properties (Figure 10) Some species eject protective froth or irritating fluids as a defense mechanisms, and quite a few species are poisonous Some species are gregarious, especially during their early nymphal stages A few have been known to cause serious damage to crops in Africa (Zonocerus) Trigonopterygoidea (Leaf Grasshoppers and Wingless Desert Grasshoppers) This small group of grasshoppers includes only 21 species and seven genera, divided into families Trigonopterygidae (leaf grasshoppers) from southeast Asia and Australia and Xyronotidae from southwestern North America (desert wingless grasshoppers) Leaf grasshoppers are associated with humid, dense forests, and in their morphology resemble dry, brown Figure 10 Pyrgomorophoidea: Gaudy grasshopper Zonocerus elegans from South Africa