Tiger beetles are a family of beetles, Cicindelidae, known for their aggressive predatory habits and running speed. The fastest known species of tiger beetle, Rivacindela hudsoni, can run at a speed of 9 km/h (5.6 mph; 2.5 m/s), or about 125 body lengths per second.[2] As of 2005, about 2,600 species and subspecies were known, with the richest diversity in the Oriental (Indo-Malayan) region, followed by the Neotropics.[3] While historically treated as a subfamily of ground beetles (Carabidae) under the name Cicindelinae, several studies since 2020 indicated that they should be treated as a family, the Cicindelidae, which are a sister group to Carabidae within the Adephaga.[4]
Tiger beetles often have large bulging eyes, long, slender legs and large curved mandibles. All are predatory, both as adults and as larvae. The genus Cicindela has a cosmopolitan distribution. Other well-known genera include Tetracha, Omus, Amblycheila and Manticora. While members of the genus Cicindela are usually diurnal and may be out on the hottest days, Tetracha, Omus, Amblycheila and Manticora are all nocturnal. Both Cicindela and Tetracha are often brightly colored, while the other genera mentioned are usually uniform black in color. Tiger beetles in the genus Manticora are the largest in size of the family. These live primarily in the dry regions of southern Africa.[5]
The larvae of tiger beetles live in cylindrical burrows as much as a meter deep. They are large-headed, hump-backed grubs and use their humpbacks to flip backwards, for the purpose of capturing prey insects that wander over the ground. The fast-moving adults run down their prey and are extremely fast on the wing, their reaction times being of the same order as that of common houseflies. Some tiger beetles in the tropics are arboreal, but most run on the surface of the ground. They live along sea and lake shores, on sand dunes, around playa lakebeds and on clay banks or woodland paths, being particularly fond of sandy surfaces.[6]
Tiger beetles are considered a good indicator species and have been used in ecological studies on biodiversity. Several species of wingless parasitic wasps in the genus Methocha (family Thynnidae), lay their eggs on larvae of various Cicindela spp., such as Cicindela dorsalis.[7]
Tiger beetles display an unusual form of pursuit in which they alternatively sprint quickly toward their prey, then stop and visually reorient. This may be because while running, the beetle is moving too fast for its visual system to accurately process images.[2] To avoid obstacles while running they hold their antennae rigidly and directly in front of them to mechanically sense their environment.[8] There are many tiger beetles that hunt in flat, sandy areas, and their eyes have flat-world adaptations, such as high-acuity perception streaks corresponding to the horizon. A tiger beetle uses the elevation of its potential prey in its visual field to determine how far away it is. As visual hunters, tiger beetles tend to hunt in open, relatively flat habitats, such as sand bars, woodland paths, and barren ground scrubland. In this sense, beetles might be expected to use elevation as a distance cue in their visual pursuit of prey. [9]