Tiger beetles or theCicindelidae are a family ofbeetles 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 ofground beetles (Carabidae) under the name Cicindelinae, several studies since 2020 indicated that they should be treated as a family, the Cicindelidae, a sister group to Carabidae, within theAdephaga.[4]
Many tiger beetles have large bulging eyes, long slender legs and large curvedmandibles. BothCicindela andTetracha are often brightly colored, while the other genera mentioned are usually uniform black in color. Tiger beetles in the genusManticora, which live primarily in the dry regions ofsouthern Africa, are the largest in size.[5]
While members of the genusCicindela are usuallydiurnal and may be out on the hottest days,Tetracha,Omus,Amblycheila andManticora are allnocturnal. All tiger beetles are predatory, both as adults and aslarvae. They prey on nearly anything they can catch, including other beetles, hoppers,ants andcaterpillars.[2]
The larvae of tiger beetles live in cylindrical burrows as much as a meter deep. The grubs have a large head with a pair of formidable mandibles. They have six simple eyes (stemmata) on each side of the head. Two pairs are much larger than the others, and seem to be used for range estimation. The largest have about 5000 retinal cells.[6] There is a prominent hump on the top of their fifth abdominal segment with two pairs of reverse pointing hooks to anchor them in their burrow with their head filling the entrance and flush with the surface.
Tiger beetle larva repairing its shaft
The larvae wait for prey to come close enough, attempt to grab and pull them down their shaft. The hump and hooks prevent struggling prey from pulling them out of their shaft.
Tiger beetle larvae attempting to catch prey
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 commonhouseflies. 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.[7]
Tiger beetles have an unusual form of pursuit in which they alternately sprint toward their prey, then stop and visually reorient. This may be because the beetle runs 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.[11] Many tiger beetles 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.[12] A few species ofCicindela are able to hunt without using their eyes and several arecrepuscular.[13]
Several species are known to be sensitive to ultrasound and produce ultrasound in response to bats, and are thought to beBatesian mimics, imitating the sounds of toxic moths that are avoided by bats.[14]
The oldest fossil tiger beetle yet found,Cretotetracha grandis, comes from theYixian Formation inInner Mongolia, China, and dates to the earlyCretaceous Period, 125 million years ago. Most fossils found are grey or yellow silty mudstone.[15] Traits that identifyCretotetracha as Cicindelinae include long mandibles shaped like sickles, simple teeth arranged along the mandible's inner surface, antennae that attach to the head between the base of the mandibles and the eye. The left mandible is approximately 3.3 mm and the right mandible is approximately 4.2 mm long. A long body form roughly around 8.1 mm where the combined eyes and head are wider than the thorax, and long running legs.[15] Previously knownMesozoic fossils of tiger beetles have been described from theCrato Formation, about 113 million years ago[15] andOxycheilopsis cretacicus from theSantana Formation, 112 million years ago,[16] both in Brazil.
Tiger beetles had been treated either as a familyCicindelidae or as the subfamilyCicindelinae[17] of theCarabidae (ground beetles) but since 2020, there has been growing evidence for the treatment as a separate family, that is sister to the Carabidae.[4] Many genera are the result of the splitting of the large genusCicindela, and many were described by the German entomologistWalther Horn.[4][18][1]
^Pearson, David L. (2001).Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids. Ithaca: Comstock Publishing Associates. p. 261.ISBN0801438829.
^Layne, J. E., Chen, P. W., & Gilbert, C. (2006). "The role of target elevation in prey selection by tiger beetles (Carabidae: Cicindela spp.)".Journal of Experimental Biology, 209 (Pt 21), 4295–4303.
Acorn, John (2001).Tiger Beetles of Alberta: Killers on the Clay, Stalkers on the Sand. University of Alberta Press.
Pearson, David L.; Cassola, F. (June 2005). "A Quantitative Analysis of Species Descriptions of Tiger Beetles (Coleoptera Cicindelidae), from 1758 to 2004, and Notes about Related Developments in Biodiversity Studies".The Coleopterists Bulletin. 59 (2).
Pearson, David L.; Knisley, C. Barry; Kazilek, Charles J. (2005).A Field Guide to the Tiger Beetles of the United States and Canada. Oxford University Press.
Pearson, David L.; Vogler, Alfried P. (2001).Tiger Beetles: The Evolution, Ecology, and Diversity of the Cicindelids. Cornell University Press.
Schüle, Peter (2010). "Further new country records of African Tiger Beetles with some taxonomical note (Coleoptera, Cicindelidae)".Entomologia Africana 15 (2).
