Small, Creepy, and Beautiful Predacious Tigers of the Soil

To our knowledge, beetles (Order Coleoptera) are the most diverse group of insects on the planet. In the United States, there are 30,000 described species. Such species diversity comes along with so many morphological, behavioral, and ecological differences. All that means coleopterans display different sizes, food, and habitat preferences. As you may guess, there is plenty of information about beetles (see the suggested reading in this document) so you may be surprised to learn how funky and fascinating some species are.

Among the 155 families of beetles found in the eastern United States, ground beetles (family Carabidae) are considered one of the largest families by species numbers. Carabids are known to be important predators of agricultural pests. Most species are generalist and opportunistic predators, but there are some members of the family that feed on slugs, springtails, or even have omnivorous feeding habits.

Tiger beetles (subfamily Cicindelinae), are ferocious predators during both larvae and adult stages. As the name suggests, adults are equipped with an acute sight and strong mandibles. Moreover, they are fast runners (Figure 1).

Figure 1. Adult specimen of the six-spotted tiger beetle (Cicindela sexguttata) collected in Princeton Kentucky. Adults are 12 – 14 mm length. Picture and ID credits A. Falcon.

If you think some insects can have bizarre appearances, it is time to take a look at the larvae of tiger beetles (Figure 2). Whereas common ground beetle larvae can be found actively looking for prey on debris or plants, tiger beetle larvae make vertical burrows in the soil and wait to capture prey wandering in the ground such as incautious beetles, caterpillars, ants, or anything they can catch. During the scouting of alfalfa fields in the UK Research and Education Center at Princeton, several tiger beetle larvae in their tunnels about 10 inches in depth were found. The larva uses its head to plug the entrance of the tunnel and then waits to attack a prey with its powerful mandibles.

Figure 2. Larva of a tiger beetle found at the UK Research of Education Center at Princeton. The red arrow shows a modified dorsal segment bearing hooks used to move back and forth across the tunnel. Picture credits A. Falcon.

Implications for biological control

Tiger beetles are generalist predators, so they may catch different arthropods including insects and spiders. It is unclear how much they can contribute to the control of pests, but you will find these beetles are active searching and capturing bugs in agricultural fields of Kentucky during spring and summer.

Interesting facts about tiger beetles

  • There are over 100 species of tiger beetles in the Unites States. Cicindela sexguttata (the one show in Figure 1) is a relatively common species across the eastern half, and also southeastern Canada.
  • Depending on the species, the larval stage can last from 2 to 3 years before becoming adults.
  • Larvae can survive flooding conditions.
  • Tiger beetles are known by their astonishing running speed. They can reach 5.5 mph, which would be equivalent to a human running at 720 mph!

Suggested reading

Arnett, R. H. 1968. The Beetles of the United States (A Manual for Identification). American Entomological Institute, Ann Arbor, Michigan.

Dillon, E. S. & Dillon, L. S. 1961. A Manual of Common Beetles of Eastern North America. Row, Peterson and Co., Evanston, Illinois.

Downie, R. H. & Arnett, R. H. 1996. The Beetles of Northeastern North America, Volumes 1 and 2. Sandhill Crane Press, Gainesville, Florida.

White, R. E. 1983. A Field Guide to the Beetles of North America. Houghton Mifflin, Boston.

Tiger beetles, in Kentucky Critter Files

By Armando Falcon-Brindis, Research Analyst; and Raul T. Villanueva, Entomology Extension Specialist

Posted in Beneficial Insects
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