Tiger Beetles of the United States
Introduction
Tiger Beetles
About 2000 species of tiger beetles (Coleoptera: Cicindelidae) occur worldwide and over 100 are found in North America. Most are restricted to environments with access to open substrate including stream edges, saline flats, seashores, and sand dunes. Although mostly small in size, tiger beetles are important predators of the insect world. Their beauty, diversity, and wariness make them a favorite among collectors worldwide. Besides their appeal to collectors, researchers find tiger beetles are excellent models to study community ecology, biology, morphology, thermoregulation, predator-prey interactions, biogeography, and physiology. These characteristics make tiger beetles one of the best studied non-pest insects and have resulted in having the scientific journal, Cicindela, dedicated to their biology.
Tiger beetles are important components of the ecosystem. They are an important link in the food chain. Tiger beetles are preyed upon by a variety of invertebrates, including spiders, robber flies, and dragonflies, and vertebrates including toads and lizards. As larvae, they are attacked by bee fly parasites and several types of wasps. Tiger beetles are also easily studied bio-indicators of environmental quality. The presence or absence of certain species can provide information on the quality of the habitat, successional stage of the habitat, and/or alterations to the habitat. Because of their restricted habitat requirements, tiger beetles are susceptible to environmental degradation and several species and subspecies are state or federally-protected.
Adults
Adult tiger beetles are mostly day-active predators occurring on open substrates where they forage on small arthropods. These adults are well-known for their quick running and agile flying abilities. Many species are brilliantly colored while others are camouflaged, blending in with their habitat. About three-fourths of the tiger beetles in North America belong to the genus Cicindela. Species are distinguished by differences in size, coloration, and markings on their wing covers.
Tiger beetles are dependant on the environment for their body temperature, but they regulate body temperatures within a narrow range by behavioral mechanisms, including basking and stilting (holding their body above the substrate), seeking favorable microclimates including damp or shaded areas, and digging burrows.
Tiger beetles are efficient visual predators that prey upon a wide variety of arthropods including insects, spiders, and small terrestrial crustaceans. In addition to feeding, adult tiger beetles are responsible for reproduction. Adult males exhibit a behavior known as mate-guarding. The male holds onto a female using his large jaws and protects her from other males.
Larvae
Tiger beetle larvae typically occur in the same location as adults. The adult female selects an oviposition site, excavates a small hole up to 1 cm deep, deposits a single egg, then covers the hole. Females are extremely specific in choosing oviposition sites and appear to favor damp soil. After hatching, the larva digs a cylindrical burrow at the site of oviposition. There are three instars, and the larva enlarges and deepens the burrow as it grows. Larval development is dependent on climate and food availability and typically requires 2-3 years for completion. The prolonged and sedentary life cycle exposes the larvae to environmental stresses including flooding and drought.
In addition to climatic stresses, tiger beetle larvae may also be subjected to food limitation and starvation. The larvae are ambush predators that wait at the top of their burrows for prey to approach within striking distance. When food-limited, larval tiger beetles have longer development times and emerge as smaller and less reproductively-able adults.
About This Site
This site was developed to provide easily-accessible information about the county-level distribution of all tiger beetle species in continental North America. Although numerous subspecies and tiger beetle races have been named and described, we have limited this site to species. Characteristic specimens of each species have been photographed from the dorsal and lateral view. However, considerable variation in adult color and elytral markings exist.
We created this site based on published literature of tiger beetle occurrences. The popularity of the group is underscored by the existence of checklists and complete occurrence records of tiger beetles in 32 U.S. states. Only one U.S. state, Wisconsin, lacks any published information and several other states including California, Montana, Illinois, Kentucky, Missouri, Massachusetts, Tennessee, and Wyoming have very little published data.
