Basis for Listing
The splendid tiger beetle was first observed in Minnesota in 1954 in Houston County. It is also known historically from Fillmore, Winona, and Wabasha counties. Recently, it has only been collected from the Whitewater Wildlife Management Area in Winona County. The splendid tiger beetle reaches the northern edge of its range in southeast Minnesota and adjacent Wisconsin. It can be very abundant where found, but survey work is incomplete in Minnesota. It was listed as a special concern species in Minnesota in 1996.
Adult splendid tiger beetles are 12-15 mm (0.47-0.59 in.) long, and have dark red wing covers contrasting with a bright metallic green head and thorax. No other tiger beetle in Minnesota resembles it.
Tiger beetle larvae are mostly white and somewhat grub-like (Pearson et al. 2006). The portions of their bodies that are exposed in their burrow entrances are usually the same color and texture as the surrounding soil surface, allowing them to blend in with the soil (Pearson et al. 2006; R. Dana, Minnesota DNR, pers. comm.). Tiger beetle larvae have eyes with dense photoreceptors that give them detailed focusing ability and three-dimensional visual perception (Pearson et al. 2006).
In Minnesota, the splendid tiger beetle prefers steep clay embankments. Thus far it has only been documented in the southeastern forested corner of the state, but in states further south and west it is known to occur in clay soils on the prairie.
Biology / Life History
Adult splendid tiger beetles emerge in the fall (as early as late August), begin hunting until colder weather, and then burrow underground for the winter. They re-emerge in early spring, begin mating and laying eggs, and then slowly die-off as summer progresses.
Tiger beetles prey on small insects and other arthropods and are visual hunters. Adults will either chase their prey or wait in a shaded area and ambush prey as it wanders by (Pearson et al. 2006). They often chase their prey in fast, short bursts with brief stops in between runs. These stops are necessary for orientation as tiger beetles can run so fast that they cannot see the prey they are pursuing.
Adults have hind wings that are transparent and they are folded under the elytra (hard front wings) when at rest. When disturbed, tiger beetles may take short, low flights to escape. These escape flights and the ability to run quickly are their main defenses against predators. Tiger beetles are also usually well camouflaged in their environment.
Tiger beetle larvae dig burrows in which they live and secure prey. They are ambush predators that lie in wait in the top of their burrows with their jaws open and their heads and thorax flush with the ground surface, essentially filling the burrow entrance and disguising their presence (Pearson et al. 2006). When prey is within reach, the larvae anchor themselves to the sides of the burrow by 2 pairs of hooks on their lower backs, and quickly leap out and grab the prey with their mandibles. The struggling prey is then pulled back into the bottom of the burrow and eaten. When they are done eating, the larvae carry the indigestible portions of the prey to the top of their burrow and throw it backwards away from the burrow entrance. The larvae also use their burrow for protection, and will retreat into it when they sense danger. Larvae primarily use vision to detect danger, but may also sense vibrations in the ground created by large predators (Pearson et al. 2006). It is not known how deep the larvae burrow to overwinter.
Conservation / Management
The splendid tiger beetle occurs in a habitat type that is not generally threatened, but it is very restricted in its range as currently understood.
Conservation Efforts in Minnesota
Additional survey work is needed to determine the distribution and abundance of the splendid tiger beetle in the state.
References and Additional Information
Dawson, R. W., and W. Horn. 1928. The tiger beetles of Minnesota. University of Minnesota Agricultural Experiment Station Technical Bulletin 56. 13 pp.
Pearson, D. L., C. B. Knisley, and C. J. Kazilek. 2006. A field guide to the tiger beetles of the United States and Canada: identification, natural history, and distribution of the Cicindelidae. Oxford University Press, New York. 227 pp. + plates.