Rare Species Guide

  Synonyms

Cicindela fulgida elegans

  Basis for Listing

The crimson saltflat tiger beetle (westbournei subspecies) was first observed in Minnesota in 1978 in Kittson County. A second location was discovered about two miles to the south in 1981. There are no other localities of this subspecies known in Minnesota. The two known locations were revisited in 2000 and 2004, and both locations were underwater with dense growth of cattails as a result of the roadside ditches at these sites being deepened. Although it appears that this subspecies no longer occurs at the sites where it was previously documented, there is potentially suitable habitat in the state that has not yet been surveyed. The crimson saltflat tiger beetle (westbournei subspecies) was listed as a threatened species in 1996.

  Description

Adult crimson saltflat tiger beetles (westbournei subspecies) are small, averaging 10-11 mm (0.39-0.43 in.) long, and they are dark metallic red (some populations have occasional blue or green specimens) with 3 well-separated lunulate ivory markings on each wing cover. Unlike C. fulgida fulgida, which is first bright red and then darkens with age, the subspecies westbournei is dark throughout adulthood.

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).

  Habitat

The crimson saltflat tiger beetle (westbournei subspecies) is found in open, sparsely vegetated, moist saltflats (often in shallow roadside ditches) with salt grass (Distichlis spicata), red saltwort (Salicornia rubra), and a thin crust of magnesium sulfate. It has the same specialized habitat requirements as C. fulgida fulgida (Willis 1967), but is found further north.

  Biology / Life History

Adult crimson saltflat tiger beetles (westbournei subspecies) emerge in the fall (as early as mid-August), begin hunting until colder weather, and then burrow underground for the winter. They re-emerge in early spring (mid-May), begin mating and laying eggs, and then slowly die-off as the 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 two 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

Changes in hydrology that result in drainage or flooding of habitat are a potential threat to this subspecies, as are run-off from roadways, roadside vegetation management, pesticide application on nearby fields, heavy vehicle traffic, and conversion of sites for agricultural uses (Steffens 2005).

  Conservation Efforts in Minnesota

It is not certain if the crimson saltflat tiger beetle (westbournei subspecies) still survives in Minnesota. Further work to locate and survey undisturbed saline areas in northwestern Minnesota is needed to assess this subspecies' population status in Minnesota.

  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.

Steffens, W. P. 2005. Rare tiger beetle surveys in central and northwest Minnesota, Fall 2004. Report submitted to the County Biological Survey, Minnesota Department of Natural Resources. 11 pp.

Willis, H. L. 1967. Bionomics and zoogeography of tiger beetles of saline habitats in the central United States (Coleoptera: Cicindelidae). University of Kansas Science Bulletin 47(5):143-313.