Montana Field Guide

The following comes from Pearson et al. (2015). The Badlands tiger beetle length is 12-14 mm and mostly found in various shades of metallic green to purplish or reddish-green, sometimes black. Maculations are generally thick, often reduced in number (but complete in the subspecies C. decemnotata decemnotata in Montana). The middle maculation is a line curving posteriorly at a sharp angle toward midline and does not reach outer edge of elytra. It is entirely metallic blue-green below.

Tiger beetle life cycles fit two general categories. “Spring-fall” beetles emerge as adults in late summer and fall, then overwinter in burrows before emerging again in spring when mature and ready to mate and lay eggs. This life cycle may take 1-4 years. “Summer” beetles emerge as adults in early summer, then mate and lay eggs before dying. This life cycle may take 1-2 years, possibly longer depending on latitude and elevation (Knisley and Schultz 1997, Leonard and Bell 1999). Adults of Cicindela decemnotata across its range are active from mid-March to July and again in early September to mid-October and at higher elevations from late June to late August (Larochelle and Larivière 2001, Pearson et al. 2015). In Montana, generally early April to June and late August to September (Knisley et al. 2012, Nate Kohler personal communication), May to early July and September to early October in the Centennial Valley (2030 m elevation) of Beaverhead County (Hendricks and Roedel 2001, Hendricks and Lesica 2007, Winton 2010).

The following is taken largely from Pearson et al. (2015). Anterior maculations are two dots projecting only slightly toward inner edge of the elytra. Thicker maculations, a middle maculation that does not reach the outer edge of the elytra, the sharp angle at which the middle maculation bends posteriorly with an indistinct foot near the midline, the undersides entirely metallic green without coppery tones on thorax, distinguish this species in Montana from the Green Claybank Tiger Beetle (Cicindela denverensis) and Common Claybank Tiger Beetle (Cicindela limbalis).

This species is non-migratory but capable of dispersal. When wings are fully developed (macropterous), it is a strong flier and fast runner (Larochelle and Larivière 2001).

Adult and larval tiger beetle habitat is essentially identical. The larvae live in soil burrows (Knisley and Schultz 1997). Cicindela decemnotata are found in open ground, badlands, stabilized dunes, sparsely vegetated grassland, open pine forest, sagebrush steppe, saline flats, brushy areas with clay, sand, or gravelly soils. Road cuts, dirt paths, livestock paths (Hooper 1969, Acorn 2001, Larochelle and Larivière 2001, Kritsky and Smith 2005, Hendricks and Lesica 2007, and Pearson et al. 2015).

Larval and adult tiger beetles are predaceous. In general, both feed considerably on ants (Wallis 1961, and Knisley and Schultz 1997). Diet is unreported for Cicindela decemnotata but probably mostly small insects and spiders.

Larval tiger beetles live in burrows and molt through three instars to pupation. Adults make shallow burrows in soil for overnight protection, deeper burrows for overwintering. Adults are sensitive to heat and light and most active during sunny conditions. Excessive heat during midday on sunny days drives adults to seek shelter among vegetation or in burrows (Wallis 1961, Knisley and Schultz 1997). Cicindela decemnotata has a wide range of ecological tolerance (eurytopic). Diurnal, solitary; often sunning on warm soil, attracted to night lights. Predators not reported but likely include robber flies. Escapes by flying quickly and seeking cover in vegetation rather than alighting in open ground. Wary and difficult to approach. Associated tiger beetle species include Cow Path Tiger Beetle (C. purperea), Boreal Long-lipped Tiger Beetle (C. longilabris) and Big Sand Tiger Beetle (C. Formosa) (Larochelle and Larivière 2001, Hendricks and Lesica 2007) and likely includes others (Kritsky and Smith 2005). Apparently occurs in patchy colonies (Pearson et al. 2015).

Mating is reported May to June, duration brief (Larochelle and Larivière 2001). In Montana late May to early July (Hendricks and Lesica 2007). Larvae take two years to develop to adults but possibly three years at higher elevations and latitudes (Pearson et al. 2015). Adults emerge in fall and then overwinter (Acorn 2001).

This species is not considered rare or in need of special conservation management (Knisley et al. 2014). Some colonies (particularly the larval burrows) could be impacted by trampling through livestock overgrazing, but grazing at appropriate times and stocking levels could also be beneficial by keeping vegetation cover more open (Knisley 2011). Prescribed fire may have a negative impact on abundance for the first year post-burn (Winton 2010).