Montana Field Guide

The following is taken from Wallis (1961), Willis (1966), Kippenhan (1994), Acorn (2001), and Pearson et al (2015). The body length is 10-13 mm. Shiny dark brown, brown, reddish-brown, and rarely dark green or blue above. Three distinct pale maculations (complete) and connected with a marginal band along the outer edge of the elytra. Lacks a basal dot at the anterior corner of the shoulder maculation, thus the shoulder (humeral) maculation is “J” shaped, not “G” shaped. Elytra is distinctly widened in the middle, especially in females. Moderately iridescent blue-green to copper-green below. Forehead is hairy, with decumbent (lying flat) setae on forehead and body, labrum is short with one tooth. C. n. knausii, the only subspecies in Montana, is reddish-brown to brown above with moderately wide maculations, the base of the middle maculation connected broadly forward but narrowly to the rear with the marginal band.

Tiger beetle life cycles fit two general categories based on adult activity periods. “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. The life cycle may take 1-4 years. “Summer” beetles emerge as adults in early summer, then mate and lay eggs before dying. The life cycle may take 1-2 years, possibly longer depending on latitude and elevation (Kippenhan 1994, Knisley and Schultz 1997, and Leonard and Bell 1999). Adult Cicindela (= Ellipsoptera) nevadica is a summer species; for C. n. knausii, the subspecies occurring in Montana, typically late May to August (Larochelle and Larivière 2001, Pearson et al. 2015, and iNaturalist 2023). June to July in Colorado (Kippenhan 1994), June to August in Nebraska (Carter 1989), June to July in North Dakota (Kritsky and Smith 2005, and iNaturalist 2023) probably June to July or August in Alberta (Acorn 2001). No published information on phenology in Montana, but likely similar to Alberta, North Dakota, and Colorado.

The following comes from Wallis (1961), Willis (1966), Kippenhan (1994), Acorn (2001), and Pearson et al. (2015). The “J” shaped humeral maculation (lacking a basal dot) is diagnostic in our region. The Hairy-necked Tiger Beetle (Cicindela hirticollis) has a similar elytra pattern but with the humeral maculation “G” shaped (basal dot present), is larger, does not occur in saline habitats, and has upright hairs (setae) rather than flattened ones. Further analyses of maculation patterns, genitalia, and DNA may show that this species is comprised of three or four cryptic species (Pearson et al. 2015).

Non-migratory but capable of dispersal. When wings are fully developed (macropterous), it is a strong flier, fast runner, and has been observed wading through shallow water (Larochelle and Larivière 2001).

Adult and larval tiger beetle habitat is essentially identical, the larvae live in soil burrows (Knisley and Schultz 1997). Across the range Cicindela (= Ellipsoptera) nevadica is associated with open ground of saline and non-saline flats, alkaline or sandy soils, wet muddy ground, ditches, saline margins of lakes, reservoirs, marshes, ponds, rivers, in grasslands and prairies always in presence of sparse vegetation and usually near water (Vaurie 1950, Willis 1966, Knisley 1984, Carter 1989, Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, Spomer 2004, Kritsky and Smith 2005, and Pearson et al. 2015). In Montana, habitat is poorly described but includes large moist alkali flats (Vaurie 1950).

Larval and adult tiger beetles are predaceous. In general, both feed considerably on ants (Wallis 1961, and Knisley and Schultz 1997). Adult and larval diet not described (Larochelle and Larivière 2001) but probably includes a variety of small insects and other invertebrates.

Larval tiger beetles live in burrows and molt through three instars to pupation, which also occurs in the larval burrow. 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, and Knisley and Schultz 1997). Most subspecies of Cicindela (= Ellipsoptera) nevadica, including C. n. knausii, have a narrow range of ecological tolerance (stenotopic). Larval burrows excavated among sparse vegetation in vicinity of hummocks, along margins of small flats, and along sloping stream banks. Larvae can survive flooding (hypoxia) for more than 130 hours, adults for more than 15 hours (Larochelle and Larivière 2001, Brust and Hoback 2009). Adults are both diurnal and nocturnal, and gregarious. Seen going in and out of mud cracks on moist alkali flats, often stop to drink water on hot days. Attracted to artificial lights at night. Very wary, sometimes difficult to approach. When pursued makes frequent short flights. Predators apparently not described but probably include asilid (robber) flies, various birds, and bats. C. nevadica are especially sensitive to ultrasound in the range of 25-50 kHz and makes nocturnal flights (Vaurie 1950, Yager et al. 2000, and Larochelle and Larivière 2001). Associated tiger beetle species across the range include C. (=Eunota) circumpicta, C. (=Ellipsoptera) cuprascens, C. (=Ellipsoptera) fulgida, C. (=Ellipsoptera) hamata, C. (=Cicindelidia) hemorrhagica, C. hirticollis,C. (=Ellipsoptera) marutha, C. (=Cicindelidia) nigrocoerulea, C. (=Cicindelidia) pamphila, C. (=Cicindelidia) punctulate, C. repanda, C. (=Ellipsoptera) sperata, C. (=Eunota) togata, and C. tranquebarica (Spomer and Higley 1993, Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, Spomer 2004, and Pearson et al. 2015).

Life cycle of Cicindela (= Ellipsoptera) nevadica is probably 2 years. Overwinters as larvae (Acorn 2001). Pairs of C. n. knausii noted July to August in the north, late May to July farther south (Vaurie 1950, Larochelle and Larivière 2001, iNaturalist 2023). Adult females oviposit from the soil surface, depth of oviposition is not known. Larval burrows about 22-35 cm deep, duration of larval stage unknown but probably 2 years (Acorn 2001, Larochelle and Larivière 2001, Brust et al. 2012, and Pearson et al. 2015). No information about reproductive characteristics in Montana.

Not considered rare or in need of special conservation management (Knisley et al. 2014) except for four range-restricted subspecies, one of which is Federally Listed as Endangered. None of these occur in Montana, the closest to Montana is Cicindela (= Ellipsoptera) nevadica makosika in the Badlands of southwestern South Dakota (Spomer 2004). Maintaining areas of open saline soils, which is tied to fluctuations in surface and subsurface water levels, is probably of most importance to Cicindela nevadica in Montana. Intense irrigation, saline wetland drainage, or other forms of water diversion could reduce the water table at and near the surface and eliminate areas of suitable habitat especially needed by the larvae. Encroachment of open areas by native or exotic plants that invade saline soils might become a problem locally. Local disturbance could also be a problem for some populations where larval burrows are damaged or destroyed by trampling from livestock drawn to water sources, but grazing at appropriate times and stocking levels could also be beneficial by keeping vegetation cover more open (Knisley 2011).