Montana Field Guide

The following is taken from Wallis (1961), Spanton (1983), Acorn (2001), and Spomer (2009). Body length is 12-14 mm; generally uniformly black and immaculate above, black underneath (rarely iridescent purple, blue, blue and green). Forehead without hairs, upper lip (labrum) of both sexes and all forms longer than wide, light, mottled, tan or black, and is unique except for Boreal Long-lipped Tiger Beetle (C. longilabris) [but see Diagnostic Characteristics]. Surface of elytra is shiny and smooth with punctures few and indistinct in transverse rows. Elytra markings, if present, are a single, thin and remnant middle band only. Cicindela montana is a synonym for this species in older literature (Wallis 1961, Hooper 1969, Acorn 2001).

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, Leonard and Bell 1999). Adult Cicindela nebraskana a spring-fall species, late March to early October but mostly May and August, with stragglers the months in between (Spanton 1983, Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, Brust and Hoback 2005). In Montana, adults present at least early May to early September (Hendricks and Lesica 2007, Nate Kohler personal communication).

The following largely comes from Spanton (1983), Acorn (2001) and Spomer (2009). Most similar to the Boreal Long-lipped Tiger Beetle (C. longilabris), which some authors consider conspecific with C. nebraskana, based on molecular evidence (Spomer 2009, Pearson et al. 2015). Distinguished from Boreal Long-lipped Tiger Beetle (C. longilabris) by the immaculate elytra with a smooth and shiny appearance (only a thin remnant middle band if any). Underside of C. nebraskana is typically black, labrum of female partially or completely dark (often white in males however, but almost always white in both sexes of C. longilabris). C. nebraskana typically occupies clay soils in open grassland instead of sandy soils in grassy openings of conifer forests, but widespread areas of intergradation exist between C. nebraskana and C. longilabris. All morphs (including black) of Cow Path Tiger Beetle (C. purpurea auduboni) have hairy foreheads, elytra always with white tip.

Non-migratory but capable of dispersal. When wings fully developed (macropterous), it is a good flier, fast runner, and very active (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 nebraskana prefers shortgrass prairies, forest-grassland transitions and parklands, open grassy spaces between ground squirrel mounds, paths, roadside ditches, sometimes in foothill pine forests, alkaline flats, often associated with clayey soils but also sandy blowouts, to above 10,000 feet (3048 m) elevation (Criddle 1907, Vaurie 1950, Wallis 1961, Ferris 1969, Hooper 1969, Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, Brust and Hoback 2005, Kritsky and Smith 2005). In Montana, habitat poorly described but includes two tracks, unpaved roads, road cuts, stabilized dunes with sandy soil, livestock trails in grassland and shrubsteppe, to at least 6660 feet (2030 m) elevation (Hendricks and Lesica 2007, Nate Kohler personal communication).

Larval and adult tiger beetles are predaceous. In general, both feed considerably on ants (Wallis 1961, Knisley and Schultz 1997). Diet of adult Cicindela nebraskana not reported (Larochelle and Larivière 2001, Brust and Hoback 2005) but probably small insects and spiders.

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, Knisley and Schultz 1997). Cicindela nebraskana has a broad range of ecological tolerance (eurytopic). Larval burrows are often scattered among open patches near sparse vegetation, short (8-20 cm) with funnel shaped opening (Larochelle and Larivière 2001, Pearson et al. 2015). Adults are diurnal, generally solitary, moderately wary but easy to approach. They run through grass when pursued or take flight, flight in straight line up to 10 m. Predators are not reported but probably include asilid (robber) flies.. Other associated tiger beetle species include C. decemnotata, C. purpurea, C. tranquebarica, and C. longilabris (Vaurie 1950, Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, Hendricks and Lesica 2007).

The life cycle of Cicindela nebraskana is probably 3 years, 2 years as larvae (Acorn 2001, Brust and Hoback 2005). Larval burrows are short with a funnel-like opening. Mating reported in July and August, fresh emerged adults (tenerals) in September, then overwinter and reach sexual maturity the following spring. Copulations observed with subspecies of Boreal Long-lipped Tiger Beetle (C. longilabris) (Larochelle and Larivière 2001). No information for Montana.

Not considered rare or in need of special conservation management (Knisley et al. 2014). Prairie grassland, shrubsteppe, and grassy openings and meadows in foothill pine forest habitat experience vegetation encroachment as succession proceeds, and benefit from disturbance that retains a mosaic of successional conditions. Exotic grasses, such as cheatgrass, could become a problem at local scales. 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 burning in late autumn could also be a useful tool for sustaining habitat once larvae and adults are in overwinter burrows, but should be used cautiously in sagebrush sites which may take decades or longer to recover from fire.