Montana Field Guide

The following is taken from Pearson et al. (2015). This species length is 14-21 mm and it is the largest tiger beetle in Montana. It is bright coppery red above (rarely bright metallic green in northeastern Wyoming) with very broad maculations connected to each other, sometimes to the extent that the first and rear maculations are obscure. It is purple metallic below. There is a broad zone of intergradation with C. formosa generosa, which is dark brown above, metallic green below with coppery reflections (see generosa subspecies account). C. formosa fletcheri, described from specimens collected along the Marias River (Criddle 1925), falls within the range of variation for C. f. formosa and is considered a junior synonym (Wallis 1961, but see French et al. 2021).

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 formosa formosa in the southern part of its range are active from March to July and again August to October; at higher latitudes some adults may be present throughout summer (Larochelle and Larivière 2001, Pearson et al. 2015). In Montana, some adults are active from mid-April to at least mid-September (Criddle 1925, Nate Kohler personal communication).

The following comes largely from Pearson et al. (2015). C. f. formosa differs from C. formosa generosa in coloration (bright coppery red above instead of dark brown, metallic purple below instead of metallic green with coppery reflections), and from C. f. gibsoni in coloration (bright coppery red above instead of dark red to purple above, metallic purple below instead of metallic bluish-violet), and maculations (broad but more distinct instead of maculations sometimes expanded to cover much of the elytra except for a dark wedge down the midline). Differs from the similarly colored and sometimes sympatric Blowout Tiger Beetle (C. lengi) by its bulkier larger size, shorter and wider labrum and the front (shoulder) maculation is relatively shorter. The maculations are generally thicker overall.

This species is non-migratory but capable of dispersal. When wings are fully developed (macropterous), it is a strong, agile 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). Across the range Cicindela formosa formosa prefers dry upland sandy areas with little vegetation and no standing water (sand dunes, sand hills), often in short grass and forbs near dune margins, ditches, road cuts, sandy fields, sand flats, and sandy beaches along water courses (Wallis 1961, Acorn 2001, Larochelle and Larivière 2001, Pearson et al. 2015). In Montana, found in stabilized sandy dunes, sandy road cuts and paths, and sandy beaches along water courses (Nate Kohler personal communication).

Larval and adult tiger beetles are predaceous. In general, both feed considerably on ants (Wallis 1961, Knisley and Schultz 1997). Larval Cicindela formosa formosa feed on ants, adults on ants, grasshoppers, carabid beetles (Larochelle and Larivière 2001), and probably other 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 are 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 formosa formosa has a narrow range of ecological tolerance (stenotopic). Larval burrows are up to 33 cm deep in sand with a pit near the entrance used for trapping insects, burrows closed in summer. Adults are diurnal, and gregarious (often occurring in large numbers). They are often found sunning on warm soil, become active at 15-20°C, and burrow in sand to escape excessive heat. Predators include asilid (robber) flies. Escapes by flying quickly, typically short distances (< 10 m), making an audible buzz while in flight, seeking cover in vegetation once landing. Wary and difficult to approach. Other associated tiger beetle species include Blowout Tiger Beetle (C. lengi) and Festive Tiger Beetle (C. scutellaris) (Larochelle and Larivière 2001). Sometimes occurs in patchy colonies associated with sandy habitats (Pearson et al. 2015). Larvae and newly emerged adults overwinter in burrows (Acorn 2001), larvae up to 3 m deep and adults to 1m (Criddle 1925, Larochelle and Larivière 2001).

The life cycle of Cicindela formosa formosa is 2-3 years, depending on elevation and latitude (Larochelle and Larivière 2001, Pearson et al. 2015). Mating reported April to June, coition lasts 7-10 minutes (Larochelle and Larivière 2001). Females oviposit eggs in sand while burrowing to depths of 60 cm (Brust et al. 2012).

Not considered rare or in need of special conservation management (Knisley et al. 2014), but see account for C. f. gibsoni. Sandy habitats favored by this subspecies experience vegetation encroachment and stabilization as succession proceeds, and benefit from disturbance that retains early succession conditions. 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, as could appropriate use of controlled burns (Knisley 2011).