Montana Field Guide

The following is taken from Pearson et al. (2015). The length is 14-21 mm and is one of the largest North American species in the tribe Cicindelini and the largest tiger beetle in Montana. It is dark above, with the same color on the head, thorax and abdomen. The color is variable, from dark brown to bright coppery red, dark red, purple, greenish red, and rarely bright green. Ivory white maculations found on the elytra are also variable, from almost completely absent to covering most of elytra, but most often wide and distinct. Ventral metallic color varies from dark green to blue or purple. Three subspecies are found in Montana, C. f. formosa, C. f. generosa, C. formosa gibsoni (see the respective species accounts).

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 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, at least some adults are active from mid-April to early October (Hendricks and Lesica 2007, Winton 2010, Nate Kohler personal communication).

The following largely comes from Pearson et al. (2015). This species differs from the similarly colored and sometimes sympatric Blowout Tiger Beetle (C. lengi) by its bulkier larger size, shorter and wider labrum. Also the front (shoulder) maculation is relatively shorter, maculations generally thicker overall.

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 are essentially identical, the larvae live in soil burrows (Knisley and Schultz 1997). Across the range Cicindela formosa prefers dry upland sandy areas with little vegetation and no standing water, often in short grass and forbs near dune margins. In the east, found in road cuts, sandy fields, sea shore dunes and pine-oak barrens and scrub forest. In the west, more restricted to extensive sandy blowouts and dunes but also sandy road cuts, sandy beaches along watercourses, and sand flats (Wallis 1961, Hooper 1969, Acorn 2001, Larochelle and Larivière 2001, Kritsky and Smith 2005, Pearson et al. 2015). In Montana, it is found in stabilized sandy dunes, sandy road cuts and paths, and sandy beaches along water courses (Hendricks and Roedel 2001, Hendricks and Lesica 2007, Winton 2010, 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 feed on ants, adults on ants, grasshoppers, carabid beetles, chrysomelid beetles, scarabid beetles, sphecid wasps (Willis 2000, 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 has a narrow range of ecological tolerance (stenotopic). Larval burrows are up to 50 cm deep in sand (Leonard and Bell 1999). Adults are diurnal and gregarious (often occurring in large numbers). 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 short distances to 100 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 Saint Anthony Dune Tiger Beetle (C.arenicola) (only in Montana), Badlands Tiger Beetle (C. decemnotata), Blowout Tiger Beetle (C. lengi), Boreal Long-lipped Tiger Beetle (C. longilabris), Prairie Long-lipped Tiger Beetle (C. nebraskana), Festive Tiger Beetle (C. scutellaris) (Larochelle and Larivière 2001, Hendricks and Lesica 2007, Winton 2010). 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 30 cm (Larochelle and Larivière 2001).

The life cycle of Cicindela formosa is 2-3 years, depending on elevation and latitude (Larochelle and Larivière 2001, Pearson et al. 2015). Mating is reported from 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). In Beaverhead County, Montana (2030 m elevation) mating has been observed during mornings in late May to mid-July (Hendricks and Roedel 2001, Hendricks and Lesica 2007, Hendricks personal observations) on sunny days when air temperatures were 21-27°C. Numerous larval burrows were also present.

Not considered rare or in need of special conservation management (Knisley et al. 2014), but see account for C. formosa gibsoni. Sandy habitats favored by this species 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 (Knisley 2011). Prescribed fire is also a useful management tool (Winton 2010).