Montana Field Guide

The following comes from Wallis (1961), Graves and Brzoska 1991, Leonard and Bell (1999), and Pearson et al (2015). The body length is 11-13 mm. It is short-legged and robust. The rear end is rounded, and elytra margins are relatively parallel-sided. Above, it is uniformly colored from head to elytra, usually reddish-maroon but sometimes olive-green. Maculations often reduced to spots or short bands. The middle maculation, if present, is reduced to a lateral triangular spot. A broad ivory border on outer edge of elytra varies from complete to narrowly interrupted posterior of rear leg; many individuals in northern Midwest and prairie provinces may have maculations coalesced into a distinct marginal band along entire edge of elytra. Undersides are iridescent greenish-blue or greenish-purple. Labrum white in males, dark or black in females, mandible with 3 teeth. Front and top of head with white hairs, less in females (hairs restricted to base of eyes) than males.

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 scutellaris a spring-fall species, the lecontei subspecies with an active period of April to October but varies somewhat (Larochelle and Larivière 2001, Pearson et al. 2015); April to June and September to October in Nebraska and Ohio (Carter 1989, Graves and Brzoska 1991), April to early July and late August to October in Indiana (Knisley 1979). In Montana, the active period is not reported but probably similar to the scutellaris subspecies, which is active at least from early April to early July and again in September (Nate Kohler personal communication, iNaturalist 2023).

The following is taken from Carter (1989) and Pearson et al. (2015). The lecontei subspecies of the Festive Tiger Beetle, with its uniform dull reddish-maroon to olive-green color, reduced maculations, and broad ivory-colored border along the outer edge of the elytra, is not likely confused with any other North American tiger beetle. The middle maculation, if present, is reduced to a short bulge off of the broken or continuous ivory border.

Non-migratory but capable of dispersal. When wings are fully developed (macropterous), it is a good 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, all subspecies of Cicindela scutellaris, including C. s. lecontei, are associated with sandy soils and habitats with sparse vegetation: stabilized margins of sand dunes and dry grassy blowouts, sandy road cuts, sand flats, sand and gravel pits, riverine sand bars, and sandy soils beneath open pine and mixed pine-oak woodlands prior to later stages of succession (Shelford 1907, Vaurie 1950, Wallis 1961, Knisley 1979, Carter 1989, Graves and Brzoska 1991, Larochelle and Larivière 2001, Kritsky and Smith 2005, and Pearson et al. 2015). In Montana, the habitat is poorly described but likely similar to that reported for C. s. scutellaris, which includes sand dunes, blowouts, and riverine sandbars (Nate Kohler personal communication, iNaturalist 2023).

Larval and adult tiger beetles are predaceous. In general, both feed considerably on ants (Wallis 1961, Knisley and Schultz 1997). Diet of adult Cicindela scutellaris lecontei in the field includes live and dead ants, cutworms, beetles (carabids), grasshoppers (acridids), and in captivity, carabids, caterpillars, and dead fish. Diet of larvae in the field includes carabid larvae, gomphid and libellulid dragonflies (Larochelle and Larivière 2001).

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 scutellaris lecontei has a narrow range of ecological tolerance (stenotopic). Adults are diurnal, especially mid-day during the hottest periods, are gregarious, very wary and often run through sparse vegetation. They hide in slit holes or under cover in grassy sand areas on cloudy days (Vaurie 1950, Larochelle and Larivière 2001, and Pearson et al. 2015). Predators of adults include birds (Gray Catbird, grouse) and spiders, probably also robber flies (Asilidae). When disturbed, makes fast looping flights of 3-4 m, and also digs in sand. Emits a strong fruity scent when captured. Larvae often parasitized by bombyliid flies: Anthrax sp. (Shelford 1908, Larochelle and Larivière 2001, and Pearson et al. 2015). Associated tiger beetle species include C. denverensis, C. formosa, C. (= Cicindelidia) punctulate, C. sexgutta, and C. tranquebarica (Criddle 1907, Knisley 1979, Carter 1989, Graves and Brzoska 1991, Larochelle and Larivière 2001, Kritsky and Smith 2005).

The life cycle of Cicindela scutellaris lecontei is 2 years (Larochelle and Larivière 2001, and Pearson et al. 2015). Both third-instar larvae and adults overwinter, adults emerging in fall, then overwintering and reemerging in spring to mate. Interspecific copulation observed with C. sexgutta and C. tranquebarica. Mating is probably April to July for the subspecies occurring in Montana. Copulation lasts 1-15 min (mean = 4 min). Females dig oviposition holes 35-60 mm deep during the day and eggs are laid in dry sand. Larval burrows are vertical and 25-71 cm deep, burrows deeper in winter, and closed in mid-summer. The duration of larval life is 12-13 months, pupation in August in a chamber 25-50 mm deep branching 5-7 cm off of the main burrow. Fresh adults (tenerals) emerge in August and September (Criddle 1907, 1910; Shelford 1908, Vaurie 1950, Larochelle and Larivière 2001, and Brust et al. 2012). No information on reproductive characteristics for Montana.

Not considered rare or in need of special conservation management (Knisley et al. 2014). Sandy habitats favored by this subspecies experience vegetation encroachment and stabilization as succession proceeds (Shelford 1907, Knisley 1979), and benefit from disturbance that retains a mosaic of successional 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 in late autumn could also be a useful tool for sustaining habitat once larvae and adults are in overwinter burrows.