Montana Field Guide

The following is taken from Wallis (1961), Kippenhan (1994), Acorn (2001), Pearson et al (2015). Body length is 11-14 mm. Relatively uniform rich-brown above but some individuals are greenish. Maculations are complete, moderately heavy (thick), often reduced to dots instead of crescents or lines, marginal line absent on middle of elytra, middle band with abrupt bend to rear forming an “elbow.” Below is metallic coppery, especially on thorax. Forehead with only a few hairs (setae) above eyes, a small cluster near the inner front edge of the eyes; first antennomere with 3 sensory setae and 5 or fewer accessory setae, labrum short with 1 tooth.

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, Pearson et al. 2015). Adult Cicindela oregona guttifera a spring-fall species, found mostly May-June and August (Larochelle and Larivière 2001); mid- May to mid-August in Colorado (Kippenhan 1994). In Montana, this subspecies, including perhaps intergrades, reported early April to mid-October (Nate Kohler personal communication, iNaturalist 2024).

The following comes largely from Wallis (1961), Kippenhan (1994), Acorn (2001) and Pearson et al. (2015). Most similar in appearance to the Twelve-spotted Tiger Beetle (Cicindela duodecimguttata) where the species overlap along the eastern slopes of the Rocky Mountains. C. duodecimguttata usually has a distinct or remnant short white marginal line along middle of the outer edge of the elytra, lacking in C. oregona, and the forehead of C. oregona is mostly hairless, not hairy as with C. duodecimguttata. Dispirited Tiger Beetle (C. depressula) has a middle band (maculation) with a shallow, wave-like bend to the rear with no sharp turn, whereas C. oregona has a sharp bend rearward, forming a distinct “elbow.” Bronze Tiger Beetle (C. repanda) has a distinct, if incomplete, marginal band on the outer edge of the elytra that is lacking in C. oregona, and the forehead is hairy, not mostly hairless. The subspecies C. oregona oregona has an upper surface usually dark brown but sometimes green, the maculations are complete but thin and often disrupted, and the undersurface is metallic blue, not metallic coppery. Intergrades between the two C. oregona subspecies present in Montana have intermediate characteristics.

Non-migratory but capable of dispersal. When wings fully developed (macropterous), generally a strong 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). Cicindela oregona guttifera is found close to water on sparsely vegetated soils of various fluvial habitats, mudflats, alkali lake shores, salt marshes, livestock reservoirs, edges of ponds, freshwater lakes, sand and gravel banks of rivers, streams and creeks, sand bars, dunes, other river sand deposits (Vaurie 1950, Wallis 1961, Knisley 1984, Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, and Pearson et al. 2015). In Montana, habitat similar to elsewhere inland, including dunes and two-tracks near rivers, sand bars and riverbanks, along streams, shores of freshwater lakes and reservoirs, reclamation pond edges, fishing access sites (Nate Kohler personal communication; iNaturalist 2024).

Larval and adult tiger beetles are predaceous. In general, both feed considerably on ants (Wallis 1961, and Knisley and Schultz 1997). Adult foods of Cicindela oregona guttifera not described but probably includes various small arthropods. Also likely to scavenge dead and dying arthropods. Larvae likely to be cannibalistic when coming into contact (Larochelle and Larivière 2001, Kippenhan 2002, Rogers and Rogers 2004, and Lyons 2015).

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 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, and Pearson et al. 2015). Cicindela oregona guttifera has wide range (eurytopic) of ecological tolerance. Adults are diurnal and gregarious, becoming active at about 15°C and remaining so at 25-38°C, escapes by flying up to 3 m, quite wary, may release defensive secretions when captured (Schultz and Hadley 1987, and Larochelle and Larivière 2001). Predators of adults are not described but probably include frogs, birds, spiders and robber flies (asilids); larvae probably parasitized by bee flies (bombyliids) and tiphiid wasps. Associated tiger beetle species include Cicindela duodecimguttata, C. hirticollis, C. repanda, and C. tranquebarica (Kippenhan 1994, Acorn 2001, Larochelle and Larivière 2001, and Pearson et al. 2015).

Life cycle of Cicindela oregona guttifera is 2 years. Details of reproduction is not well-described, but probably similar to other subspecies. Mating is in May and July; females oviposit in May and July. Larval burrows usually clustered, 12-30 cm deep and 1.5-3.0 mm diameter (depending on instar), and vertical if on flats, horizontal if in banks, excavated in open and moist loose sand near water. Overwinter as third-instar larvae, reemerge in spring then pupate in early summer, sexually immature adults (fresh tenerals) emerge in August and September then overwinter before reemerging the following spring to mate. Interspecific copulation observed with Cicindela duodecimguttata, C. repanda, and C. willistoni (Vaurie 1950, Acorn 2001, Larochelle and Larivière 2001, Lyons 2015, and Pearson et al. 2015). Mating observed in Montana in late May and late July (iNaturalist 2024), otherwise no information.

Not considered rare or in need of special conservation management (Knisley et al. 2014). Cicindela oregona guttifera may be sensitive to altered river and stream flows through damming and channelization, which alters sediment deposition, especially sand. Retention and restoration of natural stream and river sediment-deposition processes will benefit this subspecies. Early-succession habitats near water favored by this subspecies also experience vegetation encroachment as succession proceeds for whatever reason (Shelford 1907, and Knisley 1979), and benefit from disturbance that retains a mosaic of successional conditions. Some colonies (particularly larval burrows) could be impacted by trampling from livestock overgrazing or access to water sources at lakes, reservoirs, streams and rivers (Knisley 2011). Grazing at appropriate times and stocking levels, however, could be beneficial by keeping vegetation cover more open.