Cicindela hirticollis rhodensis Calder, 1916
Hairy-necked Tiger Beetle
Basis for Listing
The Rhode Island Hairy-necked Tiger Beetle (Cicindela hirticollis ssp. rhodensis) was first observed in Minnesota in 1960 at two locations along the Lake Superior shoreline near Duluth in St. Louis County (North Shore Highlands Subsection), which represents the western periphery of the subspecies range. It was observed in this area on several occasions until 1974. In 1996, the Rhode Island Hairy-necked Tiger Beetle was listed as a species of special concern. No further efforts to document the species were made until it was relocated at one of the two original collection sites in 2003 (Steffens 2004, 2009). Habitat loss to development and recreational use of beach habitats has been ongoing in this area, potentially threatening the last known site. Given its restricted distribution and the vulnerability of its habitat, the status of the Rhode Island Hairy-necked Tiger Beetle was elevated to endangered in 2013.
Adult Rhode island Hairy-necked Tiger Beetles average 10-15 mm (0.39-0.59 in.) in length and are dull brown to reddish brown in color, with thin or incomplete pale maculations above (Pearson et al. 2015). When they are freshly emerged in the fall, the side of the thorax has a large tuft of long white 'hairs'. The hairs are abraded during overwintering underground and then experience further wear the following spring and summer. At that time, the Rhode Island Hairy-necked Tiger Beetle can be confused with the smaller (10-13 mm [0.39-0.51 in.]) and extremely abundant Bronzed Tiger Beetle (Cicindela repanda); however, the posterior tips of the wing covers (elytra) are more pointed in C. hirticollis, versus more rounded in C. repanda.
Tiger beetle larvae are mostly white and somewhat grub-like (Pearson et al. 2015). The portions of their bodies that are exposed in their burrow entrances are usually the same color and texture as the surrounding soil surface allowing them to blend in with the soil (Pearson et al. 2015). Tiger beetle larvae have eyes with dense photoreceptors that give them detailed focusing ability and three-dimensional visual perception (Pearson et al. 2015).
In Minnesota, the Hairy-necked Tiger Beetle (ssp. rhodensis) is only known in Minnesota from sandy beaches that occur along the Lake Superior shoreline near Duluth. The other subspecies of the Hairy-necked Tiger Beetle that occurs in Minnesota is known from sandy lakeshores and large sandy river systems away from Lake Superior.
Biology / Life History
Adults of this species may emerge in the fall, feed until cold weather, and then burrow underground for the winter. Some individuals may also overwinter as larvae (Pearson et al. 2015). Adults emerge the following spring and begin feeding, mating, and laying eggs. They slowly die off as the season progresses.
Tiger beetles prey on small insects and other arthropods and are visual hunters. Adults will either chase their prey or wait in a shaded area and ambush prey as it wanders by (Pearson et al. 2015). They often chase their prey in short, fast bursts with brief stops in between runs. These stops are necessary for orientation as tiger beetles can run so fast that they cannot see the prey they are pursuing.
The colored front wings (elytra) of tiger beetles are hardened protective coverings for the abdomen. The transparent hind wings are the flight wings and are folded beneath the elytra when the beetle is not in flight. The elytra do not contribute to flight but are held out of the way of the hind wings. When disturbed, tiger beetles may take short, low flights to escape. These escape flights and the ability to run quickly are their main defenses against predators. Tiger beetles are also usually well camouflaged in their environment.
Tiger beetle larvae dig burrows in which they live and secure prey. The burrows of the Rhode Island Hairy-necked Tiger Beetle are vertical and constructed at the back of the beach, away from the water line but where the sand is still moist. Tiger beetle larvae are ambush predators that lie in wait at the top of their burrows with their jaws open. They position their head and thorax flush with the ground surface, essentially filling the burrow entrance and disguising their presence (Pearson et al. 2015). When prey is within reach, the larvae anchor themselves to the wall of the burrow by two pairs of hooks on their lower backs and quickly lunge and grab the prey with their mandibles. The struggling prey is then pulled into the bottom of the burrow and eaten. When they are done eating, the larvae carry the indigestible portions of the prey to the top of their burrow and throw them backwards, away from the burrow entrance. The larvae also use their burrow for protection and will retreat into its depths when they sense danger. Larvae primarily use vision to detect danger but may also sense vibrations in the ground created by large predators. Burrow depth is 8-20 cm (3.1-7.9 in.) (Pearson et al. 2015).
Conservation / Management
Many subspecies of Cicindela hirticollis are in decline, with at least one believed to be extinct, and human-caused changes to habitats are widely implicated (Knisley and Fenster 2005). Because the Hairy-necked Tiger Beetle (ssp. rhodensis) is known to occur in Minnesota in only a small area of Lake Superior shoreline, it is extremely vulnerable to development, off-road vehicle use, and foot traffic on the beach. Pollution, shoreline riprap, and other shoreline modifications also threaten the continued existence of this species in Minnesota. The increased frequency of heavy rains and associated flooding that are predicted to result from climate change may affect larval survival (Brust et al. 2005). Loss of genetic diversity due to isolation is also a possible risk factor for this subspecies. As a whole, the Hairy-necked Tiger Beetle seems vulnerable to human disturbance throughout its range and has been in decline in many areas (Graves et al. 1988).
Conservation Efforts in Minnesota
A better understanding of the distribution and abundance of the Rhode Island Hairy-necked Tiger Beetle along Lake Superior is needed. Existing populations need to be protected from excessive recreational beach use with fencing. Experimental creation of sandy habitat adjacent to existing populations should be considered.
References and Additional Information
Casey, T. L. 1916. Further studies in the Cicindelidae. Memoirs on the Coleoptera, VII. The New Era Printing Co., Lancaster 34 pp.
Coffin, B., and L. Pfannmuller, editors. 1988. Minnesota's endangered flora and fauna. University of Minnesota Press, Minneapolis. 473 pp.
Freitag, R. 1999. Catalogue of the tiger beetles of Canada and the United States. NRC Research Press, Ottawa, Ontario, Canada. E-book.
Graves, R. C. 1988. Geographic distribution of the North American tiger beetle Cicindela hirticollis Say. Cicindela 20(1)1-21.
Graves, R. C., M. E. Krejci, and A. C. F. Graves. 1988. Geographic variation in the North American tiger beetle, Cicindela hirticollis Say, with a description of five new subspecies (Coleoptera: Cicindelidae). The Canadian Entomologist 120(7):647-678.
Knisley, C. B., and M. S. Fenster. 2005. Apparent extinction of the tiger beetle, Cicindela hirticollis abrupta (Coleoptera: Carabidae: Cicindelinae). The Coleopterists Bulletin 59(4):451-458.
Leonard, J. G., and R. T. Bell. 1999. Northeastern tiger beetles. A field guide to tiger beetles of New England and Eastern Canada. CRC Press, Boca Raton, Florida. 176 pp.
Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.
Pearson, D. L., C. B. Knisley, D. P. Duran, and C. J. Kazilek. 2015. A field guide to the tiger beetles of the United States and Canada: identification, natural history, and distribution of the Cicindelinae. Second edition. Oxford University Press, New York, New York. 251 pp. + plates.
Steffens, W. P. 2004. Surveys for Tiger Beetles: Cicindela hirticollis rhodensis. Report to Minnesota Department of Natural Resources. 4 pp.
Steffens, W. P. 2009. Update on the status of Cicindela hirticollis rhodensis habitat in Minnesota. Submitted to Minnesota Department of Natural Resources. 6pp.