Puritan Tiger Beetle
Tiger beetles are a family of insects that are voracious predators, capturing other invertebrates in a tiger-like manner. The Puritan tiger beetle, brownish bronze above with a metallic blue underside and narrow white lines on each wing, measures under ½ inch in length. This species was Federally listed as threatened throughout its range in 1990.
The Puritan tiger beetle is found in only two regions: along the Chesapeake Bay in Maryland and along the Connecticut River in New England. The Puritan tiger beetle populations in these two regions have probably been separated for thousands of years and have developed significant genetic and ecological differences.
In New England
Only a few small populations, comprising a single metapopulation (a group of spatially separated subpopulations of the same species which interact at some level) of Puritan tiger beetles remain in New England; one along the Connecticut River, near Hadley, Massachusetts and the others near Cromwell, Connecticut. Because of dam-building and modifications of the Connecticut River, only a remnant of the once extensive Puritan tiger beetle populations remains there. In New England, Puritan tiger beetle distribution follows the sand and clay deposits formed by glacial lakes during the last ice age.
In the Chesapeake Bay
The Chesapeake Bay contains only two metapopulations along its shorelines, one on the western shore and one on the eastern shore. In Maryland the Puritan tiger beetle has very specific habitat requirements. The larvae occupy only naturally eroding cliffs, where they live in deep burrows after digging in sandy deposits on non vegetated portions of the bluff face or at the base of the cliffs. They are most abundant at sites where the bluffs are long and high with little or no vegetation and composed in part of yellow or red sandy soil. Erosion results in the loss of some larval beetles, but is necessary to maintain the bare bluff faces they require.
Along the Chesapeake Bay, adult Puritan tiger beetles are first seen in June and July when they emerge to feed and mate along the beach area. After mating the females move up onto the cliffs to deposit their eggs. Newly hatched larvae construct burrows in the cliffs and pass through 3 larval stages before metamorphosing in the adult form. It takes two year for the Puritan tiger beetle to complete its life cycle.
Puritan tiger beetles have disappeared from much of their New England range and have declined in population size and distribution in their Chesapeake Bay range. The remaining Chesapeake Bay populations are highly susceptible to habitat loss or degradation. Shoreline development and bluff stabilization are the most serious threats. Shoreline structures have been found to destroy the larval habitat directly or by promoting vegetation on cliff faces making the cliffs unsuitable for the larvae. Natural threats include flooding, parasites and insect predators.
Conservation and Recovery
Habitat Restoration and Enhancement
A project to restore suitable cliff habitat for Puritan tiger beetles was conducted on the Sassafras River Natural Resources Management Area by Maryland Department of Natural Resources beginning in 2006. This project used herbicides to control vegetation encroaching on the cliffs. The treatment was very successful in eliminating most cliff vegetation and improving habitat conditions for Puritan tiger beetles and 2 years later vegetative cover remained quite low. Puritan tiger beetles numbers at the treatment sites have been closely monitored in the years following treatment. So far, beetle abundance has shown a positive response.
Chesapeake Bay Habitats used by Puritan Tiger Beetles
In 2009, Randolph-Macon College completed a study characterizing habitats supporting Puritan tiger beetles in high or low numbers, within both the Calvert County and Sassafras River metapopulations (Knisley and Fenster 2009). The study determined that geologic formation and vegetative cover control Puritan tiger beetle distribution and abundance. The study also found that degree of soil compaction, average soil grain size, and sorting of soil grains were important habitat parameters. Based on these findings, the study also recommends potential habitat restoration sites.
Translocation of Puritan Tiger Beetles
Limited or short-term success in translocating tiger beetles has been achieved using larval beetles, but not adults, in both New England and the Chesapeake Bay area. Recent studies with the northeastern beach tiger beetle, a closely related rare tiger beetle, indicates that translocation is possible and may have value for the recovery of the Puritan tiger beetle. To date, the attempted translocations of Puritan tiger beetles to currently unoccupied habitats have not led to long-term establishment of a significant beetle population. Nonetheless, the Service believes that additional translocations, using existing and new techniques, should be pursued in appropriate habitats to support the recovery of these species.
Puritan Tiger beetle Propagation
Successful propagation of Puritan tiger beetles has been developed through research at the University of Massachusetts and Randolph Macon College. Translocation of propagated Puritan tiger beetle larvae has been attempted at cliffs along the Chesapeake Bay, but was not successful, possibly due to vandalism at the translocation site. The Service intends to continue work with translocating propagated Puritan tiger beetle larvae, particularly along the Connecticut River in New England, where unoccupied sites with good potential habitat have been identified. Although past efforts have failed to identify suitable sites for translocation in Maryland, we are now intensively looking for potential new sites on the shores of the Chesapeake Bay.
Do you want to see the research?
Visit the Tiger Beetle Reports and Publications page for a selection of scientific papers and studies.