The sand-verbena moth

Figure 1 The sand-verbena moth (Photo: Wendy Gibble, Used under a CreativeCommons CC_BY 2.0 licence)

By Lisa Jørgensen

The sand-verbena moth (Copablepharon fuscum) is, when it comes to looks, a relatively anonymous fellow.  This nocturnal moth, which belongs to the order Lepidoptera (butterflies and moths) and the family Noctuidae, has a wingspan of 3.5-4.0 cm and has only been found in three Canadian sites, all on the coast of southwestern British Columbia, and in a few sites in the northwestern coastal part of Washington, USA.

The moth is heavily dependent on the presence of yellow sand-verbena, as this plant is the only host that it uses for egg laying, and later for the emerging larvae and adult to feed on. The yellow sand-verbena demands sandy, nutrient poor conditions, and though it is present in areas where other plants are dominating, it will only flower at sites where it is the dominant species. The moth has been found to require large patches of yellow sand-verbena to sustain a population, but such patches are difficult to come across because of the habitat requirements of the plant.

Figure 2 Preferred habitat of yellow sand-verbena, here Long Beach Peninsula, WA, US (Photo: Wendy Gibble), Used under a CreativeCommons CC_BY 2.0 licence)

This pickiness in the moth’s choice of host plant is the most probable reason that the sand-verbena moth is considered an endangered species under the SARA (Species at Risk Act), which is the official list of Canadian wildlife at risk. The label ‘endangered’ is put on species that are in risk of extirpation or extinction, meaning that the present populations of an ‘endangered’ species are the last in the wild. We do not know how many individuals of this moth species is left, but we do know that due to plant invasion, the number of sandy patches with yellow sand-verbena is decreasing, as other plants colonize the same habitat, thus keeping down numbers of yellow sand-verbena and keeping them from flowering. When the number or size of available habitats is lowered, the moth populations will naturally experience a decrease. Another reason for the loss of habitat is the proximity of the sandy patches to the shoreline that makes the patches at risk of suffering of erosion or flooding, and the use of dunes for military training that expose the plants to the risk of being trampled down. A more direct threat to the moth than the threat of habitat loss, is the spraying of Btk (Bacillus thuringiensis kurstaki) against the larvae of pest moths, or parasitic flies introduced (i.e. not from the “hood”) for the same cause.

But why should we care about this specific endangered species? It does not play any crucial part in the pollination of yellow sand-verbena, nor is it particularly important in the local food web or to the economy, so what would happen if it we took the laissez-faire approach and did nothing to help this species? It would probably disappear from some patches, and ultimately go extinct, as it has shown poor ability into dispersal on its own. But we can do something, and it may not even cost us a lot of money (that’s a good argument, eh?)! Approaches to help recovery the Canadian populations of sand-verbena moth include the protection of patches dominated by yellow sand-verbena by physically protecting the plants from erosion and trampling by training soldiers, by fencing the area (however temporarily), and the movement of yellow sand-verbena from patches where it has a low abundance (and so no sand-verbena moth population) to patches that are in risk of being dominated by other plants (with a moth population). Also, public outreach to the areas with populations of sand-verbena moth has been initiated, and the existing populations are being monitored. The Ministry of Environment of British Columbia considers the recovery goal of the sand-verbena moth, to maintain the populations at the current locations, to be feasible.

Sources:

SARA (Government of Canada): https://www.registrelep-sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=789 25/11 2015

British Columbia Invertebrates Recovery Team. 2008. Recovery strategy for Sand-verbena Moth (Copablepharon fuscum) in British Columbia. Prepared for the B.C. Ministry of Environment, Victoria, BC. 18 pp.

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