Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

Loxostege sp. ‘salt pan’ (of Stringer et al. 2012)

Loxostege sp. ‘salt pan’ (of Stringer et al. 2012)


Current DoC threat status

Relict

Recognition / similar species

Easily recognised by its plain grey colouring with more or less indistinct forewing pattern of black crosslines; the costa is slightly concave beyond the middle of the wing. The behaviour is also characteristic: it is diurnal and flies low to the ground on the barest ground in salt pans and other bare areas.
No similar species.

Known distribution and abundance

Discovered in 1985 in the southern end of the Mackenzie Basin, this species is now known from 19 sites in the interior of the South Island in Central Otago, Waitaki Valley and Mackenzie Basin (CO, DN, SC and MK). Many of these sites are extremely small. They range in altitude from 200-500m.

Habitat

The species occupies very small sites (0.04 – 1.0 ha) that are very vulnerable to disturbance and modification. These are mainly bare salty ground of saltpans, but several populations have been found in other types of bare silty ground such as by lakes or at the base of hill slopes.

Host-plant and biology of early stages

The fat wriggly larvae are found in silk webbing amongst the hostplant foliage on the margins of bare areas on silty or salty soils. The hostplant on saltpans is Atriplex buchananii (Chenopodiaceae) while the similarly grey-coloured Convolvulus verecundus (Convolvulaceae) is utilised in one silty area by Lake Tekapo. The larvae have been found and reared to adults and notes made.

Flight period (months of year) and behaviour of adult

One generation is passed annually but this is inconclusive. Based on data from 57 observations of adults in the field, it is likely that adults have a protracted emergence from mid September to early April, with peak emergence in October when 60% of adults have been recorded. Few adults are seen after late January. Additionally pupae in mid summer took over two months to hatch lending evidence to only one generation being passed each year.

Adults fly on sunny days and are very active and wary. They fly close to the ground and often settle on the barest ground.

Potential monitoring technique(s)

A standardised walk-through counting method in saltpan habitat would work well. October and November would be the best time of year to perform this monitoring and air temperature and bright sunshine must be considered.

Threats

The species is known from 12 saltpan areas, nine of which now have some form of protection, and seven other sites. This species requires security of its mainly saltpan habitat, and monitoring to ensure that the hostplant survives in abundance there. Other known sites are mostly under Pastoral Lease tenure or are private land. At those sites it is threatened by ongoing degradation of these lands and changes in farming practices, i.e. intensification and subsequent loss of more natural habitats.

Brian Patrick