PestFacts 4 July 2023

Native millipedes

Native millipedes, likely Somethus sp., have been reported in wheat on Yorke Peninsula. They have also been reported in stubble alongside black Portuguese millipedes and slugs on the upper Mid North.

In Australia, there are around 2,000 species of native millipedes, and they are common in mild damp climates.

Unlike the introduced Portuguese millipede, most native millipedes feed on dead plant matter and are unlikely to feed on agricultural crops. They are important for recycling organic matter and generating nutrients in soils, and play a beneficial role in paddocks.

Identification of millipedes

The clearest identification feature that distinguishes black Portuguese millipedes from native species commonly found in southern Australia is that Portuguese millipedes have very smooth, cylindrical bodies with small, smooth rings. In comparison, native millipedes come in a range of colours and most of them have larger rings along their bodies with a rough or ridged appearance. If you see millipedes other than Portuguese millipedes, we would like to hear from you! Please send any photos you have.

Source of reports: Angus Slack, Michael Nash

Slugs and snails

Slug and snail activity continues to be reported in the field, particularly in barley and medic crops – the wet conditions proving particularly favourable for establishment pests. Activity has also been reported near Coonalpyn where small-pointed snails (Theba pisana) were observed feeding on young faba bean stems. However, the primary damage to those crops was probably due to other organisms (possibly slaters), with snails feeding opportunistically on already damaged plant tissue.

Slugs are inundating some crops with up to 30 to 40 slugs per square metre reported in the South East. Reports from both the SE and Yorke Peninsula say that slugs and snails are taking the bait in affected fields. However, slugs are reappearing due to the favourable conditions, and multiple bait applications have been required to get on top of the problem.

Several factors can affect baiting performance and effectiveness, including the chance of snails encountering bait, snail species, movement, weather, and effects relating to bait ingestion (palatability, time of year, snail physiological state). For more information on snail baiting and general snail management, check out the new Nail the Snails practical guide to snail management on the GRDC website.

Source of reports: Steve Richmond (Nutrien, Jamestown), Nigel Myers (Nutrien, Cummins), Adam Hancock (Elders, Naracoorte).

Regional overview of pest observations

Bryobia mite and cowpea aphid

There have been reports in the Mid-Upper North of Bryobia mite (Bryobia sp.) and red-legged earth mite. Cowpea aphid (Aphis craccivora) was observed in vetch, although not in great numbers and is likely to dissipate with winter conditions despite good crop growth.

Lucerne flea

Agronomists are reporting that lucerne flea (Sminthurus viridis) is much more prevalent than usual in pastures across the southern Fleurieu, lower and upper Eyre Peninsula, and in the South East, with the most serious infestations seen in paddocks adjacent to timbered gullies or swamps. Serious patchy damage has also been observed in perennial grass and subclover pastures, lucerne and to a lesser extent in forage cereal crops. At this stage large infestations are assumed to be caused by damp late spring conditions, carryover pasture residues through summer, early and persistent opening rains, and the mild weather up to mid-May.

Pasture tunnel moth

Pasture tunnel moth (Philabota productella) larvae were found in two late-sown forage cereal crops at Parawa. There was little crop damage evident but patches with high densities of larvae displayed silk-lined tunnels with raised 'chimneys'.

Redlegged earth mite

Redlegged earth mites (RLEM) have been active throughout the Mid-Upper North and Eyre Peninsula, and across the Fleurieu for the last 6 to 7 weeks. The most serious feeding damage is on newly-sown pastures, with established regenerating pastures seemingly more robust due to excellent early-season conditions. Growers should refer to the Redlegged earth mite best management practice guide from GRDC.

Black-headed cockchafer and red-headed cockchafer

There have been serious black-headed cockchafer (Acrossidius tasmaniae) infestations in several over-sown and fully reseeded pastures at Pages Flat, Hindmarsh Tiers and Parawa.

Red-headed cockchafer (Adoryphorus coulonii) has been an issue in fields on the eastern side of Naracoorte.

Diamondback moth

Diamondback moth (Plutella xylostella) was noticed in sprayed canola on lower Eyre Peninsula but dissipated after heavy rains in the area.

Source of reports: Greg Mitchell (FP Ag), Steve Richmond (Nutrien, Jamestown), Nigel Myers (Nutrien, Cummins), Adam Hancock (Elders, Naracoorte).