Snails on Eyre Peninsula
By Dr Kym Perry, University of Adelaide
19 March 2025
What’s happening with snail populations this year?
Extremely dry conditions over the past year have had one positive effect – snail populations have been kept in check by the weather. It’s likely that the lack of season-breaking rains in 2024 also limited snail breeding, which typically extends from early autumn until at least mid-winter. Similarly, dry conditions in spring and summer 2024/25 will have caused higher than usual levels of mortality, particularly of snails resting in exposed areas and in districts that experienced any heatwaves. Exposure of snails to temperatures of 60 degrees and above kills them instantly, and on a sunny 40 degree day, ground level temperatures can exceed 70 degrees.
On Eyre Peninsula, green Lincoln weed, which is a haven for snails, has been far less prevalent than usual in many areas, reducing refuges for snails to survive in.
Can I take a rest from snail control?
While we are starting from a lower base of snail numbers this year compared to other years, does this mean there is a lesser need for snail control operations?
The short answer is that lower snail numbers is good news for farmers.
However, in areas where pest snails occur, there are always many more snails present than it appears at first glance. This is particularly true for conical snails, which prefer to shelter underneath refuges (rocks, logs, etc) and inside plants (grassy tussocks, Lincoln weeds, etc).
When the weather turns favourable again (i.e., it rains), it’s often surprising how many snails just ‘appear’ seemingly out of nowhere. In reality, they were there all along, just hiding. You have to know where to look! (Figure 1)
We know snails can bounce back quickly when conditions turn around and we have moisture again. So don’t let them off the hook. Hit them when they are down.
Snail control should be easier and more effective this autumn given lower starting numbers.
When to apply snail bait for maximum return on investment
The best timing to start snail baiting is just after snails wake up from summer dormancy, around the end of summer and early autumn.
The baiting ‘sweet spot’ is typically sometime from mid-March to mid-April, depending on local weather and farm conditions. Increased moisture causes them to start moving. This typically occurs overnight on dews and light showers and often goes unnoticed.
These snail movements provide early baiting opportunities that can be very effective. After summer dormancy, snails are extremely hungry. They spend several weeks feeding and maturing their reproductive organs in preparation to start breeding and laying eggs.
This is a great time to bait. At this time, snails move most when ground humidity exceeds about 95%, and this can occur on overnight dews (heading into autumn), or very light rain showers < 2mm. A well-timed baiting when snails are hungry can achieve high levels of control. Kill as many as you can before they start laying eggs.
Guidelines for baiting, including a product selection guide (page 26), are available in section 4 of the GRDC’s Nail the Snails Manual, which is freely downloadable online.
New camera network provides snail movement alerts for farmers
For the first time, growers can receive updates on snail activity in near real time, to help with baiting decisions and timing in autumn 2025.
A network of six ‘experimental’ S3 sentinel snail cameras have been deployed, with three units in SA and three in WA. The three South Australian cameras available so far are located on southern Yorke Peninsula (x2) and at Coulta on Eyre Peninsula (x1, Figure 1).
For regular updates on snail activity, follow me on social media at:
X (Twitter): Dr Kym Perry @x_slimeminister
Instagram: Kym Perry @the_slimeminister
This is part of a GRDC invested project “More effective control of pest snails in Australian grains crops”. The project is led by Dr Kym Perry from University of Adelaide, and in collaboration with SARDI, UniSA, CSIRO, DPIRD WA, and Data Effects.
Author contact details:
Dr Kym Perry, University of Adelaide
m: 0421 788 357 e: kym.perry@adelaide.edu.au
Figure 1: (left) Many small-pointed snails under Brassica stalks, Albany WA, Feb 2025. The S3 snail camera at Coulta SA (right) (Photos: Kym Perry)