In this section:
Snail Life Cycle
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Small snails in particular cause problems by contaminating grain at harvest time and as a result of being a similar size to the grain harvested, are often difficult to separate out from the grain. Controlling snail populations throughout the year is vital if grain contamination and crop damage are to be prevented at harvest time. |
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Summer |
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During summer snails rest (aestivate). Snails move up stubble, fence posts and vegetation to rest above ground to avoid water loss during summer. Short periods of summer rain do not trigger breeding. Snail control methods: Stubble Management Rolling, Cabling, Grazing. |
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Autumn |
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Snail activity is triggered by rainfall and cool moist conditions. Snails begin feeding and reproductive organs mature around March and April. Mating starts about 2-3 weeks after the first autumn rain. A 1-2mm shower is enough to trigger snail movement and breeding. Each snail is hermaphrodite (has both male and female reproductive organs) enabling each snail to lay egg clusters after mating. Mating snails are found in pairs with the soles of their feet firmly pressed together. Each snail is inseminated by its partner. Snail control methods: Stubble Management, Burning and Baiting. Early baiting will kill snails before egg laying begins.
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Autumn-Winter-Spring |
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Egg laying begins shortly after mating. Egg clusters are laid in the topsoil from late autumn to early spring. The start of egg laying is determined by soil moisture. Adult snails can be found laying eggs when their foot (the fleshy snail body) is inserted into the top soil forming shallow holes. It is estimated that in the field each snail can lay about 400 eggs a year, which varies with species and seasonal conditions. Eggs are laid in clusters with each cluster consisting of between 20-80 milky white eggs for round snails. Laboratory work shows that conical snails produce less eggs per cluster, often only about half the number found in the egg clusters of round snails. |
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Controlling snails before or soon after egg laying commences is essential. Baiting snails during Autumn rains will greatly reduce egg laying and therefore prevent the problem of juvenile snails contaminating grain harvests later in the year.
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Winter-Spring |
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Eggs hatch after two weeks. Juvenile snails continue to feed and grow through winter and spring. Round snail hatchlings are up to 1.5mm in diameter. Conical snails are smaller, at about 1mm in diameter. Hatchlings emerge from winter to spring and they are the size of a pin-head! |
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