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College of Food, Agricultural, and Environmental Sciences


Fall Ideal Time to Sample for Slugs

October 31, 2006

WOOSTER, Ohio -- For no-till growers with a history of slug problems, now is the time to sample fields to assess spring populations.


Ron Hammond, an Ohio State University research entomologist with the Ohio Agricultural Research and Development Center, said that growers should scout fields and set up traps once harvest is completed.

"Sampling is easiest following harvest," said Hammond, who also holds a partial Ohio State University Extension appointment. "Fall slug sampling gives growers an idea of how severe slug populations may be in the spring and lends to appropriate management decisions."

Slugs are pests that can make an easy meal of young corn and soybean plants in the spring, impacting plant performance and reducing yields. Adult gray garden slugs are commonly found in the fall, looking for places to lay eggs or to overwinter and lay eggs in the spring. Juvenile slugs that hatch out in the spring are the most destructive, especially in no-till fields. No-till fields tend to carry the highest slug populations because the residue provides a shelter for the adults, the eggs and the juveniles.

Hammond said that by setting traps following crop harvest and assessing slug populations over a period of several weeks, growers can identify which fields might need special attention in the spring. There are a number of ways to accomplish this.

• Place wood boards or roofing shingles on the ground and count the number of slugs found underneath them. "It is best to count the slugs in the morning," said Hammond. "Ten traps in a field would be a good number to use."

• Visit fields in the evening before dusk or early in the morning during periods of heavy dew or fog for slugs crawling on plant residue.

• Scout underneath leaves of larger weeds for adult slugs.

• Fill cups of beer and place them in holes throughout the field. The yeast and fermentation process of the beer tends to attract slugs. "If you don't want to use beer, you can achieve the same thing by mixing yeast, sugar and water," said Hammond.

Although no slug thresholds are available, fields with large numbers should be monitored more closely in the spring and earmarked first for early planting to allow crops to outgrow any slug feeding.

"Fields with low numbers, while still needing sampling next spring, can be a lower priority," said Hammond.

In addition to scouting, growers may also consider strip-till in the fall. Hammond said that although no evidence exists to suggest strip tillage reduces slug populations, the practice help plants germinate more quickly and grow faster in the spring.

To learn more about slug management, log on to


Candace Pollock
Ron Hammond