Slugs have plagued crops since ancient times — and they continue to cause billions of dollars in agricultural damage globally each year. In Oregon, slugs inflict an estimated $60–100 million in damage to the grass seed industry alone, according to Rory McDonnell, associate professor in the Department of Crop and Soil Science at Oregon State University and Extension gastropod specialist.
Bread dough offers a nontoxic, inexpensive attractant that can be deployed alone or combined with molluscicides to enhance slug control.
While damage to grass seed is a major concern, slugs and snails also threaten a wide range of crops, including high-value specialty crops like mint. Two non-native species — the European brown garden snail (Cornu aspersum) and the gray field slug (Deroceras reticulatum) — are particularly damaging. These pests feed on hundreds of plant species and cause financial harm to nurseries, farms and home landscapes. In nursery exports, the presence of snails can lead to costly shipment rejections or treatments at ports of entry.
McDonnell leads OSU’s Invertebrate Crop Pest Lab, which focuses on the ecology of invasive slugs and snails and the development of practical, sustainable management solutions. In response to the growing need for alternatives to chemical baits, he and collaborators launched a multi-institution research project to evaluate low-cost attractants for pest gastropods.
The team tested a variety of foods — beer, cucumber, citrus, tomatoes, strawberries, lettuce, hostas and Marmite — but bread dough, a simple mix of flour, water and yeast, emerged as the most effective bait. Slugs and snails consistently chose it over other options. In one field test, more than 18,000 snails were trapped in 48 hours using dough-baited traps.
Bread dough offers a nontoxic, inexpensive attractant that can be deployed alone or combined with molluscicides to enhance slug control. Researchers found the bait remains effective for at least eight days under field conditions, giving it what McDonnell calls “good field life.” It can also be dried and stored, making it a practical solution for pest control in developing countries where pesticide access is limited.
The project demonstrates that bread dough is a scalable, effective and affordable tool for reducing slug and snail damage in agriculture, nurseries and home gardens. It can support attract-and-kill strategies or be used to improve the performance of existing bait systems.
The findings were published in a special issue of Insects dedicated to slug and snail research. Collaborators included researchers from the University of California at Riverside, University of Hawaii at Hilo, U.S. Department of Agriculture, and the Montana Department of Agriculture. The project received funding through the USDA Plant Protection Act Section 7721.
McDonnell’s work helps growers minimize crop losses, reduce pesticide use and protect the quality of Oregon’s nursery and agricultural exports—all while advancing sustainable pest management practices across the globe.
