Corn rootworms will gorge on juice from bitter watermelon. Now USDA-ARS scientists are taking advantage of that fact.

They identified the melon ingredient that rootworms desire and developed a process to extract it along with the juice. Then they combined it with a dye that's deadly for rootworms but safe for people and animals.

The lethal dye is D&C Red Dye No. 28, which is approved by FDA for use in drugs and cosmetics.

In field tests, the watermelon-dye combination had killed 85% of adult rootworms three days after application compared with 65 and 70% for two other pesticide-bait combinations.

Corn rootworms cost U.S. farmers an estimated $1 billion annually in lost crops and control measures.

The researchers were looking for an environmentally safe control that would also keep rootworms from developing insecticide resistance.

ARS entomologist Robert Schroder and colleagues have applied for a patent on their formulation.