The Japanese beetle (Popillia japonica) is a highly destructive insect recognized across North America and Europe as a serious agricultural and garden pest. This invasive species, originally from Japan, was first discovered in the United States in New Jersey in 1916. Understanding what attracts the adult beetle is key to developing effective strategies to manage the damage it inflicts on hundreds of plant species. Attraction is driven by nutritional requirements, which dictate feeding choices, and chemical communication signals, which facilitate mating and aggregation.
Preferred Host Plants and Feeding Habits
The primary attraction for the adult Japanese beetle is the availability of specific host plants, which provide nutrition during its four to six-week feeding period. Adult beetles are generalists, feeding on the foliage, flowers, and fruit of more than 300 plant species. They strongly prefer plants with characteristics like thin leaf tissue and high sugar content.
The beetles cause skeletonizing damage by consuming the soft tissue between the leaf veins, leaving a lace-like network. Favorite hosts include roses, grapes, and linden trees. This feeding behavior is gregarious, causing beetles to aggregate in large numbers on a single host plant.
Chemical Communication Through Pheromones
Beyond the attraction of host plants, chemical signals play a significant role in concentrating Japanese beetle populations. The insects communicate using two main types of chemical cues: sex pheromones and floral volatiles. These scents act as long-distance attractants.
Female Japanese beetles release a volatile sex pheromone to signal readiness to mate, which strongly attracts males. This chemical communication is a primary driver of the localized swarms observed on host plants.
The beetles are also sensitive to general floral volatiles—chemical odors emitted by plants, often non-specific to preferred hosts. These floral scents act as a secondary attractant, drawing both male and female beetles toward potential feeding or mating sites. The combination of the sex pheromone and these floral compounds creates an intense chemical lure that concentrates large numbers of beetles in a small area.
Utilizing Attractants for Management
Knowledge of the beetle’s dual attraction mechanisms—food and chemical signals—is applied directly in control strategies. Commercial Japanese beetle traps utilize a synthetic lure that combines the female sex pheromone and a blend of floral scent compounds.
While effective at capturing beetles, their use is controversial because they attract more beetles into an area than would otherwise be present. Studies show that a trap may attract up to 75% of approaching beetles, but the remainder often land on nearby plants, potentially increasing local damage. For this reason, traps are recommended only for monitoring population levels or as part of a strategic “mass trapping” effort placed far from high-value plants.
Knowledge of host plant preference can also be used for prevention through plant selection and physical exclusion. Homeowners and landscapers can choose to plant resistant species that the beetles find less attractive, avoiding known favorites like roses and linden trees. For high-value plants, physical barriers such as fine-mesh netting or row covers prevent adult beetles from accessing and feeding on the foliage. This method offers protection without the use of chemical controls.