Hop flea beetle

The hop flea beetle (lat. Psylliodes attenuata) belongs to the Coleoptera order and the Chrysomelidae family. This small, jumping beetle is a specialized pest that poses a serious threat to hemp cultivation and several other agricultural crops globally.

While the hemp plant is its primary food source, the beetle is polyphagous under certain conditions. It can cause economic damage to crops such as fodder beet, winter rapeseed, cabbage, sunflower, winter barley, alfalfa, and apple trees, especially when primary hosts are unavailable or populations reach high densities.

The biology of this pest involves one generation per year. Adult beetles overwinter in plant debris, hedges, or the top layer of soil. In early spring, as temperatures rise, they emerge to feed on the cotyledons and first true leaves of young seedlings. Females subsequently lay eggs in the soil near the roots, and the emerging larvae feed on the roots, which can cause significant stunted growth.

The damage is primarily characterized by numerous small, circular, or irregular holes in the foliage, often referred to as shot-holing. This intense feeding pattern reduces the leaf area, disrupts photosynthesis, and makes the plant highly susceptible to secondary diseases. Severe infestations during the seedling stage can lead to total crop failure.

Effective management strategies combine cultural and chemical practices. Key cultural methods include practicing crop rotation, maintaining weed-free fields to remove alternative hosts, and utilizing deep plowing to disturb overwintering sites. Chemical control involves the application of systemic or contact insecticides during the critical early growth stages when the threat of beetle feeding is at its peak.