Flat-backed millipede

Systematic position: Polydesmus complanatus belongs to the class Diplopoda, order Polydesmida, family Polydesmidae. These soil-dwelling invertebrates are known for their preference for dark, damp environments rich in decomposing organic matter, which often brings them into contact with agricultural areas.

Crops: The pest poses a significant threat to various vegetable, root, and ornamental crops. It is particularly damaging to carrots, potatoes, beets, and young seedlings of cucumbers and cabbages. Damage is often observed both in greenhouses and open fields where soil moisture levels remain consistently high.

Biology and life cycle: The life cycle of these millipedes is highly dependent on environmental humidity. Eggs are deposited in small, constructed chambers made of soil and excrement. As they develop through multiple molting stages, they progressively add segments to their bodies. Given sufficient moisture and organic food sources, they can reproduce throughout the growing season.

Nature of damage: Polydesmus complanatus feeds by gnawing on the underground parts of plants. They create deep pits, lesions, and irregular cavities in tubers and roots. These feeding wounds not only physically weaken the plant but also serve as entry points for pathogenic bacteria and fungi, frequently leading to secondary decay and total crop loss.

• Practice proper crop rotation.
• Remove plant debris regularly.
• Manage soil moisture levels effectively.
• Apply authorized soil insecticides.
• Utilize deep autumn plowing to disturb habitats.

Control measures: Effective management relies on improving soil drainage and ensuring the prompt removal of decaying plant residues where millipedes thrive. In greenhouse conditions, steam sterilization or soil freezing can significantly reduce populations. When infestations reach economic thresholds, application of granular insecticides specific to soil-dwelling pests is recommended to minimize damage to vulnerable crops.