Cactus scale

Taxonomic position: The cactus scale (Diaspis echinocacti) belongs to the order Hemiptera, family Diaspididae. These tiny, sap-sucking insects are specialized parasites that primarily affect cacti and other succulent plants, often becoming a significant problem in both indoor collections and professional greenhouse environments.

Host plants: The pest targets a wide range of Cactaceae. Common victims include species from the genera Opuntia, Echinocactus, Mammillaria, and Cereus. Because of their sedentary nature, infestations can go unnoticed until the scale insects cover a significant portion of the plant's surface.

Biology and life cycle: Adult females possess a rounded, greyish-white shield, while males are smaller and more elongated. The life cycle consists of the egg stage, the mobile 'crawler' stage, and the immobile sessile stage. In favorable conditions, such as warm indoor environments, the scale can complete multiple generations annually, leading to persistent infestations if not controlled early.

Nature of damage: As the insects feed, they insert their mouthparts into the cactus tissue to extract sap. This causes localized yellowing, stunted growth, and unsightly lesions on the epidermis. If left unchecked, heavy infestations can result in the dehydration of the plant, increased susceptibility to secondary fungal diseases, and eventually the death of the cactus.

• Regular inspections of all cacti, checking crevices and beneath existing spines.
• Physical removal of scales using a soft brush dipped in isopropyl alcohol.
• Application of systemic insecticides that are absorbed by the plant tissues.
• Strict quarantine procedures for all newly acquired plants before introducing them to the main collection.
• Maintaining optimal plant health to enhance natural resistance against pest pressure.