Bear whitefly

Systematic position: Tetraleurodes ursorum belongs to the order Hemiptera, family Aleyrodidae. This species is commonly known as the bear whitefly, a term derived from the characteristic appearance of its puparium, which is covered in wax-like filaments resembling fur.

Host plants: This pest primarily infests various species within the Quercus (oak) genus. While it is predominantly observed in forest ecosystems and arboretums, it can also become a significant nuisance in nurseries if host plants are kept in close proximity without adequate quarantine measures.

Biology and lifecycle: The lifecycle follows a hemimetabolous pattern, consisting of eggs, several nymphal instars, and adults. The nymphs, particularly the late-stage puparium, are stationary and feed by inserting their mouthparts into the leaf tissue. Their protective waxy covering makes them difficult to eradicate with simple contact sprays during the immobile life stages.

Nature of damage and harm: Feeding activity causes chlorosis and necrotic spotting on the foliage. The pest secretes honeydew, which creates a sticky surface that often leads to the growth of sooty mold. This fungus blocks sunlight and hinders photosynthesis, ultimately leading to stunted growth and premature leaf drop in severe cases.

Control measures: Effective management requires an Integrated Pest Management (IPM) approach. Systemic insecticides are generally effective when applied to control the active nymphal stages. In large-scale landscapes, encouraging natural predators like lady beetles and parasitic wasps can significantly reduce populations below damaging thresholds.

• Regular monitoring of the underside of leaves for early infestation signs.
• Application of horticultural oils to suppress overwintering stages.
• Sanitation through pruning and removing severely infested branches.