Juniper webworm

The Juniper webworm (lat. Phalonia rutilana) is a destructive pest belonging to the order Lepidoptera, family Tortricidae. This micro-moth is primarily known for causing significant damage to various species within the Cupressaceae family, particularly affecting juniper trees in both landscape and forestry settings.

The main host plants include various types of juniper (Juniperus spp.). The presence of this pest is often overlooked until visible damage occurs, as the larvae operate within protected environments, effectively hiding from predators and pesticide applications.

The biology of Phalonia rutilana typically involves one generation per year. Larvae overwinter in silken cocoons nestled among needles or under the bark. As spring temperatures rise, the larvae emerge to feed on the tender young growth of the host plant.

Damage is characterized by the browning, yellowing, and subsequent shedding of foliage. Larvae construct silk-webbed nests between needles and stems, which accumulate frass and debris. This feeding behavior not only spoils the visual appeal but also stunts the growth of the shrub.

Effective management and control strategies include:

• Regular inspection of juniper plants during the early spring to identify initial webbed nests.
• Timely application of systemic insecticides during the peak activity of larvae.
• Pruning and removing infested branch tips to physically reduce the pest population.
• Encouraging natural biological control by maintaining a healthy garden ecosystem.