Transparent Burnet

The Transparent Burnet (Aglaope hyalina) is a moth belonging to the family Zygaenidae. It is easily identified by its unique wings, which are largely transparent due to the lack of scales.

The adult moth features a dark, somewhat hairy body, often with a subtle metallic sheen. Its wingspan typically ranges from 20 to 25 millimeters, making it a relatively small but noticeable insect in orchards.

The larvae, or caterpillars, are known for their distinct coloration, which serves as an aposematic warning to predators. They possess strong mandibles adapted for grazing on leaf tissue.

Pupation occurs within dense, silky cocoons. These cocoons are typically spun in protected areas, such as bark crevices or tree forks, ensuring the safety of the developing pupa.

The species follows a standard metamorphosis cycle: egg, larva, pupa, and adult. It is generally univoltine, meaning it completes one generation per year, with the larva serving as the overwintering stage.

The primary hosts for the Transparent Burnet are various species of the Rosaceae family. The larvae are particularly fond of fruit trees, including apple, pear, cherry, and plum.

During outbreaks, these caterpillars can inflict severe damage to foliage. In heavy infestations, trees may lose a significant portion of their leaves, leading to reduced vitality.

While often found in managed orchards, the pest also utilizes wild Rosaceous shrubs, allowing populations to persist even in the absence of cultivated trees.

Significant defoliation impacts the tree's photosynthetic capacity, which reduces fruit quality, weakens branches, and hinders the formation of fruit buds for the following year.

Young saplings are at high risk, as they have limited leaf area and can suffer stunted growth or total defoliation when attacked by a colony of caterpillars.

Adult moths are typically active during the summer months, with peak flight periods occurring in June and July. This is when mating and egg-laying take place.

Larvae hatch towards the end of summer. They feed actively on leaves for a period before seeking out suitable locations to enter diapause for the winter.

Overwintering occurs as larvae in protected crevices, often under tree bark or in dense branching, where they remain dormant until the following spring.

With the arrival of warmer spring temperatures, the overwintered larvae resume feeding, consuming developing buds and young leaves before reaching their final larval stage.

Pupation begins in late spring or early summer, marking the final stage before the cycle resets with the emergence of the next generation of adults.

The earliest signs of an infestation include the appearance of skeletonized leaves. The larvae consume the softer parts of the leaf, leaving the veins intact, creating a web-like appearance.

As feeding continues, the leaves may be completely consumed, leaving only the midribs and petioles. This characteristic damage is often concentrated in the upper canopy.

The presence of whitish, papery, or silky cocoons on the tree trunks or in branch crotches is a diagnostic sign that the pest has completed its growth cycle.

Reduced vigor and poor seasonal growth are indirect indicators that a tree is under sustained attack by this moth species.

• Skeletonized, transparent-looking foliage.
• Clusters of larvae feeding on the undersides of leaves.
• Visible cocoons tucked into bark ridges or tree forks.

Physical removal is an effective control measure; this includes cleaning the bark of trunks to remove overwintering larvae and pruning infested branches.

Early spring applications of contact insecticides can significantly reduce population density before the larvae begin their intensive spring feeding phase.

Biological control using bacterial-based agents is highly recommended, as these are often selective and minimize impact on non-target beneficial insects in the orchard.

Maintaining tree health through proper fertilization and irrigation helps trees withstand damage and supports quicker recovery after minor defoliation events.

Integrated Pest Management (IPM) practices should be employed, focusing on monitoring population levels and applying targeted treatments only when necessary.