The larvae of the Box Tree Moth (Cydalima perspectalis) feed voraciously on the foliage of boxwood plants and, in severe cases, also strip the bark from stems and branches. This dual feeding behavior can lead to extensive drying, defoliation, and eventually the death of the plant. Infestation typically begins in the lower parts of the shrub, where older leaves—often richer in natural toxins—are targeted first. Visible symptoms of damage include chewed leaf edges, skeletonized leaves where only the veins remain, and a general thinning of the canopy. As larvae develop, they leave behind silken webbing that binds together twigs and leaves, often accompanied by frass (insect droppings) and shed black head capsules of various sizes—clear signs of ongoing larval activity. These symptoms make infestations relatively easy to identify, but swift intervention is necessary to prevent permanent damage to the plant.

The female Box Tree Moth (Cydalima perspectalis) lays clusters of 5 to 20 eggs encased in a translucent, gelatinous mass on the leaves of boxwood plants. The larvae are light green with distinctive black stripes, white dots, fine hairs, and a black head. Depending on factors such as day length, temperature, and food availability, the larvae go through five to seven developmental stages, or instars.

Pupation occurs hidden between leaves, making the pupae difficult to spot. Initially, the pupae are green with brown longitudinal stripes, gradually changing to light brown with darker patterns as they mature.

Adult Box Tree Moths come in two color variants. The most common form is mostly iridescent white, featuring a dark brown band along the wing edges and a distinctive white spot on the forewings. The less common variant is mostly light brown but also displays the white forewing spot. These adults are strong fliers and typically rest on box trees or nearby vegetation during the day. The species undergoes an obligate diapause lasting six to eight weeks, entering this dormant stage during the fourth or fifth larval instar depending on day length.

Preventing infestations of the Box Tree Moth (Cydalima perspectalis) is extremely challenging due to the moth’s discreet egg-laying behavior, the cryptic nature of its larvae and pupae, and its strong flying ability. Eggs are laid on the undersides of leaves in translucent clusters, making early detection difficult. Once hatched, larvae feed and hide within the dense foliage, often remaining unnoticed until significant damage has already occurred. Pupae are well concealed between leaves, wrapped in boxwood coloring, further complicating monitoring and control efforts.

Because of these characteristics, traditional preventative measures such as visual inspection, sanitation, or exclusion have limited success. One of the few effective prevention strategies involves the use of pheromone traps, which release synthetic sex pheromones to attract and trap male moths. This disrupts the mating cycle by reducing the chances of females being fertilized, thereby limiting population growth. While pheromone trapping alone may not completely eliminate an infestation, it is currently one of the most practical and proactive tools available for suppressing and monitoring Box Tree Moth populations before serious damage occurs.

Biological control of the Box Tree Moth (Cydalima perspectalis) can be effectively supported through the use of Capsanem, a biological product containing the entomopathogenic nematode Steinernema carpocapsae. These microscopic nematodes are natural insect parasites that actively seek out and infect caterpillars and pupae of the box tree moth.

When applied as a foliar spray, Capsanem nematodes penetrate the larvae through natural body openings. Once inside, they release symbiotic bacteria that kill the host within 24 to 72 hours. The nematodes then reproduce inside the dead insect, continuing their life cycle and potentially infecting additional larvae. This makes them a powerful and residue-free solution for reducing active populations.

For best results, Capsanem should be applied in the early morning or late evening when temperatures are moderate and humidity is high, conditions that promote nematode survival and mobility. Applications should target the foliage and inner parts of the plant where larvae feed and pupate, especially in areas showing signs of webbing and frass.

Used as part of an integrated pest management (IPM) program—potentially alongside pheromone traps for mating disruption—Capsanem offers a sustainable and environmentally friendly method of controlling Box Tree Moth populations while protecting ornamental boxwood plants.