Common Gray

The Common Gray (Boarmia pampinaria, often referred to as Anavitrinelia pampinaria) is a moth species in the family Geometridae. Adults are characterized by a wingspan of approximately 30-40 mm, featuring a mottled gray and brown pattern that provides excellent camouflage against tree bark.

The larvae, known as loopers, move in a distinct looping motion due to the reduction of prolegs in the middle of their bodies. They typically grow up to 35-40 mm in length, and their coloration is highly variable, ranging from green to brown to match the twigs of their host plants.

Pupation usually occurs in the soil or within leaf litter at the base of host plants. The pupa is brown, smooth, and is the stage in which the insect overwinters, making it a target for soil-based control methods during the dormant season.

This moth undergoes a complete life cycle comprising egg, larva, pupa, and adult stages. Depending on the geographical region, there may be one or two generations per year, with adult moths emerging in the spring to mate and lay eggs on foliage or twigs.

Monitoring is typically conducted using light traps or pheromone lures to detect the presence of adults. Scouting for young larvae on leaves during the early spring is crucial for timely identification, as early-stage caterpillars are easier to manage than mature ones.

The Common Gray is a polyphagous pest, meaning it feeds on a wide range of host plants. It is commonly found attacking fruit trees such as apple, pear, and plum, as well as several berry crops like currants and gooseberries, causing significant economic damage.

Beyond fruit crops, the larvae are known to infest various forest trees including maple, oak, and willow. This ability to thrive on non-crop hosts allows populations to build up in surrounding wooded areas before moving into orchards and gardens.

The larvae are foliage feeders, consuming leaf tissue and leaving behind only the veins (skeletonization). Intense feeding can lead to severe defoliation, which reduces the tree's ability to photosynthesize and store energy for the subsequent year's growth.

In addition to foliage damage, caterpillars may feed on blossoms and developing fruitlets. This direct feeding results in fruit drop, disfigurement, and overall yield loss, which is particularly devastating for commercial orchard operations.

Repeated defoliation by these loopers weakens the host plant, making it more susceptible to environmental stressors, such as drought or frost, and secondary infections from pathogens that exploit damaged tissue.

Cultural control practices, such as deep cultivation or tilling of the soil around the base of trees in the fall, can help destroy overwintering pupae and significantly reduce the emergence of the next generation of adults.

Banding the trunks of trees with sticky traps or pheromone-infused barriers can prevent the movement of caterpillars up the tree. This is an effective non-chemical method that captures larvae and allows for easy mechanical removal.

Biological control, specifically the use of Bacillus thuringiensis (Bt), is highly effective against the larval stages. Bt is a selective microbial pesticide that targets loopers specifically while leaving beneficial predators and pollinators unharmed.

Chemical control should be applied based on economic thresholds determined by monitoring. Using selective insecticides that target lepidopteran pests helps maintain the balance of beneficial insects in the orchard while mitigating the impact of the infestation.

Maintaining orchard sanitation by removing overgrown brush and weeds around the perimeter is an important preventative step. This reduces the number of suitable egg-laying sites and makes the environment less attractive to incoming moth populations.