Blueberries are a highly sought-after crop, prized for their flavor and nutritional value, making them a target for a wide variety of wildlife and insects. Growing these fruits often results in finding the harvest depleted or the plants damaged. Various creatures view the entire blueberry bush—from the roots and canes to the leaves and developing berries—as an accessible food source. Understanding the specific nature of the damage is the first step toward reclaiming the yield.
Pests Targeting the Fruit
The most visible damage occurs when ripe or ripening fruit disappears just before harvest. Birds are the most common culprits, with species like robins, cedar waxwings, and bluebirds capable of stripping a bush of its berries in a matter of hours. They often consume the entire berry or leave behind small, pecked-open fruit husks still attached to the stem, without damaging the surrounding foliage or branches.
Small mammals, particularly squirrels and chipmunks, also target the fruit for its moisture and sugar content. These rodents steal entire clusters of berries, often carrying them away to consume elsewhere, leaving little direct evidence beyond the sudden loss of the crop. Insect pests also focus on the fruit, with the Spotted Wing Drosophila (SWD) being a major concern. The female fly cuts into intact, ripening berries to lay eggs just under the skin, introducing larvae that feed internally. This causes the fruit to soften, rot, and become unmarketable.
Pests Targeting Foliage and Structure
Damage to the non-fruiting parts of the bush involves chewing insects and large browsing mammals. Japanese beetles are identified by the characteristic skeletonizing they perform on the leaves, consuming the green tissue between the veins while leaving the fibrous network intact. Other caterpillars, such as the yellow-necked caterpillar, can also defoliate branches, sometimes leaving only the leaf veins behind.
Larger mammals like white-tailed deer consume the structural parts of the plant, primarily browsing on new, tender growth and stems up to six feet high. This browsing is particularly damaging to young plants, often resulting in ragged tears on the woody stems. This distinct pattern is caused by the deer’s lack of upper incisor teeth.
Lower-feeding mammals, such as rabbits and voles, focus their damage closer to the ground, especially during the winter when other food sources are scarce. Rabbits clip off small twigs with a clean, angled cut, while voles often gnaw the bark at the base of the cane, which can completely girdle and kill the bush.
How to Identify the Specific Culprit
Identifying the culprit requires keen observation of the specific evidence left behind, as different pests leave distinct signatures.
Stem Damage
When assessing damage to woody stems, the quality of the cut is the most telling sign. A clean, sharp, 45-degree angle indicates a rabbit, whose incisors act like a knife. Conversely, a jagged, frayed, or torn end on a stem is the definitive sign of deer browsing, as they tear the plant material against their lower teeth and dental pad. The height of the damage also points to the culprit; deer typically browse higher, creating a noticeable “browse line,” while rabbits rarely feed more than two feet above the ground or snow line.
Insect and Vole Signs
For insect damage, look for small, pin-sized puncture marks on the skin of ripening fruit, which indicate where the Spotted Wing Drosophila has laid an egg. Evidence of tunneling or “sawdust-like frass” found webbed between multiple green berries points to the Cranberry Fruitworm, which consumes several fruits in succession. The presence of surface tunnels in mulch or grass near the base of the plant, often with small, round droppings, is a clear indication of vole activity.
Effective Protection and Prevention Methods
Exclusion is the most effective method for protecting blueberry bushes from mammals and birds.
Physical Barriers
Overhead netting is recommended for birds, but it must be secured tightly to the ground to prevent small mammals, like chipmunks and squirrels, from gaining access underneath. For larger threats, physical barriers are necessary, such as installing a perimeter fence that is at least six feet high to deter deer from jumping. For smaller ground-level pests, a low, tight fence made of hardware cloth or chicken wire can be buried a few inches into the soil to block rabbits and voles.
Cultural Practices and Repellents
Cultural practices also play a role in prevention. Pruning bushes to create an open canopy helps to deter egg-laying insects like SWD. Regularly removing fallen or damaged fruit from the ground reduces breeding sites for fruit flies and removes a food source that attracts rodents. Repellents, which use scent or taste to discourage feeding, offer short-term relief, but they require consistent reapplication, especially after rain or during periods of new growth.