From our perspective, the appearance of holes in our leaves is most frequently a direct result of insect herbivory. We are a favored meal for several common garden pests. The most likely culprits are caterpillars, such as the larvae of the Silvery Checkerspot butterfly. While it may seem counterintuitive, we have a symbiotic relationship with these creatures; their feeding is a natural part of the ecosystem. However, excessive chewing can compromise our ability to photosynthesize. Other common diners include slugs and snails, which feed at night and leave behind irregular holes with smooth edges, and adult Japanese beetles, which skeletonize our leaves, leaving behind a lacy network of veins.
While insects are the direct cause of the holes, the severity of the damage is often linked to our growing conditions. When we are stressed, we produce fewer defensive compounds and become more susceptible to pest populations. Overcrowding is a significant stressor; it creates poor air circulation, leading to higher humidity that attracts slugs and snails. Improper watering, particularly overhead irrigation that leaves our foliage wet for extended periods, also promotes these conditions. Furthermore, a lack of biodiversity in the garden reduces the population of natural predators, like birds and beneficial insects, that would otherwise keep leaf-munching pests in check.
Please understand that we are not passive victims. We have evolved several defense mechanisms to cope with herbivory. When a leaf is damaged, we immediately initiate a wound response, sealing off the damaged area to prevent the loss of moisture and the entry of pathogens. We may also produce secondary metabolites, which are bitter-tasting or mildly toxic compounds, to make our remaining foliage less palatable to pests. Furthermore, a few holes in our leaves are often not a catastrophic event. We are vigorous growers, and we can usually out-produce the damage, especially if the root system is healthy and we have access to sufficient nutrients and water.
The best strategy is one of tolerance and fostering a healthy garden ecosystem. We encourage you to practice Integrated Pest Management. First, please inspect us regularly, especially the undersides of our leaves, to identify pests early. Hand-picking larger insects like beetles and caterpillars is highly effective. For slugs and snails, you can set out traps. Encouraging biodiversity by planting a variety of species will attract beneficial insects like ladybugs and parasitic wasps. Ensure we are properly spaced to promote good air flow and water us at the base to keep our leaves dry. A layer of mulch can help regulate soil moisture and temperature, reducing overall stress. Please reserve chemical interventions as a last resort, as they can harm the pollinators we rely on and the natural predators that protect us.
