Flowers are rich sources of energy and nutrients, making them frequent targets for a variety of insects. This interaction, known as floral herbivory, spans a wide spectrum, from beneficial pollination to destructive feeding that compromises the plant’s ability to reproduce. Flowers contain high-value biological resources like protein-rich pollen and carbohydrate-heavy nectar, which attract insects seeking a concentrated, readily available food source. Understanding the specific feeding mechanism and the visible damage left behind is the best way to identify the culprit and protect blooms.
Insects That Consume Solid Flower Structure
Some insects possess chewing mouthparts designed to physically bite and tear away at the flower’s solid tissues, including petals, buds, and reproductive organs. This type of damage is immediately structural and often leaves behind clear, ragged physical evidence. The larval stage of moths and butterflies, known as caterpillars, are among the most common chewers, consuming entire flower buds or leaving irregular holes in petals and leaves. The destruction caused by caterpillars is often accompanied by frass, which are small, dark green fecal pellets left near the feeding site. Beetles, such as the Japanese beetle and rose chafer, also use powerful mandibles; Japanese beetles cluster on flower petals leaving them with a characteristic tattered or ragged appearance, while rose chafers destroy rose and peony blossoms by feeding on the petals and buds. Earwigs are another group that can cause significant physical damage, often feeding at night and hiding in flower crevices during the day, leaving wide, irregular feeding holes on petals.
Insects That Target Nectar and Pollen
A different group of insects focuses not on the flower’s structure but on its high-energy contents: nectar and pollen. Nectar is a sugary liquid reward meant to entice pollinators, while pollen is a protein source. Bees and flies are primary consumers of these resources, often transferring pollen from flower to flower, which is a mutually beneficial exchange for the plant. However, some insects become resource robbers, taking the reward without aiding in reproduction. Nectar robbers, such as certain species of carpenter bees or short-tongued bumblebees, bypass the flower’s reproductive parts; they pierce a small hole directly into the base of the corolla or calyx to access the nectar, leaving a clean, almost surgical puncture mark on the exterior of the flower. Other insects specialize in consuming pollen, such as pollen beetles, which feed on pollen and can damage flower buds before they open to access the stamens inside, leading to flower buds drying up and dropping prematurely.
Insects That Feed By Sucking Flower Sap
Insects with specialized piercing-sucking mouthparts extract the internal fluids, or sap, from the flower’s delicate tissues. The resulting damage is less about holes and more about subtle, systemic symptoms like discoloration and deformation. Aphids are small, soft-bodied insects that cluster on new growth, inserting their stylets to withdraw sap. This sap extraction starves the flower of nutrients, resulting in distorted, twisted, or stunted blooms and buds. Aphids also excrete a sugary waste product called honeydew, which creates a sticky residue on the flower and can encourage the growth of black sooty mold. Thrips are minute, slender insects that damage flowers by using their rasping mouthparts to scrape the surface cells before sucking the released sap. Thrips damage often manifests as fine silvery or bleached streaking on petals, and heavy feeding can cause buds to fail to open properly or result in severely deformed flowers. Mites, which are arachnids, also use sucking mouthparts, leaving behind tiny yellow or white stippling on petals and surrounding leaves, often accompanied by fine webbing.