Zucchini flowers are a culinary delicacy and a sign of potential fruit production. When these vibrant yellow blossoms disappear or show damage, it signals that a pest is active. Proper identification is the first step toward protecting the remaining blooms and developing fruit. Culprits range from tiny, chewing insects to larger animals and soft-bodied mollusks, each leaving a distinct calling card.
Insect Pests That Target Zucchini Flowers
Small insects that feed directly on the petals and pollen are the most frequent attackers of zucchini flowers. The most destructive are cucumber beetles, which come in two forms: the striped cucumber beetle (three black stripes on yellow-orange wing covers) and the spotted cucumber beetle (greenish-yellow with 12 black spots). Both species are about a quarter-inch long and feed heavily on soft flower tissue. This feeding creates ragged holes or leads to the complete consumption of the flower, immediately halting fruit development.
Cucumber beetles are particularly damaging because they can transmit bacterial wilt and mosaic viruses from infected plants. Squash bugs are another common pest, appearing as flat, dark gray-brown insects about a half-inch long. They use piercing mouthparts to suck sap, which injects a toxic saliva that causes leaves and stems to wilt and eventually turn black. They will occasionally congregate on the tender flower stems.
Earwigs are also known to feed on zucchini flowers, often leaving behind ragged edges or small oblong holes in the petals. These nocturnal insects hide in dark, moist places during the day and emerge at night to feed. While they are often considered beneficial for eating aphids, a large population can cause noticeable damage to tender blossoms and leaves. Damage from earwigs can sometimes look similar to that of slugs, but a lack of a tell-tale slime trail helps distinguish this insect as the culprit.
Larger Animals and Mollusks
Damage from larger garden visitors is typically more noticeable and may extend beyond the blossoms. Vertebrates like deer and rabbits are attracted to the tender, succulent flowers. Deer damage is characterized by a torn or ragged appearance to the remaining stem or foliage because they lack upper incisors and must tear the plant material. This browsing can occur at heights up to six feet off the ground.
Rabbits feed closer to the ground, and their damage is distinguished by a clean, angled cut, as if the stem was neatly clipped. They often consume the entire flower and stem up to six inches above the soil line. Mollusks, such as slugs and snails, also target zucchini flowers, leaving large, ragged holes in the petals and leaves. The definitive sign of their activity is the silvery, dried slime trail they leave on the plant or surrounding ground.
Targeted Control and Prevention Methods
Effective control requires matching the method to the specific pest’s behavior. For insect pests like cucumber beetles and squash bugs, physical barriers are highly effective. Floating row covers exclude adult beetles, but they must be removed when flowering begins to allow for pollination. Non-chemical approaches include crushing squash bug eggs (bronze clusters found on the underside of leaves) or hand-picking adults and dropping them into soapy water.
For larger animals, robust exclusion methods are the most reliable defense. A fence designed to deter deer should be at least eight feet high, or a double-fence system of two parallel four-foot fences spaced a few feet apart can also be effective. A two-foot-tall fence made of fine mesh, such as chicken wire, is sufficient for rabbits, provided it is buried six inches deep to prevent burrowing. Repellents containing ingredients like rotten eggs or strong scents can be sprayed on plants, but they require reapplication after rain.
Controlling slugs and snails involves eliminating their cool, moist hiding spots and using bait. Iron phosphate pellets are an effective molluscicide considered safer around pets and wildlife than older chemical baits. When ingested, the iron phosphate causes the mollusks to stop feeding, and the product degrades into a soil nutrient. Applying the pellets around the base of the plant in the evening, when pests are most active, provides the best control.