Leaf-footed bugs, primarily species within the genus Leptoglossus, are insects recognized by the flattened, leaf-like expansions on their hind legs. These insects are commonly seen in gardens and agricultural fields across North America. Their presence is a concern because they feed on a wide variety of commercially important plants and ornamental shrubs, causing significant economic losses to numerous crops.
How Leaf-Footed Bugs Consume Food
Leaf-footed bugs are classified as hemipterans, possessing specialized mouthparts designed for liquid feeding. The insect uses a long, needle-like structure called a proboscis or rostrum, which is a tube-like sheath that encases four piercing stylets. The bug inserts these stylets deep into the plant tissue, often targeting developing seeds or fruit pulp.
Once the stylets are in place, the insect injects saliva containing enzymes that predigest the cellular contents. This process liquefies the solid tissue surrounding the feeding site. The insect then sucks up the resulting slurry of digested material and fluids through the stylets. This feeding process extracts internal juices and liquefied solids, distinguishing them from insects that chew external plant tissue. The depth of probing depends on the insect’s size, with nymphs feeding more shallowly than adults.
Preferred Plants and Produce
The diet of Leptoglossus species is highly varied, but the bugs show a strong preference for the reproductive structures of plants, namely fruits, nuts, and seeds. They attack many plants in the Solanaceae family, including fruiting vegetables like tomatoes, peppers, and eggplants. Developing fruit provides a rich source of nutrients, making them a frequent target for both nymphs and adults.
Members of the Cucurbitaceae family are also heavily fed upon, including crops such as squash, melons, and watermelons. Legumes, including peas and beans, are attractive hosts, particularly when the pods are green and the seeds are developing. The bugs also target a wide range of nut and seed crops, where their feeding is especially damaging to the developing kernel.
Important commercial hosts include almonds, pistachios, pecans, and pomegranates. When primary food sources become scarce, especially later in the season, leaf-footed bugs will opportunistically feed on weeds like thistle or move to other crops such as citrus and cotton.
Visible Signs of Feeding Damage
The damage inflicted by leaf-footed bugs results from the combined effect of the physical puncture and the injected digestive enzymes. On tomatoes and other soft fruits, feeding spots initially appear as small, firm, discolored areas. These spots later become sunken and necrotic as the internal tissue collapses. This injury often leads to premature color break on the fruit’s skin, making it unmarketable.
On nuts, the timing of the feeding determines the resulting visual injury and severity of the loss. If feeding occurs early in the season before the shell hardens, the developing kernel may shrivel or completely abort. Gum droplets may appear on the husk of almonds. Later feeding, after the shell has hardened, can still cause damage, resulting in kernel necrosis or the appearance of black spots and wrinkling on the nut meat. Punctures on any fruit or vegetable can also create openings for secondary fungal or bacterial pathogens, which may lead to rotting and crop loss.