Accurate identification of garden pests is a fundamental step in implementing effective management strategies. Misidentification can result in wasted effort and continued harm to plants.
The Squash Bug
The squash bug, Anasa tristis, is a common garden pest primarily targeting cucurbit plants like squash, pumpkins, and gourds. Adult squash bugs are flat, elongated insects, 0.5 to 0.75 inches long, and dark grayish-brown. Their abdomens often display alternating orange and brown stripes along the edges. When disturbed, these bugs may emit an unpleasant odor.
Squash bugs feed by inserting their piercing-sucking mouthparts into plant tissue to extract sap. This feeding causes yellow spots on leaves that eventually turn brown and crispy, often leading to wilting and death of leaves and vines. This damage, sometimes called “Anasa wilt,” can stress and kill young plants. Females lay clusters of about 20 oval, bronze eggs on leaf undersides, often in a V-shape. Nymphs hatch in one to two weeks, starting pale green with black legs and gradually turning grayish-brown through five stages.
The Stink Bug
Stink bugs, various species including the brown marmorated stink bug (Halyomorpha halys), are common garden inhabitants. Adults have distinctive shield-shaped bodies, 0.5 to 0.7 inches long, and can be mottled brown, green, or gray. The brown marmorated stink bug has alternating light and dark bands on its antennae and abdomen edges. Like squash bugs, they release a strong, unpleasant odor when threatened, giving them their common name.
Stink bugs use their piercing-sucking mouthparts to feed on a wide array of host plants, including fruits, vegetables, and ornamental plants. Their feeding can cause dimpled, discolored, or corky spots on fruits and vegetables. They can also cause leaf stippling and seed loss. Females lay clusters of 20-30 light green or yellow, barrel-shaped eggs on leaf undersides. Nymphs emerge from these eggs and pass through five developmental stages, often starting with a yellowish or reddish appearance before darkening.
Key Differences
While both extract plant sap, squash bugs and stink bugs have distinct characteristics for identification. A primary visual difference lies in their body shape: squash bugs tend to be more elongated and flattened, resembling a narrow oval, whereas stink bugs have a broader, more pronounced shield-like or triangular body. The color patterns also vary; squash bugs are typically dark gray to brown with potential orange and brown stripes on their abdomen edges, while stink bugs exhibit a wider range of colors including mottled browns, greens, and grays, often with specific banding on their antennae or abdominal margins.
Their host plant preferences and the type of damage they inflict also differ. Squash bugs are highly specialized, primarily feeding on plants within the cucurbit family, such as squash and pumpkins, and their feeding often leads to wilting and plant death due to a toxic saliva. Stink bugs, in contrast, are generalist feeders, targeting a much broader spectrum of plants including various fruits, vegetables, and field crops, and their damage often manifests as cosmetic blemishes or deformities on the produce. Adult squash bugs are known to hide under leaves and plant debris, while stink bugs, especially the brown marmorated species, are notorious for invading homes in the fall to seek overwintering shelter.