Why do gardeners need to identify garden bugs before taking action against them? When should we leave them to their natural activities?
A look at assassin bugs, leaf footed bugs, squash bugs and stink bugs points up good reasons to know your bug before you choose its fate.
Stink bugs and leaf footed bugs are active from May through the fall. We can expect two generations per year with the population peaking in late summer into early fall.
Both bugs pierce and then suck plant juices from vegetables, flowers and fruits. Their most severe damage results from feeding on fruiting structures. As the bugs puncture fruits they inject a toxin-like substance into the tissue. Injury includes pitting, discoloration and deformity. Moreover, puncturing the fruit sometimes allows pathogens to enter and cause rot.
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Stink bugs are so named because they emit a foul smelling liquid when frightened. They feed on not only plants but other insects, too. Both the common green and the brown stinkbugs have broad shield-shaped bodies. The green adults evolve from black nymphs into green with orange and black markings before becoming all green with a narrow yellow perimeter. The adult brown species develop from pale green nymphs. Generally, the green stink bugs eat plants and the brown ones prey on insects.
Leaf footed bugs get their name from the flattened leaf-like flare on the lower portion of their back legs. Adults are brown with a slightly elongated-shield shaped body. They have a cream stripe across their body midway between their head and the tip of their abdomen.
Identify leaf footed nymphs their red-orange bodies and long black legs. They are structurally similar to adults but smaller and have underdeveloped wings.
Squash bugs are devastating and specific to cucurbits (cucumbers, melons, pumpkins and squash). Commonly confused with stink bugs, they also emit foul odor when frightened. Adults are more than ½ in. long. They are brown or gray and shield-shaped, a bit more elongated than stink bugs.
Check daily for oval bronze-brown egg clusters on underside of cucurbit leaves. Young nymphs, which are grey with black legs, are often found clustered together feeding, whereas later instar stages become solitary feeders. Squash bugs are highly damaging to plants and fruit.
It is critical to find and destroy squash bug eggs and nymphs early before they kill cucurbits. Later the adult bugs are tougher to eradicate. Spray the underside of plants’ leaves with insecticidal soap. Handpick and remove nymphs and adults. Drop them into soapy water or knock them on onto the ground and crush them. Trap them under a board at night--adults and nymphs will congregate under it. Smash them in the morning.
Assassin bugs do not feed on plants, but hunt for insects on plants. They catch their prey and hold it down with their front legs. They then inject toxin and stab it to death with their beak-like mouth. The toxin liquefies the quarry’s organs so the assassin bug can then suck out the victim’s bodily fluids. The process sounds brutal, but assassin bugs are good bugs. They eat aphids, flies, leafhoppers, asparagus beetle eggs and larvae, as well as small and medium sized caterpillars.
The assassin bug’s life cycle consists of three stages, egg, nymph and adult. It is fairly easy to tell an adult assassin bug apart from the above listed bugs. However, it is difficult to distinguish between a leaf footed bug nymph and an assassin bug nymph. Both have orange-red bodies and long black legs. Their abdomens curve upward at the sides which makes them look as if their backend is elevated. You will find leaf footed bug nymphs in clusters, however, while assassin bugs are solo hunters.
As an assassin bug matures black markings develop on its head and body. As an adult its body becomes more elongated than those of the three above listed shield-shaped plant eaters. Look for a red-orange perimeter around the assassin bug’s body. The similarity lies in the nymph stage more so than the adult.
Be aware that assassin bugs, also known as the kissing bug, can inflict a painful bite on humans. Leave them alone and they should not bother you.
Get to know these bugs to learn whether, when and why to control them.
Reach Debbie Menchek, a Clemson Master Gardener, at firstname.lastname@example.org.