Stinkbug Nymph – Euschistus tristigmus luridus

Stinkbug Nymph – Euschistus tristigmus luridus
Family Pentatomidae
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Live nymph stink bugs photographed at Forest County, Pennsylvania, USA

I found this energetic stinkbug nymph on a warm day in August, in the Allegheny National Forest near Merianville, Pennsylvania, USA. This is one beautiful bug, and is illustrative of the truly marvelous wonders to be found in nature.

Like all true bugs, this insect sucks, literally, injecting enzymes which break down plant tissues and cell walls, then vacuuming up the resulting nutritional slurry. Because stinkbugs feed on a wide variety of plants, including milk thistle, echinacea, asparagus, oats, mint and goldenrod, they are found in a wide variety of habitats.

They are active from May until September here in the American midwest. These colorful bugs are by far the most numerous stink bugs here in the western suburbs of Chicago. I find infestations of hundreds of individuals in very small areas of forest.

Stink Bugs are shield-shaped bugs with 5-segmented antennae; large, triangular scutellum; head relatively small and often "tucked into" a concavity in anterior margin of pronotum; ocelli present.

Body is divided into 5 sections: pronotum, scutellum, two basal leathery portions of hemelytra [one on each side of the scutellum], and two apical membranous portions of hemelytra that completely overlap and act like a single section [1].

Stink bugs feed on developing seed of many hosts including trees, shrubs, vines, weeds and many cultivated crops. They may also feed on the stems and foliage when seed are not present. Both nymph and adult stink bugs pierce plants with their needlelike mouthparts and suck sap from pods, buds, blossoms and seeds.

Stinkbug characteristics: triangular scutellum, ocelli, compound eyes and flying wings.

This dusky stinkbug nymph has not yet developed flying wings
Stink bugs get their common name from the foul-smelling fluids they exude when disturbed. Both adults and nymphs have large glands that discharge underneath the body.  Stinkbugs are shy, I can tell you – and they will fly off very quickly if you get in their face.

Several species of insects that feed on peaches and other fruits early in the growing season cause a gnarling and distortion of the fruits called catfacing. Plant bugs and stink bugs, called catfacing insects, are largely responsible for this type of injury. They suck the sap from the fruit. If the peaches do not fall as a result of this attack, fruit development is inhibited in the area of the punctures. The surrounding healthy tissue continues to grow thereby causing a defect resembling a cat’s face.

Tachinid Fly - Trichopoda pennipes
Tachinid fly Trichopoda pennipes lays its eggs on many types of bugs, including leaf-footed and stink.

  1., Stink Bug Nymph – Euschistus tristigmus
  2. Alfred G. Wheeler and Sir T. Richard E. Southwood FRS, Biology of the Plant Bugs
  3. American Museum of Natural History, National Science Foundation and University of New South Wales, Plant Bug Planetary Biodiversity Inventory, Plant Bugs (Miridae)

Order Hemiptera: True Bugs number almost 5,000 species in North America, and 40,000 worldwide. They have mouthparts formed into a beak, adapted for sucking plant juices or the liquefied insides of their animal prey.
Suborder Auchenorrhyncha – Cicadas & Planthoppers
Suborder Sternorrhyncha – Aphids, scales, mealybugs, jumping plant lice