A pest of fruit vegetables, leafy vegetables, and fruit trees
Variable Plant Bug
▶Order/Family: Hemiptera (True Bugs) / Miridae (Plant Bugs)
▶Scientific Name: Adelphocoris suturalis (Jakovlev)
▶Size: Body length 7.5–9 mm
▶Host Plants: Various crops and weeds, including mugwort, barley,
edible amaranth, and soybeans.
▶Distribution: Korea, Japan, China, Russia, and other regions.
The variable plant bug (Adelphocoris suturalis) has a body length of 7.5 to 9 mm. Its body is pale yellowish-green, marked with dark brown patterns, and covered in fine hairs. True to its name, its coloration is highly diverse, displaying a continuous spectrum of variation. The insect features large, black compound eyes and lacks a longitudinal groove on the top of its head (vertex). Its antennae are long, with the terminal two segments being notably dark; the second segment is the longest, followed by the third. Additionally, its tibiae (lower legs) are covered with numerous needle-like spines.
Color variation among individual bugs is extreme. If you were to compare specimens with patterns at the absolute opposite ends of the spectrum, you might easily mistake them for entirely different species. However, when examining a large population, it becomes clear that these differences are simply a continuous natural variation. Specifically, one can trace a clear transitional path: starting from individuals with just two tiny black spots in the center of the pronotum (the plate covering the thorax), the patterns gradually expand until two additional spots appear on the front margin, resulting in bugs with four distinct spots.
This pest feeds on the new shoots and fruits of a wide variety of plants, including mugwort, crown daisy, barley, rice, edible amaranth, soybeans, and sunflowers. This feeding behavior is believed to contribute significantly to the formation of pecky rice (discolored, spotted grains) and deformed fruits. Because these are the hallmark symptoms of damage caused by many types of plant bugs within the Miridae family, it remains an important area requiring extensive future research.
FAQ:
Q: What is the variable plant bug, and what kind of agricultural damage does it cause?
A: The variable plant bug is a true bug pest known for its highly variable physical patterns; it feeds on the young shoots and fruits of diverse crops like barley, rice, and soybeans, which often results in discolored grains and deformed produce.