Species: Brown marmorated stink bug (Halyomorpha halys)
What to look for
- Outline. Shield shaped like other stink bugs, almost as wide as it is long.
- Length. Penn State gives approximately 17 mm (0.66 inch). Maryland gives adults as 14 to 17 mm (about 0.55 to 0.67 inch) and dark mottled brown.
- Antennae, which are the quickest check. Penn State and Maryland both describe alternating light and dark bands on the last antennal segments.
- Wing membrane and abdomen edge. Penn State describes darker bands on the membranous, overlapping part at the rear of the front wings. Maryland notes the exposed edges of the abdomen also carry light and dark banding.
- Surface detail. Penn State describes patches of coppery or bluish metallic punctures, small rounded depressions, on the head and pronotum.
- Nymphs. Penn State gives five nymphal stages from 2.4 mm at the first instar to 12 mm at the fifth, with deep red eyes, a yellowish red abdomen becoming off-white with reddish spots, and black legs, head and thorax.
Where and when
Penn State says adults emerge in spring, from late April to mid-May, mate and lay eggs from May through August, and start looking for overwintering sites from September through October, which is when they are drawn to the outside of houses on warm autumn days. It probably has one generation a year in Pennsylvania, or two after a warm spring and summer. Maryland gives eggs laid June to August.
Does it matter?
Penn State says the brown marmorated stink bug will not reproduce inside a structure or damage it, but that it is a serious pest of fruit and vegetable crops, and that its defensive chemicals can act as an aeroallergen, producing rhinitis or conjunctivitis in sensitive people and dermatitis where a crushed bug contacts skin. If you think you are reacting, ask a doctor. Penn State's remedy is sealing cracks and screens.
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