Halyomorpha halys

The brown marmorated stink bug, an insect not previously seen on our continent, has apparently been accidentally introduced into eastern Pennsylvania. It was first collected in September of 1998 in Allentown, but probably arrived several years earlier.

As of April 2007, Halyomorpha halys has been recorded from the following 24 counties:

This true bug in the insect family Pentatomidae is known as an agricultural pest in its native range of China, Japan, Korea and Taiwan. It becomes a nuisance pest both indoors and out when it is attracted to the outside of houses on warm fall days in search of protected, overwintering sites. It occasionally reappears during warmer sunny periods throughout the winter, and again as it emerges in the spring.

Adults are approximately 17 mm long (25 mm = one inch) and are shades of brown on both the upper and lower body surfaces. They are the typical “shield” shape of other stink bugs, almost as wide as they are long. To distinguish them from other stink bugs, look for lighter bands on the antennae and darker bands on the membranous, overlapping part at the rear of the front pair of wings. They have patches of coppery or bluish-metallic colored puntures (small rounded depressions) on the head and pronotum. The name “stink bug” refers to the scent glands located on the dorsal surface of the abdomen and the underside of the thorax.

The eggs are elliptical (1.6 x 1.3 mm), light yellow to yellow-red with minute spines forming fine lines. They are attached, side-by-side, to the underside of leaves in masses of 20 to 30 eggs.

There are five nymphal instars (immature stages). They range in size from the first instar at 2.4 mm to the fifth instar that is 12 mm in length. The eyes are a deep red. The abdomen is a yellowish red in the first instar and progresses to off-white with reddish spots in the fifth instar. Protuberances are found before each of the abdominal scent glands on the dorsal surface. The legs, head and thorax are black. Spines are located on the femur, before each eye, and several on the lateral margins of the thorax.

This species probably has a single generation per year in Pennsylvania. However, in parts of sub-tropical China, records indicate from four to possibly six generations per year. In Japan (and we anticipate in Pennsylvania) adults emerge from overwintering during the beginning of June. They mate and lay eggs from June through August. The eggs hatch into small black and red nymphs that go through five molts during July and August. Adults begin to appear in mid August. In 2001 their flights in search of overwintering sites started in mid September and peaked during the first half of October.

We do not know whether this species will become an agricultural pest in Pennsylvania. In its native range, it feeds on a wide variety of host plants. Fruits attacked include apples, peaches, figs, mulberries, citrus fruits and persimmons. This true bug has also been reported on many ornamental plants, weeds, and soybeans. Feeding on tree fruits such as apple results in a characteristic distortion referred to as “cat facing,” that renders the fruit unmarketable.

Even though these insects do not harm humans and do not reproduce inside structures such as houses, they cause concern when they become active and conspicuous in fall and spring. If many of them are squashed or pulled into a vacuum cleaner, their smell can be quite apparent.

Call today, Schedule today, See results same day! Guaranteed.

Having Problems with this pest? Ask One of the Guys For Advice. Give Our Worker Bee A Click!