The Brown Marmorated Stink Bug (BMSB) is a pervasive pest that often enters homes seeking shelter. These shield-shaped insects, native to Asia, are now widely established across North America, presenting challenges for both homeowners and agriculture. Stink bugs do lay eggs as a regular part of their life cycle, leading to the next generation of pests. While the presence of adults indoors is a nuisance, finding and eliminating their eggs is an important step in population control.
Identifying Stink Bug Eggs
Stink bug eggs are distinctly small and are deposited in organized clusters, which makes them easier to spot. Each egg mass typically contains between 20 and 30 eggs, all securely attached side-by-side to a surface. They possess a characteristic barrel-shape and measure approximately 1 millimeter in diameter.
When freshly laid, the eggs exhibit a pale color, ranging from light green to white or cream, and they have a firm texture. As the embryo develops, the color may change slightly. In some cases, the eyes of the developing nymph become visible as two distinct red dots through the translucent shell. Recognizing these masses on foliage is the first step toward effective pest management.
Seasonal Egg Laying and Placement
The reproductive phase for the Brown Marmorated Stink Bug begins in the late spring after adults emerge from their overwintering sites, with egg-laying occurring consistently through the summer months. Female stink bugs can produce multiple clutches of eggs during this period, contributing to rapid population growth. The female uses a strong adhesive to attach the cluster of eggs firmly to a chosen surface.
Preferred locations for egg deposition are the undersides of leaves, particularly those of host plants the nymphs will feed on immediately after hatching. Laying eggs on the leaf’s underside provides protection from predators and environmental exposure. While vegetation is the most common site, masses can sometimes be found on other flat surfaces near food sources, such as screens, garden furniture, or the exterior walls of structures.
From Egg to Nymph Early Life Cycle
Once laid, the eggs begin a short incubation period that lasts approximately four to seven days, depending on the ambient temperature and humidity. Upon completion of this stage, the eggs hatch, releasing the first stage of the juvenile insect, known as the first instar nymph. These newly hatched nymphs are quite small, measuring only about 2.4 millimeters in length, and initially possess a striking coloration.
The first instar nymphs are frequently described as having a black head and thorax with an abdomen that is reddish-orange or yellowish-red. They often remain clustered immediately around the empty egg mass for a short time before beginning to disperse and feed. The nymphs undergo a total of five molts, gradually increasing in size and changing color, before finally reaching the winged adult stage.
Management and Removal of Egg Masses
Targeting the egg stage is an important strategy because the egg mass is stationary and cannot disperse like the adult insects. The most straightforward and effective control method for a homeowner is the physical removal and destruction of any egg masses found. This manual intervention prevents the entire clutch of eggs from hatching into destructive nymphs.
To remove them, scrape the cluster off the leaf or surface using a gloved hand, a piece of tape, or a stiff brush. The removed egg masses should then be crushed or submerged in a container of soapy water to ensure they are destroyed. Preventing adult females from accessing egg-laying sites near the home involves sealing gaps and cracks in window frames and door sweeps during the spring and summer. Manual removal is the preferred direct method, as chemical treatments are often less effective against the egg stage itself.