Pest Problems

How to Identify Shield Bugs and Prevent Them From Entering Your Home

Each year, with the arrival of bad weather, our homes are being charged by all kinds of pests. Every one of them wants to shelter in with you, enjoying the abundance of food and warmth. One of these pests is the notorious stink bug, or shield bug, as it is largely popular here in the UK.

The name “Stink bug” originates from this insect’s ability to release an odour through a special gland on its belly when disturbed or crushed. Such defence mechanisms are used by lots of other insects. In the UK, this particular insect is more commonly known as a Shield bug, thanks to its shape.

If you:

  • Have lots of indoor plants;
  • Have a basement;
  • Often spot shieldbugs inside.

Then this post might be just what you need! Read on to find out more about these little stinkers and how you can keep them in check.

What are shield/stink bugs?

Those insects get to around 2cm long and roughly the same in width. They have six legs and a pair of antennae. Adults have wings and are good flyers. They are not beetles, although they may look like them. These insects belong to the “True Bugs” family, characterised by piercing-sucking mouthparts and a triangle shape on their backs, that comes from the shape and structure of their wings.

The younglings are called nymphs and have around five stages of growth before turning into adults, not including the egg and larvae stages of their life cycle.

Shield bug identification

You can spot mainly two species in the UK. The brown marmorated stink bug (Halyomorpha halys), which is an invasive species from Asia, and the local green shield bug (Palomena prasina). As you can deduct from their names, both species are easily distinguishable by their colour.

The brown marmorated stink bug carries white marks on its back, similar to the markings on marble, hence the name. This is the most visible characteristic you can use to distinguish the brown marmorated bug from the common green shield bug with the approach of the winter months. That’s because it is during this period that the green shield bug actually shifts its colour to brown. It does that to better camouflage itself in its changing surroundings.

Both species are close relatives of the family Pentatomidae. You can also spot the predatory shield bug (Picromerus bidens) which looks a lot like a brown marmorated stink bug. Its most keen difference is its sharp shoulders. This species can often be found in gardens, and can actually be quite beneficial.

How to tell adults and nymphs apart

Adults shield bugs will have a pair of fully developed wings that they fold on top of their body. This is how you can easily identify a nymph from an adult, as nymphs have no wings.

The nymphs of the brown marmorated stink bugs are yellow and red. They have bright red eyes during all nymph stages. The nymphs of the green shield bugs are different shades of green throughout their stages and carry red stripes on their antennae.

The transition between nymph stages happens through moulting. Each time a nymph moults, it sheds its skin and gets a bit bigger.

Are shield bugs dangerous?

These insects don’t pose a threat to human health. There are no known diseases spread by them and they don’t cause structural damage to properties. Although, they could be a nuisance when buzzing around your home at night, looking for a warm surface to land on or hovering around a light source.

As the shield bug has a decent size of roughly two centimetres long and wide, the buzzing from its wings can be quite loud. Not only that but when disturbed or crushed, green shield bugs let out a pheromone from glands around their back that has a particular musty odour. This usually protects them from predators and disgusts humans as well.

All of the species tend to stick together in large groups, so if you find one or two inside your property, you best believe there are more. Shield bugs often group together in clumps to survive colder temperatures. You can find them in cracks and crevices somewhere warm and dry. Especially if you have a lot of indoor plants, they will be happy to take the offer.

Spotted too many shield bugs in your house?

Call in a professional to inspect and treat your property.

Add a valid postcode e.g. SE1 2TH

How to prevent shield bug infestations inside

Shield bugs are drawn towards our homes with the approach of colder weather. They gather around light sources and love getting sunbaths. You can often see larger groups of shield bugs resting on a wall that is hit by the sun. As the evening hours approach and the sun starts to set, they tend to search for entry points, towards the warmth and light they sense from the inside. Thanks to their flat bodies, they can easily slip through small gaps and cracks.

So, here are some steps you can take to keep bugs out in general:

  • Seal off any entry points.
  • Don’t leave outdoor lights on if not necessary.
  • Install door sweeps.
  • Install window and vent screens.
  • Add a barrier of mulch half a meter wide around the house.

These steps will prevent a large array of pests from entering your property, so if you notice any intruders, those should be on your to-do list.

Specifically for shield bugs, you should:

  • Inspect your shopping bags before bringing them inside.
  • Pay close attention to any produce from your garden that you bring inside, especially salads.
  • Carefully check your laundry if you hang your clothes to dry outside.

Shield bugs love to take hitchhikes inside your property, so keep an eye out for them. Additionally, you can regularly treat the perimeter of your house with pesticides to limit any insects crawling inside. Or you can rely on the services of professionals, as they are well familiar with the different pesticides and how to apply them. If you are dealing with an in-house infestation, a general fogging service will help eliminate unwanted guests.


  • Shield bugs and stink bugs are actually the same;
  • We usually carry shield bugs inside our homes accidentally;
  • Although they can be a major nuisance, shield bugs are not dangerous to humans;
  • They tend to stick in large groups, especially throughout the winter months.


Do you have any personal experience with shieldbugs? We will be glad to read all about them in the comments section! Please, share!

Image source: Shutterstock / Cherries

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