What Every Gardener Should Know About Stink Bugs

28/July/2023 by Sophie

Most stink bugs don’t exactly make us jump for joy when we spot them in the garden. If you’ve ever encountered these little guys, you know they can be pretty repulsive. Nowadays, stink bugs are pretty common in Montreal, and they have a tendency to munch on various vegetables and other plants. But don’t worry – we’re all about finding eco-friendly ways to manage your pests around here.

Why are they called stink bugs?

Stink bugs have a unique defence mechanism. They have scent glands hidden on the back of their abdomen and under their thorax. When they feel threatened or get harmed, they release a stinky liquid from these glands. This smelly liquid contains compounds called aldehydes, which can be found in places like your old biology classroom as formaldehyde, or even wafting off the cilantro leaves on your kitchen counter.  The brown marmorated stink bug (BMSB), in particular, emits a skunk-y, cilantro-y aroma when it’s disturbed or killed.

When and where to find them

Understanding their seasonal patterns empowers us to be proactive in our garden defence. Stink bugs have three main life stages: egg, nymph, and adult. As temperatures rise in spring, they will start coming out of their winter hiding spots. You’ll find them busily laying their eggs on the underside of leaves in your garden, setting the stage for the next generation of stink bugs.

Stink bug populations reach their peak activity in the heat of the summer, between June and August, when they can become quite the garden party crashers. This is when we must be extra vigilant in monitoring their presence, as they can quickly multiply and become a nuisance for our plants. Stink bugs eat the sap they find in plants – they have a proboscis (I prefer the term mouth-straw) which they use to pierce the fruits, buds, leaves and stems of plants (and sometimes er- other insects) so they can suck up the liquid.

As the autumn breeze starts to roll in around September and October, stink bugs will start seeking warm and cosy spots to spend the winter. They’ll crawl into leaf litter or head indoors, attempting to hibernate inside the house. But don’t worry – they won’t reproduce in your home and will want to leave once spring comes back around.

To find stink bugs in your garden, try taking a look on the underside of leaves for their eggs. Adults can get to be quite large, about the size of a fingernail. You can find traces of their presence on the leaves and stems of plants, but the most obvious place you can find their mark is right on your vegetables. Their damage looks like cloudy, white, superficial spots that are easy to notice once you know what you’re looking for.

Source: Grainger County

3 Common Stink Bugs in Montreal

So here lies a challenge – distinguishing between beneficial and harmful stink bugs can sometimes be tricky. The last thing we want to do is inadvertently harm our garden defenders while trying to address pest issues! When it comes to stink bugs in Quebec, we’ve got quite a few species making their presence known in our gardens, and there are three brown stink bugs that look incredibly similar. It’s worth knowing the difference between these ones because while two are our friends, there is one that is a garden foe.

Brown Marmorated Stink Bug

First up, we have the Brown Marmorated Stink Bug (Halyomorpha Halys), or BMSB for short. Hailing originally from Asia, this invasive species has made its mark in North America as a big nuisance in gardens, crop fields, and parks alike. Their sap sucking causes scarring and pitting to fruits and vegetables, as well as introduces fungi and bacteria as they pierce into fruits and vegetables. They are also one of the largest of the stink bugs, and their proboscis is long and slender. What differentiates BMSB from the other two stink bugs is their thin proboscis, the white bands on their legs and antennae, as well as their smooth, rounded shoulders.

Source: Steve Schoof via StopBMSB.org

Rough Stink Bug

Another similar looking stink bug is the beneficial Rough Stink Bug (Brochymena spp.), a native North American genus sporting a textured, roughened appearance on its shield-shaped body. And while they do eat plants like corn, soybean, and apples, these little warriors contribute to a healthy garden ecosystem by being omnivores – they also keep other insect pest populations in check. You can tell them apart from BMSBs from their two “teeth” at the front of their faces, and the edges of their shoulders are serrated.

Source: Eric R. Eaton via Bug Eric

Spined Soldier Stink Bug

The third look-alike I’d like to introduce to you is my personal favourite, the Spined Soldier Stink bug (Podisus spp.). These are the true superheroes of our gardens – they are all about eating other bugs. As they play a vital role in controlling pest populations naturally, Their importance in maintaining a balanced ecosystem cannot be overstated.

You can notice these guys by the spiky projections on their shoulders, as well as their thick proboscis. 

Source: P.M. Shrewsbury via Bug of the Week

Natural Pest Management 

In your ecological gardening practices, promoting biodiversity and natural ecosystems is key! Beneficial insects, birds, and predators can lend us a helping hand in controlling pests we find in our gardens.  Ladybugs, praying mantises, swallows and sparrows will all happily feast on the stink bugs in your yard.  By encouraging their presence in your yard, you’ll notice a natural regulation of these pest populations.

Fostering biodiversity and nurturing a healthy ecosystem means you can keep stink bug numbers in check without using any synthetic chemicals. Planting a diverse range of flowers and herbs, for example, would attract beneficial insects like hoverflies, which feast on stink bugs and other garden pests. Even birds like cardinals, for example, enjoy snacking on stink bugs. By creating a welcoming environment for these helpers, you’re fostering a sustainable and balanced ecosystem that’ll naturally keep stink bugs in check.

Source: Claude Laprise via Unsplash

When using integrated pest management in your garden, regular garden monitoring is crucial! Early detection is your secret weapon to prevent those infestations from spiralling out of control. Keep an eye out for stink bug presence, especially during their peak activity times in the season. By catching them early, you can nip potential problems in the bud, and avoid any major headaches down the line.

Oftentimes, the idea of completely wiping out a pest population is impossible, and trying to completely remove them from your garden can be expensive and unsafe. If you do notice that your stink bug populations are reaching a tipping point, consider homemade remedies and organic sprays instead of reaching for the harsh chemicals. Try removing them by hand when you spot them. Or spraying leaves with soapy water, neem oil, or garlic spray can work wonders. Plus, you won’t harm beneficial insects or upset your garden’s harmony as much.

Have you run into any stink bugs in your gardens this summer? Let me know in the comments! And as always, happy gardening!

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