How Long Do Western Conifer Seed Bugs Live? Their Life Cycle Explained

folder_openHemiptera, Insecta
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Seed bugs are becoming common across North America. If you see some at home, you might wonder, “how long do western conifer seed bugs live?” Let’s find out.

The western conifer seed bugs, scientifically known as Leptoglossus occidentalis, are fascinating little creatures famous for their appearance and feeding habits. 

These insects have a short life cycle, producing just one generation a year. It emerges from its overwintering sites in late May and lasts till the onset of winter. 

Interestingly, most people assume that they are seed bugs, but technically, they are not (despite the name). They are actually leaf-footed bugs.

Here are a few things you should know about these bugs and how they live their brief lives. 

How Long Do Western Conifer Seed Bugs Live
Western Conifer Seed Bug


How Long Do They Live?

Western conifer seed bugs (also known as pine seed bugs) belong to the Coreidae family and rear only one generation a year. 

The life cycle of these bugs begins around June and August when adult Seed Bugs lay their eggs. Nymphs start growing every week, going through five instar stages. 

The average western conifer seed bug matures for over five weeks, living till the end of the summer. 

As one generation of the bugs dies in the summer, the new adults look for a place to overwinter and survive for the next season. 

This is the time when they are most likely to invade homes, looking for warmth and shelter.

How Many of Them Are There in the World?

Western Conifer bugs have a very rapid life cycle ranging in the late summers, so it is difficult to track their numbers in the world. 

Since they multiply quickly and within weeks of each generation dying out, we can safely say that their numbers are growing.

Moreover, this bug has been spreading rapidly across the US. It was first observed here in Michigan in 1987 but has since gone to many other states.

Western Conifer Seed Bug


Where Are They Found?

The western conifer seed bugs are native to the land west of the Rockies from California to British Columbia.

Over time, these bugs found their way to New Brunswick, Ontario, and Nova Scotia, mainly in areas abundant with pine cones. 

In the US, the bugs have moved to many states, including Maine, New York, Pennsylvania, Massachusetts, Connecticut, and New Hampshire. 

Outside North America, the bugs are found in parts of Mexico and Europe, where they were accidentally introduced.

These bugs move around places with pine cones and find warm areas to lay eggs. 

What Do They Feed On?

The name of these bugs mainly comes from their diet. They feed on coniferous fruits like douglas-fir seeds and certain types of pine cones.

The nymphs start by feeding on seeds that they find inside pinecones. 

The way they eat these seeds is also interesting. These bugs inject a special enzyme into the hard-shelled pine cones, which turns their insides into liquid.

After that, they suck the contents of the pinecones easily. 

What is Their Life Cycle Like?

The western conifer seed bug has a lifecycle that consists of four stages over five weeks. The egg stage lasts about two weeks, during which the eggs hatch and the nymphs emerge. 

Nymphs go through five instar stages before becoming adults, which takes about two months. 

The overwintering stage begins in late autumn when the bugs seek places to shelter from the cold weather. 

They remain in this stage until spring when they become active again and begin feeding on coniferous trees.

Western Conifer Seed Bug


Frequently Asked Questions

How do you keep western conifer seed bugs away?

If you are looking for a way to get rid of conifer bugs at home, you should start by finding gaps in your walls. 

Fill up gaps in window frames, and tighten loose ends of window screens and doors. Try to find small crevices and holes in the walls and fill them up with caulking.

Since they are big enough to be picked out, you can try removing them by hand, though it might not prove effective. 

Can western conifer seed bugs survive winter?

These bugs overwinter during the cold season, usually in places like buildings or the bark of trees.

The bugs try to find their way into homes where they find warmth in this season. 

You can notice them coming in through window cracks and wall vents with a loud, buzzing sound. 

What kills seed bugs?

For seed insects like conifer bug seeds, neem oil can be an effective solution. Spray neem oil on them and around areas where you see them hiding. 

There are also a few insecticides that can prove effective, but it’s best to avoid using them inside your home. 

Vacuum your walls and close small cracks and vents in walls and doorways to prevent them from entering. 

Do western conifer seed bugs harm trees?

Western conifer bugs get their name from their food source, coniferous trees.

They are not dangerous to a whole tree if it’s just one or two of them.

However, these bugs can multiply quickly, and a large infestation can easily kill a large tree. 

Wrap Up

They may not be potentially harmful bugs, but you need to look out for the Western Confier Seed bugs becoming a problem in your home. 

These reddish-brown, almost innocent-looking bugs may not live very long, but they multiply fast and can be very difficult to control. 

Thank you for reading, and watch out for the bugs!


  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

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  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

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Tags: Seed Bugs

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8 Comments. Leave new

  • I live in Digby, Nova Scotia, Canada and we have them in our house every fall. Never in the house except for this year. Hate these things 🙁 I never saw these as a kid, what’s up with them?

  • Stink bug that is what we call them

  • My kids are petrified of them – because they are lousy “flyers” and will most likely land in your hair. LOL They STINK! – when harmed.
    I catch mine and throw them back outside – VERY harmless.

  • They love people and yes they do small bad but will not harm you

  • They look a lot like Bee Assassin bugs.

  • Kristina A. Larson
    October 27, 2015 6:35 pm

    Just this last Sunday I saw one of these critters on one of the windows after our potluck at church. I let it crawl around on my hand for a while and was going to let it fly to freedom, however it decided to hang out at one of the other windows near the doors. Not long after, some young (and probably naive) girl noticed it, grabbed a napkin, and uttering, “Eww, a bug,” snuffed out its life, in turn becoming revolted by the ensuing odor. I told her in a subtle tone it wouldn’t have hurt anyone (I didn’t want to sound like some PETA freak, lol) and that’s likely how they keep themselves from being eaten. But she said it was an ugly bug (???)

    Kristina A. Larson
    Ellsworth ME

  • Thanks for the photo! I found one of these in my bathroom sink today. Thought sure it was a kissing bug, but after looking at a few photos, it seems to just be a seed bug. (Southwestern Ohio)


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