Life Cycle Of Western Conifer Seed Bug: How Long Does This Pest Live?

The western conifer seed bug is a very common pest in North America. In this article, we talk about the life cycle of western conifer seed bug, so that you know how long you will have to face this menace.

The Western Conifer Seed Bug (WCSB), is one of the main bugs of the Coreidae family. 

Found all around the US, these bugs were first found in Pennsylvania in July 1992 and are known for their habit of feeding on conifer seeds. 

But how do they grow up and live out their lives around conifer trees? In this article, let us tell you a bit about conifer seed bugs and their life cycle.

Life Cycle Of Western Conifer Bug
Western Conifer Seed Bug


The Western Conifer Seed Bugs reproduce as one generation every season. They lay eggs that hatch within ten days and feed on conifers. 

Despite the name, they are not seed bugs; they are from a family of leaf-footed bugs.

Their reproduction season lasts through August, and then they overwinter. 

The nymphs develop mouth-parts that let them feed on seeds and go through five stages before developing into adult bugs. 

Laying Eggs

The name of the bugs comes from their relation to their host conifers. 

Adult seed bugs overwinter in cold weather and emerge in the early summer months when they start feeding on pinecones and cone seeds. 

Females lay eggs in rows on the needles of coniferous trees, which include pine, red pine, spruce, and hemlock. 

The egg-laying season lasts from mid-June to early August, and these eggs take ten days to hatch. 


After hatching, the nymphs take around five weeks to mature as adults. The small ones feed on the soft tissue and needles of the cones. 

Over the next few weeks, the lives of these nymphs grow up and start feeding on ripe conifer seeds by early fall. 

For certain species, the reproduction process may differ. The species found in the US is known as Univoltine since they grow as a single generation every year. 

The Conifer seed bug species in Europe complete two generations every season, and some in tropical Mexico reproduce three generations every year. 

Life Cycle Of Western Conifer Bug
Western Conifer Seed Bug


At the end of every summer, one generation of Western conifer seed bugs dies out. The new generation of adults starts to overwinter and prepare for the next cycle. 

Most of the adults overwinter under the bark of pine trees and inside Douglas fir. 

These bugs also overwinter inside the nests of rodents and birds. In certain cases, for the lack of space, these bugs overwinter inside buildings. 


There are more than 30 species of trees that can become a Western Conifer bugs’ home. The common host conifers can be fir, spruce, pine, holly, cedar, and pistachio. 

These bugs are native to North America and are known to expand eastward, found as far as southern New Brunswick. 

These bugs were first found in Pennsylvania in the ‘90s and spotted moving North and Eastward. 

Their habitats were focused around the Pacific Northwest in the states of Washington, Oregon, and Idaho.

What Damage Do They Cause?

Western Conifer Seed Bugs are fairly harmless creatures that live off conifer trees in the wild. 

But if they are infesting conifer trees, there is a chance that the trees are in danger. And if you are living around a population of fir trees, your home could also be in trouble. 

Here are a few things you should know about conifer bugs being around you and your home. 

Damage To Douglas Fir Cones

One of the favorite trees for Western Conifer Seed Bugs to feast on is the Douglas fir. The nymphs and adults both feed off the needles, seeds, and cones of the Douglas fir, often resulting in the loss of the crop. 

The nymphs use their small mouthparts to feed on the sap and soft tissues of green cones and twigs. 

Life Cycle Of Western Conifer Bug
Western Conifer Seed Bug

While this may be harmless for the tree itself, the cones of fir trees can be damaged by extensive feeding of the bugs, resulting in the failure of the seeds to develop. 

In most cases, the bugs can have a direct impact on the growth and viability of conifer seed crops. 

Nuisance Pests During Winter

Western Conifer seed bugs are harmless in the sense that they do not bite or sting humans. But when they are making their way into homes and buildings, they can become a real nuisance. 

With areas that have a high population of conifer trees, the bugs can enter homes to overwinter. 

Sometimes with the high temperatures, the insects can become active indoors. In summer, they also move around from one tree to another, often entering homes. 

In a number of areas in the Northeastern US, these insects multiply at alarming rates in the overwintering months, finding a safe place from the cold temperatures. 

They are usually looking for warmth and shelter but cause an extremely disturbing odor when they attempt to be removed. 

Stink Bugs

WCSBs is a type of stink bug, ie, they give out a foul odor if they feel threatened, as a way to deter predators.

Many people who face these bugs often complain of the horrible stink they keep getting from their kitchens, bathrooms, attics, and other such places where these bugs hide.

Frequently Asked Questions

How do western conifer seed bugs get in your house?

Western conifer seed bugs enter homes through cracks in a building, wall voids, and, most commonly, through open windows. 
They usually try to find their way into homes in winter, looking for shelter and warm temperatures.

How do I get rid of western conifer seed bugs?

Eliminating gaps on window frames and tightening window screens can be the most effective way of keeping out conifer bugs. 
There is no insecticide that can be used on these leaf-footed bugs. Some of the small ones can be removed by hand.

Is the western conifer seed bug harmful?

The Western Conifer Seed Bugs are not harmful to humans directly since they do not bite or sting. They can become a nuisance in homes if they enter in large numbers and might require pest control to avoid an infestation.

Can western conifer seed bugs survive winter?

Wester Confider Seed bugs avoid winters because they cannot survive extremely cold temperatures. They try to find their way into buildings to overwinter, but they die out if they do not get enough moisture and the cover of conifer bark.

Wrap Up

So, unless there are seed bugs swarming your house all at once, you don’t have much to worry about the WCSB. They are wild creatures that stick to their habitat of coniferous trees, wandering into homes only when they are trying to be safe. 

Occasional pest control in extreme situations can help you live comfortably around them. Thank you for reading, and keep away from the pinecones in summer!

Reader Emails

Over the years, our website, has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Long Necked Seed Bug


Subject: Webspinner? Location: Austin May 20, 2015 12:05 pm They’re everywhere Signature: Danyel
Long Necked Seed Bug
Long Necked Seed Bug
Dear Danyel, This is a Long Necked Seed Bug, Myodocha serripes, and according to BugGuide, they feed on:  “Seeds of strawberry and St. John’s wort. Sometimes a pest of strawberries.”  There is contradictory information in the El Dorado Springs Sun Online in an article LONG-NECK SEED BUGS BENEFICIAL IN STRAWBERRIES where it states:  “Jill Scheidt, agronomy specialist with University of Missouri Extension, has seen several long-neck seed bugs in many strawberry patches during the late spring.  ‘Long-necked seed bugs are a beneficial insect in strawberries,’ said Scheidt.”  The article contains information from another expert:  “They can be found under leaf litter in early spring and in fields and under artificial lights in the summer. Long-necked seed bugs overwinter in woodland and migrate to fields in the spring and summer; they are attracted to lights.  According to Richard Houseman, University of Missouri plant sciences professor, long-neck seed bugs will sometimes feed on strawberry seeds but are rarely a threat needing treatment. They do feed on pests like St. John’s wort and other small insects.”  Do you live near where strawberries are cultivated?

Letter 2 – Burning Man Bugs: Reported by What’s That Bug? in 2010!!!


Seed Bugs attracted to lights at night.
Seed Bugs attracted to lights at night.
August 24, 2015 Populous aggregations of Seed Bugs at Burning Man (See Gizmodo) are attracting quite the internet buzz, and they are being likened to Biblical plagues, but What’s That Bug? covered similar aggregations of Melacoryphus lateralis in the Organ Pipe Cactus National Monument, Arizona in 2010.
Aggregation of Seed Bugs from the desert.
Aggregation of Seed Bugs from the desert.

Letter 3 – Long-Necked Seed Bugs


Subject: holy cow, there’s a lot of ’em Location: Chicago, IL September 27, 2015 2:15 pm I was weeding this afternoon, in a spot that I should have weeded months ago. The weeds were a low ground-cover, pervasive. As I moved along, each time I cleared an area, there’d be a bunch of these guys under the weeds, anywhere from as small as 1/8 inch up to about 1/2 inch. This was along the south wall of the house along the field-stone-and-mortar foundation that rises about 4 feet above the soil bed (we’re told the house was built around 1900 in the city of Chicago). You were kind enough to post my last submission: 2006/03/03/newly-emerged-polyphemus-moth/ I waited 9.5 years to ask again, I didn’t want to seem greedy 😉 Signature: Todd
Long-Necked Seed Bugs
Long-Necked Seed Bugs
Dear Todd, We hope you don’t wait another 9.5 years to write back to us.  Your image clearly depicts both winged adult and immature Long-Necked Seed Bugs, Myodocha serripes, a species that according to BugGuide:  “Two generations per year; overwinters as adult in leaf litter or under bark of trees in woodlands.”  BugGuide also indicates it feeds on “Seeds of strawberry and St. John’s wort. Sometimes a pest of strawberries.” 

Letter 4 – Whitecrossed Seed Bug


Subject: What is it? Location: Brookings OR January 3, 2016 3:16 pm Haven’t seen this bug before. Signature: John Boye
Whitecrossed Seed Bug
Whitecrossed Seed Bug
Dear John, The color and markings on this Whitecrossed Seed Bug, Neacoryphus bicrucis, are quite distinctive.  According to BugGuide, they are found in “Fields, meadows; adults come to light.” Dan, Many thanks for taking the time to reply! I’ll look for more info on him via the web. Best Regards, John Boye

Letter 5 – Whitecrossed Seed Bug


Subject: What’s this bug? Location: New York, NY December 28, 2015 6:44 am I live in Jamaic Queens, NY and found this on the inside of my screen. Signature: Not necessary
Whitecrossed Seed Bug
Whitecrossed Seed Bug
This is a harmless Whitecrossed Seed Bug.

Letter 6 – Whitecrossed Seed Bug


Subject: Bug identification Location: Raleigh, NC January 9, 2016 2:36 pm Do you know what this is? Crawled out of my bicycle handle bars in NC, Jan 2016 Signature: Snt
Whitecrossed Seed Bug
Whitecrossed Seed Bug
Dear Snt, This is the third image of a Whitecrossed Seed Bug, Neacoryphus bicrucis, we have posted since the New Year, and it is quite interesting that they are not at all localized, with the previous two postings originating in Oregon and New York.

Letter 7 – Mediterranean Seed Bug in Washington


Subject: Boxelder Relative? Location: Snohomish, WA March 30, 2016 4:18 pm We have numerous of these on our south facing exterior walls. The closest images I have found that look like these are the Boxelder, although ours do not have the reddish-orange coloring. I always attempt to let nature police itself the best I can. (Paper wasps in outdoor light fixture annually, which my wife hates.) We have many jumping spiders that patrol the same south facing walls, but I haven’t seen any of these little beetles fall prey to them yet. Hopefully, these are not an infestation that needs to be addressed. Thank you for your time! Signature: CEROE
Mediterranean Seed Bug
Mediterranean Seed Bug
Dear CEROE, We believe this is a Mediterranean Seed Bug, Xanthochilus saturnius, a species that according to BugGuide is:  “native to Europe and the Mediterranean, adventive in NA (WA-CA) and now locally abundant.”  According to the Pacific Northwest Insect Management Handbook:  ” There is very little known about these bugs, possibly because they are not major economic pests. They do cause anxiety among homeowners, and costly eradication expenses.”  The PNIM Handbook also states:  “Even though they do no damage to house, humans, or pets, these seed bugs become a huge annoyance and costly to exterminate when they migrate into households.”

Letter 8 – Dirt Colored Seed Bug Nymph may be California False Chinch Bug


Subject: Help! tons of these things appeared 2 days ago Location: Phoenix, Az April 12, 2016 8:30 pm I live in Phoenix Az. I do have a front yard garden of some herbs, tomatoes, and artichokes. I don’t think the bugs are there for the garden. They spread out through the dirt portion of the yard and have trails (4-5 trails that they’re following) all the way past the garden and into the backyard. I found false cinch bugs have similar body shape, but not the markings. Our neighbor is redoing his entire house, so I’m wondering if that’s where they came from? Signature: Morgan
Possibly California False Chinch Bug Nymph
Possibly California False Chinch Bug Nymph
Dear Morgan, Last spring we posted an image of similar looking nymphs, and at that time we wrote:  “These are immature True Bugs, and nymphs can be very difficult to identify.  …  we suspect you may also have Dirt Colored Seed Bugs in the family Rhyparochromidae.”  When we received images of the adults, we tentatively identified them as California False Chinch Bugs, Xyonysius californicus, but alas BugGuide does not have any young nymph images. Thank you! That gives me enough info so I don’t have to worry about them. I really appreciate he quick reply.

Letter 9 – Whitecrossed Seed Bug


Subject: red & black bug Location: Western Washington State April 18, 2016 12:25 pm Hi Mr. Bugman, I took this photo on my deck last night. There were 20-30 of these red and black bugs all over my Lamb’s ear plant. I live in the Western slopes of the Cascade Mountains in Washington state and have never seen this particuler bug before. Can you ID it? Signature: Machele Brodie
Whitecrossed Seed Bug
Whitecrossed Seed Bug
Dear Machele, This Whitecrossed Seed Bug, Neacoryphus bicrucis, according to BugGuide, is found in “Fields, meadows; adults come to light.”

Letter 10 – White-Crossed Seed Bug


Subject: What’s this bug? Location: Edmonds, WA May 18, 2016 10:33 pm Hello! This bug was on my exterior kitchen door today (May 18th) in Edmonds, Washington. It was maybe 1/4″ long, if I remember correctly. I tried googling, reverse image searching, asking friends, and using your website, but to no avail. I’d love to know more about it. Thanks for your time! 🙂 Signature: Cat Jackson
Whitecrossed Seed Bug
Whitecrossed Seed Bug
Dear Cat, With the strong white background and the graphic, saturated coloration on this Whitecrossed Seed Bug, Neacoryphus bicrucis, your image looks like a professional studio portrait. That’s it!!! And that was so fast, thank you!!! FYI I took that photo with my iPhone and a clip-on macro lens that I got in a kit for ~$7. Whitened the background with Facetune. Modern technology is pretty cool. 🙂

Letter 11 – Whitecrossed Seed Bug


Subject: Insect on Butterweed Flower Location: SW Ohio May 24, 2016 2:44 pm I took this picture yesterday May 23, 2016. The insect was on a butterweed flower. I am located in S.W. Ohio between Cincinnati & Dayton. I’ve checked a lot of insect pictures but could not find this one. The closest thing that I could find was a red bug. I am an Ohio Certified Volunteer Naturalist. Signature: Wade Hall
Whitecrossed Seed Bug
Whitecrossed Seed Bug
Dear Wade, This is a Whitecrossed Seed Bug, Neacoryphus bicrucis, and though it is a relatively wide ranging species, we have very few submissions until recently.  We don’t know why, but for some reason sightings of Whitecrossed Seed Bugs to our site have increased significantly recently. Thanks for your quick reply.  I didn’t think I’d ever hear back from anybody. Wade Hall – OCVN

Letter 12 – Probably Dirt Colored Seed Bug Infestation


Subject: Bug invasion! Location: Los Altos CA June 27, 2016 5:42 pm Hi bugman! I’m having a bit of a freak out here in Northern California (Los Altos), and hope you can help. There has been a sudden appearance of a large number of tiny black and tan bugs at my house. They seem to come from the foundation of the stucco house and swarm the walls and windows, and stream in through cracks in doors and windows! They show up in the late afternoon when it gets warm, and there are thousands and thousands of them, and then they disappear as it cools down in the evening. They don’t seem to fly, rather scurry along very quickly and seem to fall down from the wall if scared. They appear en masse on one wall one day and then will be greatly diminished in a day, but then appear along another wall a day or two later. We have had a drought here, so the ground is not damp, and they don’t look like the pictures of fungus-eating springtails I saw online. What could they be and what should I do to stop the invasion? Thank you so much for any guidance! Signature: Disturbed by the force Oh, I forgot to tell you about the size…they are tiny! Some are small like the size of a flea, and some are barely visible like the size of pepper. They also don’t fly, and don’t seem to bite, although I haven’t really given them a chance to try. Thank you again!
Probably Dirt Colored Seed Bugs
Probably Dirt Colored Seed Bugs
Dear Disturbed by the force, Your insects look identical to the ones in this two year old posting from Northern California that we identified as potentially Dirt Colored Seed Bugs in the family Rhyparochromidae. 
Probably Dirt Colored Seed Bugs
Probably Dirt Colored Seed Bugs
Hi Daniel, Thank you very much for your help! Still quite disturbing to see those tiny dirt-colored seed bugs everywhere, but I am so glad to know what they are. I can now research them by name and see the best way to get rid of them. Thank you again, Elise

Letter 13 – Long Necked Seed Bug


Subject: Household insect with strange thick parts of legs Location: New Jersey July 22, 2016 11:21 pm Hello, I have seen these insects twice in my apartment in suburbia lately. One much smaller than this, about a centimeter long, and then this one, which was about 3 centimeters in length. Sorry the photo is slightly blurry, but I hope you can see the shape. I know it’s not a roach, the back isn’t the right shape. I don’t think it’s a beetle. I am perplexed outside of that though: it has these thickenings near its joints in its legs that remind me of bees, and a head that reminds me of that, too, but it doesn’t have the hemiptera waist. My best guess is a true bug, but that’s pretty vague! I tried to grab it so I could look at its mouth parts, but it intelligently moved away. Signature: Sylvia
Long Necked Seed Bug
Long Necked Seed Bug
Dear Sylvia, This is a Long Necked Seed Bug, Myodocha serripes, a species that according to BugGuide:  “overwinters in woodlands, migrating to fields in spring/summer; adults attracted to lights” and “Sometimes a pest of strawberries.”  We love your dedication to learning its identity, including trying to see its mouth parts. 

Letter 14 – Western Conifer Seed Bugs in England


Subject: Re: Leaf Footed Bug / Unknown?? Location: South East of England, Harwich, Essex September 15, 2016 4:09 pm Dear Daniel (The Bugman), Please would you kindly consider helping me identify the bug in the photos? We have come across 4 of these bugs in less than 72 hours. The first one found on my wardrobe door – the next appeared on the bathroom net curtain. Just tonight, we found another walking across a bed and to our horror another in that same bed less than 20 minutes later. As you can imagine it’s proven to be quite alarmingly as we have never seen one or these before in our life – let alone four of these in quick succession. It’s a worry in case they are dangerous insect. I don’t know if it’s a coincidence or not, but a person in my household got bitten twice on the arm in the night a week ago and whatever it were pierced the skin to draw blood. She often gets beaten by gnats due to having a rare blood group though it never pierces the skin like it did on this occasion. I could be over-worrying here for nothing although the insect had similar resemblances to “Leaf Footed Bug” except I don’t think we get those in the UK. We also found a Black Widow Spider in our shed in recent weeks meaning anything is surely possible given this heatwave and hotter weather. I would appreciate your assistance if your team has time. 🙂 Thank you so much, Signature: Chris Hi Daniel, Here is an update. We just found another one since my email. This is a crystal clear photo Any ideas please? :/ Cheers, Chris
Western Conifer Seed Bug
Western Conifer Seed Bug
Dear Chris, Thanks for sending a sharper image.  This is indeed a Leaf Footed Bug, more specifically a Western Conifer Seed Bug, Leptoglossus occidentalis, a species native to the Pacific Northwest.  Its range began expanding in the in the mid 20th Century, and now it is found across North America as evidenced by this BugGuide map.  We suspect the range expansion is related to human travel and to the fact that this species often enters homes to hibernate as the weather begins to cool.  Early in the 21st Century, Western Conifer Seed Bugs were reported in Europe and now sightings in the UK and other parts of Europe are relatively frequent.  According to BugGuide:  “recently introduced to Europe (first record: Italy 1999) and now widespread there.”  According to British Bugs:  “A very large and spectacular squashbug which has characteristic expansions on the hind tibiae and a white zigzag mark across the centre of the forewings.   Native to the USA and introduced into Europe in 1999, it has since spread rapidly and during 2008-2011 influxes of immigrants were reported from the coast of southern England, with a wide scatter of records inland.  The bug feeds on pines and is probably well-established here; nymphs have been found at several locations. It is attracted to light and may enter buildings in search of hibernation sites in the autumn.” Hi Daniel, Thank you so much for the quick response! 🙂 I must apologise for my delayed response thought had already replied. Your response was very reassuring and a huge relieve! Keep up the great work! 🙂 Cheers, Chris

Letter 15 – Invasive Mediterranean Seed Bug


Subject: Can’t identify this bug Location: Eastern San Francisco bay area California September 30, 2016 8:17 pm Good day, Found this big swimming in a child’s pool I use for my siberian husky. The husky had a severe allergic reaction to an insect bite, and I found this critter while trying to find what could have bite the husky. Thing it is of the leaf foot verity but not sure. Any thoughts? Signature: Shawn
Mediterranean Seed Bug
Mediterranean Seed Bug
Dear Shawn, This is an invasive Mediterranean Seed Bug, Xanthochilus saturnius, a species that according to BugGuide is:  “native to Europe and the Mediterranean, adventive in NA (WA-CA) and now locally abundant.”

Letter 16 – Whitecrossed Seed Bug


Subject: What’s this interesting looking bug? Location: Alpharetta, GA April 2, 2017 6:11 am I have never seen one of these and I cannot find a picture of one. This one was sunning on my garage pillar in early spring north of Atlanta. My backyard has a 20 foot wooded buffer around a small stream. This bug was in my front yard -a typical suburban landscaped area. Signature: Lynn
Whitecrossed Seed Bug
Dear Lynn, The aptly named Whitecrossed Seed Bug, Neacoryphus bicrucis, is also called the Ragwort Seed Bug, according to BugGuide, where the habitat is listed as “Fields, meadows; adults come to light.”

Letter 17 – Dirt Colored Seed Bug in Germany


Subject: Please not a cockroach…. Location: Berlin, Germany April 4, 2017 11:10 pm Dear Bugman, I keep finding these little guys in our entry way and adjacent kitchen (mostly in the kitchen). Occasionally, I will find them in other areas – dining room, bathroom, living room. I have seen an average of one a day since we moved in last summer, except during the winter, when I saw about one every few weeks. I can’t figure out where they are coming from or going to. They don’t seem to be into food or water. We have bananas and butter out 24/7, and I’ve only found one on the bananas and never in the butter. They aren’t under the sink, that I have seen. They are often just on the floor or the wall or the counter. I’ve tried to sneak in and pop on the light in the morning to find more skittering away, but I never find more. They don’t try to run away unless they are bothered (like me trying to scoop them into a ziplock). We have sprayed the entry way a couple of times for ants, which kills other beetles and spiders as well, but these guys seem to be somewhat immune to that. We are in Berlin, Germany. The photo has been lightened a little to make the markings easier to see – it is usually darker and hard to make out the markings on the upper back, and it includes a quarter for size reference. I can’t sleep at night for fear of infestation, whatever it is. Can you please help??? Signature: Buggy in Berlin
Dirt Colored Seed Bug
Dear Buggy in Berlin, This is not a Cockroach.  We believe it is a Dirt Colored Seed Bug in the family Rhyparochromidae.  At first we thought it might be Rhyparochromus vulgaris, a European species that has been accidentally introduced to North America where it is causing residents distress as it reproduces in great numbers, but the markings are subtly different based on BugGuide images. Fantastic! This is great news. I can’t tell you the peace of mind that this gives me. Thank you so very much. I only wish I would have thought to ask you sooner. I can finally sleep at night!

Letter 18 – Possibly Dirt Colored Seed Bug


Subject: What type of insect is this? Location: Southern California July 3, 2017 10:53 am Dear Bugman, We are at the beginning of summer, and we’ve experienced strong heat in my region this past week. This comes after decent winter rainfall. I live in southern california near the San Bernardino mountains. These small insects have been staring my backyard in large numbers, I first thought they were mosquitoes, but after taking a few close up shots I’m having second thought. Can you help us identify this bug? Signature: Ricardo
Possibly Dirt Colored Seed Bug
Dear Ricardo, This might be a Dirt Colored Seed Bug in the family Rhyparochromidae which is pictured on BugGuide.  There are several invasive, exotic species currently causing problems in western North America, but we do not believe this is either the Mediterranean Seed Bug or the Elm Seed Bug

Letter 19 – Long-Necked Seed Bug


Subject: Baby flying bug Location: Clarksburg, WV July 19, 2017 1:20 am I found this bug flying up on my ceiling and would like to know what this is. Signature: Heather
Long-Necked Seed Bug
Dear Heather, Based on this BugGuide image, we are confident this is a Long-Necked Seed Bug, Myodocha serripes.  According to BugGuide, it feeds on:  “Seeds of strawberry and St. John’s wort. Sometimes a pest of strawberries.”

Letter 20 – Mediterranean Seed Bug


Subject: Bug ID Location: Southeast WA August 6, 2017 5:35 pm Having hundreds of these on my patio, walls, windows, etc. over the last couple weeks. Can you ID? I’m in eastern dry part of WA, temps have been near 100 during the last 2 weeks. Signature: Gerry
Mediterranean Seed Bug
Dear Gerry, This is a Mediterranean Seed Bug, Xanthochilus saturnius, an introduced species that has naturalized along the west coast states in North America.  According to the Pacific Northwest Insect Management Handbook:  ” There is very little known about these bugs, possibly because they are not major economic pests. They do cause anxiety among homeowners, and costly eradication expenses.”  The PNIM Handbook also states:  “Even though they do no damage to house, humans, or pets, these seed bugs become a huge annoyance and costly to exterminate when they migrate into households.”

Letter 21 – Mediterranean Seed Bug


Subject:  They are everywhere! Geographic location of the bug:  My Basement, northeast Washington state Date: 09/28/2017 Time: 12:48 AM EDT What are these? Are they harmful? How you want your letter signed:  Creeped Out
Mediterranean Seed Bug
Dear Creeped Out, This is an invasive Mediterranean Seed Bug, and according to BugGuide:  “native to Europe and the Mediterranean, adventive in NA (WA-CA) and now locally abundant.”  Without natural predators on the west coast of North America, they are proliferating.  Though they are not specifically harmful, they are an annoyance when they are abundant, and we don’t believe there is any current information on the negative impact they might have on native species.

Letter 22 – Mediterranean Seed Bug


Subject:  Haven’t seen this before Geographic location of the bug:  Seattle Date: 11/24/2017 Time: 04:40 PM EDT Found a bunch mostly dead outside in a plastic bin that had contained firewood a week ago (early in November) and just now spotted this one in the basement.  They’re about a cm long including legs and antennae. How you want your letter signed:  Liz
Mediterranean Seed Bug
Dear Liz, Despite the lack of clarity in your image, the Mediterranean Seed Bug, an Invasive Exotic species, it still recognizable. 

Letter 23 – Immature Western Conifer Seed Bug, we believe


Subject:  please identify Geographic location of the bug:  ny Date: 02/14/2018 Time: 08:09 AM EDT Your letter to the bugman:  hello sir, I found this in my attic…I dont ln kn ow what it is.. How you want your letter signed:  thank you?
Possibly Immature Western Conifer Seed Bug
This is an immature True Bug in the family Coreidae, the Leaf Footed Bugs, and we believe it is the nymph of a Western Conifer Seed Bug (see BugGuide) a species that enters homes as the weather cools so it can hibernate over the winter.

Letter 24 – Mating Whitecrossed Seed Bugs


Subject:  Red and black bugs with triangle pattern on the back Geographic location of the bug:  Seattle, WA Date: 07/17/2018 Time: 01:26 PM EDT Your letter to the bugman:  What is this bug?  Is it bad for my house and my garden?  If it is, what is the best way to kill/remove them? Thank you. How you want your letter signed:  Tony Chan
Mating Whitecrossed Seed Bugs
Dear Tony, These are mating Whitecrossed Seed Bugs and according to BugGuide an alternate name is  “Ragwort Seed Bug” which we interpret to mean that it will feed on seeds of ragwort, reducing the subsequent generations of what is widely considered a weed, though according to Wikipedia:  “Although the plant is often unwanted by landowners because it is considered a weed by many, it provides a great deal of nectar for pollinators. It was rated in the top 10 for most nectar production (nectar per unit cover per year) in a UK plants survey conducted by the AgriLand project which is supported by the UK Insect Pollinators Initiative. It also was the top producer of nectar sugar in another study in Britain, with a production per floral unit of (2921 ± 448μg)”.  Since Seed Bugs feed on seeds, they are not normally considered injurious to plants.  We do not provide extermination advice.

Letter 25 – Elm Seed Bug


Subject:  Is this a kissing bug? Geographic location of the bug:  Missoula, MT Date: 08/04/2018 Time: 04:15 AM EDT Your letter to the bugman:  Found this indoors today,  it landed on my face and it smelled. Thought it could be a stink bug, but the red marking on its body remind me of a kissing bug.  Do kissing bugs smell? I don’t think it’s a west conifer seed bug since the head looks round, and I don’t think the legs were barbed but i’m not sure. I crushed it before getting a good luck at it. How you want your letter signed:  Jen
Elm Seed Bug
Dear Jen, This is not a Kissing Bug, but it is a problem nonetheless.  It is an invasive Elm Seed Bug, Arocatus melanocephalus, and according to BugGuide:  “Native to, and widespread in S. & C. Europe, established and spreading in w. NA” and “Can emit unpleasant odor, especially when crushed.”  BugGuide also notes:  “Doesn’t pose a threat to trees, but may show up indoors in huge numbers” and “Invades homes during summer, may stay through the winter.” 
Elm Seed Bug

Letter 26 – Mediterranean Seed Bug


Subject:  Different bug Geographic location of the bug:  Visalia ca Date: 07/27/2019 Time: 02:23 AM EDT Your letter to the bugman:  Found a little critter on my bed, thought it was a cockroach but the back looks different almost like a mask when u zoom it   what is this ? How you want your letter signed:  Lizzy
Mediterranean Seed Bug
Dear Lizzy, This is not a Cockroach.  It is an invasive Mediterranean Seed Bug, Xanthochilus saturnius, and it is pictured on pBase.  According to BugGuide:  “native to Europe and the Mediterranean, adventive in NA (WA-CA) and now locally abundant.”


  • 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.

  • 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.

5 thoughts on “Life Cycle Of Western Conifer Seed Bug: How Long Does This Pest Live?”

  1. I am having the exact same problem right now across the Bay in Newark. I used to live in Los Altos and have never seen anything like this. It feels like a biblical plague. I’m glad I can now put a name to the pest … and that I’m not alone in having this weird infestation.

  2. I discovered a big herd of them all around our home located eastern Saudi Arabia. They are harmless creatures however, annoying as they hard to be tracked….they are just what you’ve captured


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