The giant resin bee, scientifically known as Megachile sculpturalis, is an intriguing insect that has journeyed from its native home in eastern Asia to the United States. First introduced accidentally in the 1990s, this unique bee species has since established a presence in several states across the eastern US, adapting to its new environment while expanding its range source.
Solitary by nature, giant resin bees do not live in colonies as some other bee species do. Instead, they are categorized in the cavity-dwelling Megachilidae family and make their homes in abandoned wood cavities, like those found in trees or timber structures source. This bee species has managed to quickly adapt to its surroundings over the past few decades, raising curiosity and interest among nature enthusiasts and researchers alike
Giant Resin Bee Origin and Distribution
Giant resin bees (Megachile sculpturalis) are native to Eastern Asia, including countries like Japan and China. They were accidentally introduced to North America in the 1990s and are now present in most Eastern US states and Canada.
- Body: cylindrical with a black abdomen and yellow-brown thorax
- Size: females are larger than males, with the latter sporting a bright yellow “mustache” above their mandibles
- Wings: translucent with dark veins
Here’s a comparison table between giant resin bees and US native carpenter bees (Xylocopa spp):
|Feature||Giant Resin Bee||Carpenter Bee|
|Size||1.5-2.5 cm||2-2.5 cm|
|Color||Black and yellow-brown||Black with yellow hairs|
|Body Shape||Cylindrical||Robust and rounded|
|Nesting Location||Abandoned cavities||Bored tunnels in wood|
Behavior and Habitat
Giant resin bees are solitary, unlike social bees that live in colonies. They use abandoned cavities in trees or timbers for nesting, making them opportunistic dwellers. Resin bees commonly feed on nectar from flowers and also collect resin (as their name suggests) for building purposes.
In summary, the giant resin bee is an intriguing insect originally from Eastern Asia that has made its way to North America. Its distinctive physical traits and solitary habits distinguish it from native bees, offering a unique glimpse into the diverse world of bees.
Reproduction and Life Cycle
Mating and Nest Building
Giant resin bees (Megachile sculpturalis) follow a unique mating and nesting ritual. Males, being smaller (around 2/3 the size of females), are distinguished by a bright yellow “mustache” just above their mandibles1. After mating, the males die, leaving the females responsible for finding suitable nest sites1.
Giant resin bees are solitary cavity nesters2 that often use abandoned wood cavities for nesting, such as holes in trees or timbers3. They may also use crevices in structures1. Female giant resin bees collect sticky resin from trees and mix it with wood particles or mud to build their nests4.
Eggs and Larvae Development
Females lay eggs individually into brood cells which they construct using the sticky resin mixture4. Inside each cell, the female giant resin bee prepares a nutritious pollen and nectar mixture to nourish the developing larvae5. The larvae then consume this food, grow, and eventually pupate within their respective cells5.
Pros of giant resin bees’ reproduction:
Cons of giant resin bees’ reproduction:
|Giant Resin Bee||Native Cavity-Nesting Bees|
|Size||Large (females around 1 inch)||Smaller|
|Nesting||Abandoned wood cavities, holes, crevices||Various nesting habitat|
|Reproduction||Solitary; females build nests after mating||Varies (solitary or social)|
Ecological Impact and Concerns
Introduced and Invasive Status
Giant resin bees (Megachile sculpturalis) are native to eastern Asia, specifically Japan and China. They were introduced accidentally to the United States in the 1990s and are now found in most eastern US states. The bee is considered an adventive species, meaning it is non-native but usually not established.
Interaction with Native Species
Giant resin bees are opportunistic cavity dwellers, utilizing abandoned wood cavities for nesting. Some examples include holes in trees or timbers (source). They may compete with native species like Xylocopa spp. (carpenter bees) and other wood-nesting bees for these nesting sites.
- Male giant resin bees have a distinct yellow “mustache” above their mandibles
- Female giant resin bees are larger than males
- Both genders do not live in colonies and are solitary bees (source)
Pollination and Agricultural Impact
|Pollinator||Commonly Pollinated Plants|
|Giant Resin Bees||Kudzu|
|US Native Megachilids||Various native wildflowers|
Giant resin bees are pollinators, like many other bee species, contributing to the pollination of floral resources they visit. This can have agricultural and ecological impacts. However, giant resin bees are known to pollinate invasive species like kudzu, potentially causing concern for their impact on native ecosystems in the southeastern United States.
- Contribute to the pollination of plants visited
- Maybe a potential resource for agriculture and pollination of some crops in North America
- Pollinate invasive species like kudzu
- May compete with native bee species for essential nesting resources
Over the years, our website, whatsthatbug.com 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 – Fire-Tailed Resin Bee from Australia
Subject: wood boring wasp?
Location: brisbane Australia
March 23, 2014 12:40 am
Hey bugman just wondering what this is. Has been boring into wood for years and we’ve never known what it is
Signature: wood boring wasp
This is a Bee, not a Wasp, and we quickly identified it as a Fire-Tailed Resin Bee, Megachile (Callomegachile) mystaceana, (Chalicodoma mystaceana), thanks to the Brisbane Insect Website where it states: “This is a solitary bee and build nest by resin, gum or mud in enclosed spaces such as space between folds of fabric and old Mud-Dauber Wasp nest. They will nest in drilled wooden blocks too. … This Resin Bee female builds nest in existing cavity.” If that information is accurate, something else is boring the holes that these resourceful and opportunistic Fire-Tailed Resin Bees are using as nesting sites.
Letter 2 – Giant Resin Bee
Subject: Giant bees!!!
Location: Suburbs of Detroit
July 9, 2012 5:39 pm
I have had these 2 huge lavender plants out front for four years, but this year it is COVERED with an abnormal amount of bees. Most of them I recognize as locals, but there are tons of these gigantic bees that are black and the wings look black at the ends and almost take on a triangular shape when at rest. The two pics I am submitting look similar, but may be different?
What are they and do they sting like yellow jackets (over and over) or like bees (who lose the stinger in your skin)??? I grew up on a farm and have never seen such large bees! I’m excited and nervous about them 😉
Signature: Go Blue Girl
Dear Go Blue Girl,
This is a Giant Resin Bee, Megachile sculpturalis, an introduced species from Asia that has naturalized in North America. According to Bugguide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species. Aggressive, it attacks other bees; it has been reported killing honey bees.” We do not have the answer to your stinging question, though we believe it might only be the worker Honey Bees that lose their stinger. Honey Bee workers are not individuals in the sense that a solitary bee is. It serves the hive to have a Honey Bee sting continue to deliver poison even though the bee dies. It would not be to any evolutionary advantage for a solitary bee to die after stinging.
Eric Eaton responds to stinger query.
I think barbed stingers are peculiar to social bees and wasps, or at least honeybees and some yellowjackets. So, the Giant Resin Bee could conceivably sting more than once, but in my experience solitary bees and wasps take a lot of provocation before they deploy their stingers.
Letter 3 – Giant Resin Bees
Not Carpenter Bees?
Location: Northeast Georgia mountains
July 1, 2011 2:29 pm
A group of 10 or 11 of these burrowing bees-wasps-hornets-flies hangs around a wooden bench made from a cayuco, which, in the Republic of Panama, is made from a hollowed-out tree. I brought this bench with me when I moved from Panama to the mountains of northeast Georgia. I even captured 3 groups of 3 of these guys and released them at different locations between 1 and a half and 2 miles from my porch where this bench sits. That left 2 that I know of. Within 3 hours, 10 or 11 of them were buzzing around again. I believe the captives had found their way back and rejoined the group. Huh? Although they’ve made holes similar to those of the female carpenter bees, from my research I don’t believe they are–these are too social and carpenter bees don’t have the ”smiley face” characteristic that you can see in one of the images. Besides, I have carpenter bees on my property and they don’t look like them. They’re not aggressive, as I& #8217;ve sat among them–even bumping them–without getting stung; assuming they have stingers. I could easily kill them, but I don’t do that. I was tempted to sacrifice just one to determine if it had a stinger, but I couldn’t even bring myself to do that. (No, I’m not going to capture one and hold it in my closed fist just to see if it’ll sting me.) I’m really baffled; haven’t found an image that even closely resembles them. Obviously, I’m missing something. I know someone’s thinking that I unknowingly ”smuggled” them as larva inside the bench when I left Panama. I left there 12 years ago, and these showed up only 3 years ago. Please help. Thank you.
Signature: Rob Lane
The first thing we have to say is that your action photos are spectacular. Though the Giant Resin Bee, Megachile sculpturalis, is an introduced exotic species, you had nothing to do with its importation. The Giant Resin Bees were introduced from Asia and they are now very well established in North America. BugGuide indicates: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species.”
Thank you, Daniel, for that rapid response. Had I seen any image like the ones in BugGuide (the link you provided) I’d’ve instantly recognized it. Although I said it, I didn’t mean that they actually “made” the holes like the carpenter bees do. This piece of cayuco was riddled with holes, and I did observe the “plugs” in their entrances near the end of their season. Do you think that those nine I captured and released actually found their way back?
Oh, and thank you for the comment on the action photos. I credit them to my Panasonic Lumix DMC-FZ40 set at 1/160 shutter speed with flash.
Although I said that a cayuco is made from a hollowed-out tree, I failed to mention that it’s a boat (like a dugout canoe).
For your interest I’ve included a few more images focusing on the wood of the cayuco:
This is stem of the boat; the flat part on the very bow. That hole at the upper right is cut completely through and is where the boatman would tie his anchor line. You can see traces of the resin, mud, or clay at the center of the stem.
Hi Again Rob,
We believe the Giant Resin Bees may have found their way back, but we cannot be certain.
Letter 4 – Giant Resin Bees
July 17, 2009
I put up a bee house for mason and leafcutter bees with 3/8 inch holes. The leafcutters came earlier in the year and have gone. Now some of the holes have been plastered over and two large black bees with rust colored hair are going in and out the holes. They have very large eyes with mandibles coming out very close to the eyes. Their small eyes are in line with the top of their large eyes. The thorax is black with rust colored hair along the sides and the first abdomen segment is rust colored. The second segment is black, then a thin white stripe, then the rest of the abdomen is black.
Northern most part of Lancaster Co., South Carolina
The Giant Resin Bee, Megachile sculpturalis,is an invasive exotic. According to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Recently introduced from Asia. To make things worse it turns out to be a good pollinator of another introduced invasive: kudzu.” Here is how BugGuide describes the life cycle: “The female bee nests alone and begins by preparing a cell in an existing tube or narrow cavity, using resin and sap collected from trees. Other materials such as bits of rotten wood and mud are also used in nest construction. Next she collects pollen and carries it to the nest on the underside of her hairy abdomen. After completing several pollen collecting trips, she lays an egg on the pollen ball in the cell. Then she seals it, and prepares another cell. Continuing in this fashion, one female can complete about 10 cells. If the entrance of the nesting tube is directly exposed to the outside, the tube may be noticeably sealed with a resin, wood and sometimes mud cap. After the eggs hatch, the larvae feed on the pollen and spend the winter within their cells. The larvae pupate in late spring and the adult bees emerge that summer.” North Carolina State University
Letter 5 – Giant Resin Bee
Pictures of a giant resin bee, I think
I saw a couple of REALLY large bees looking at a gap in the frame of a window. I have since filled the gap. Actually, it might be more correct to say one was looking, and when the other approached they both flew up, facing each other. Didn’t seem particularly friendly but I could be wrong about that. After i caulked the gap (at night, no bee activity) I saw this bee again the next day, hovering around looking for the gap, very confused. Since then i haven’t seen him. I found a picture that matches this on your site, over this message: “The bee is a male ‘giant resin bee,’ Megachile sculpturalis, an introduced species from Asia, sometime in the 1990s. It would help to know where this shot was taken, so as to help track the progress of this species. Females nest in the abandoned tunnels bored by carpenter bees. Eric” Here are my pics; these are crops, at 100% magnification, from larger pictures. I left the shutters in the left part of the picture for scale. Oh, location is Suffern, New York. And we have a shed with abandoned tunnels bored by carpenter bees. EXIF information is intact in the pictures, if you care. I was happy to have a “super zoom” to take these, even though I don’t see a stinger didn’t feel like getting close.
We concur that this is a Giant Resin Bee.
Letter 6 – Giant Resin Bee
There’s bees all over my vitex tree. A lot of them are this guy that I don’t recognize. I looked at your bees but still not sure. Leafcutter bee? My husband thinks it might be a hornet or mimic of some kind. Always appreciate your kind help for the ” insect challenged” here in West Tennessee.
Beth and Rick
Hi Beth and Rick,
We don’t recognize your solitary bee, but we hope Eric Eaton, who at long last has returned from Appalacia, might know the answer. Here is Eric’s speedy reply: “The bee is a Giant Resin Bee,” Megachile sculpturalis, so the submitter was right on with her identification. This species was introduced to North America from Asia in the 1990s, and has quickly spread over most of the eastern U.S. The females nest in the abandoned tunnels carved by our native carpenter bees. Eric”
Letter 7 – Giant Resin Bee
Long bee on Vitex in Athens, GA
June 11, 2010
I watch bees all the time, and I have never seen this one before. I found it on my Vitex tree on June 10th at 4pm. I live in Athens, Ga.
Oops I forgot on Long bee from Athens, GA
He was as long as a carpenter bee but nearly half as wide. I have never seen any bee with these proportions.
Your bee is a Giant Resin Bee, Megachile sculpturalis. According to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own.
Recently introduced from Asia. To make things worse it turns out to be a good pollinator of another introduced invasive: kudzu.“
Letter 8 – Giant Resin Bee
Perhaps a Saw Fly
Location: North Middle Tennessee
July 26, 2010 6:08 am
This fellow came by for a short visit about a week ago. While its overall appearance looks to me like a ”saw fly” I can’t find a matching image here or on bug guide. That makes me wonder if I am looking in the right place and maybe it isn’t a saw fly after all. Thanks for all you do and have a wonderful day.
P.S. Sorry to read about your hand, I hope it wasn’t a spider bite and is all okay now.
You have photographed a Giant Resin Bee, Megachile sculpturalis, a non-native species. According to BugGuide: “Recently introduced from Asia. To make things worse it turns out to be a good pollinator of another introduced invasive: kudzu.” We are taking antibiotics and soaking the hand in warm water with dissolved Epson Salts, and things are improving. Thanks for your concern.
Letter 9 – Giant Resin Bee
Subject: What’s this bee?
Location: North Sutton NH
July 10, 2013 8:14 am
Found this insect on milkweed with my honey bee’s. Appeared to be just resting. Has large mandible’s on the front. Never seen this one before.
Signature: NH Bee
Dear NH Bee,
This is a Giant Resin Bee, Megachile sculpturalis, and it is an introduced species native to Asia. According to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species.
Aggressive, it attacks other bees; it has been reported killing honey bees.”
Letter 10 – Giant Resin Bee
Subject: What kind of bees are these???
Location: Springfield Pa
July 5, 2015 10:34 am
Can someone please tell me what kind of bees these are? We noticed them last week and sprayed where they seem to be making a nest in the arm of our awning? We thought we got rid of them and now they are back.
When my 4 year old sees them she wont go outside:(
Thanks in advance for your help!!
This sure looks to us like an invasive, exotic Giant Resin Bee, Megachile sculpturalis, and you can verify our identification by comparing your image to those on BugGuide. According to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species.”
Letter 11 – Giant Resin Bee from Michigan
Would love ID on this bee
My son and I noticed a bee we’ve not seen before visiting our flowers this summer. I know you are swamped, but I couldn’t find one like it on your bee page. It is over 1.5″ long. We saw a smaller variant also, about 1″, but I couldn’t nab a picture of it. Your site is our favorite on the Web. I’m glad and sad you are so popular.
Scott Williams and Kyle Mink
Hi Scott and Kyle,
Thanks for the compliment. We wish you had provided us with global coordinates. We are checking to see if Eric Eaton recognizes this bee which has us baffled. Eric quickly wrote back: “The bee is a male ‘giant resin bee,’ Megachile sculpturalis, an introduced species from Asia, sometime in the 1990s. It would help to know where this shot was taken, so as to help track the progress of this species. Females nest in the abandoned tunnels bored by carpenter bees. Eric”
D’Oh! Sorry! We are in Ann Arbor Michigan. My son is convinced it is a hybridized African bee — finally making it up this far north. He normally is on target ID’ing insects (ever since the age of 3, and he’s 11 now). Thanks!
Scott and Kyle
Letter 12 – Possibly Pine Resin Droplets
Subject: Hard Ball
September 21, 2014 2:25 am
Hello. I just was wondering what are these small,hard, orange balls found on carpet? If they’re insect related
Signature: Raquelle Alexander
We do not believe these droplets are insect related. They appear to be resin droplets to us. Check if the ceiling beams are oozing resin.
Letter 13 – Sculptured Resin Bee
Subject: Tube Nesting Wasp?
Location: Western North Carolina
August 19, 2015 9:37 am
These rather large (1 inch plus) wasps (?) are busily nesting in the larger of my Mason and Leafcutter Bee nesting tubes, and they seal the end of the tube with a mud plug.
This is an introduced Giant Resin Bee or Sculptured Resin Bee, Megachile sculpturalis, and it belongs to the same family as your native Mason and Leafcutter Bees. According to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species.”
Letter 14 – Sculptured Resin Bee
Subject: What is this bee looking bug?
Location: New York, 10960
July 8, 2016 10:07 am
I know there are carpenter bees eating away at my deck. But the other day I saw this guy just lurking around. It doesn’t look like the others. The thorax is much longer than the C-bees. And the black circle, by where the wings attach to the body, surrounded by the gold fuzz is much much larger.
Image 1 is the bug in question
Image 2 is the carpenter bee
The Bee in question is an introduced Sculptured Resin Bee, Megachile sculpturalis, and according to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species.” Thanks for including the image of the Eastern Carpenter Bee for comparison.
Letter 15 – Sculptured Resin Bee
Subject: Rusty red-furred bee. Ridged flat back.
Geographic location of the bug: Fredericksburg, Virginia
Time: 01:15 AM EDT
Your letter to the bugman: I saw this bee on an agastache flower in my backyard. I looked at your guide and it seems to be a resin bee? It’s gorgeous.
We used to have carpenter bees out back (deck) but now they’ve sawed our front porch. You say that the resin bees move into already established holes…………………….
How you want your letter signed: swarner
You are correct that this is an introduced Sculptured Resin Bee and according to BugGuide: “They are opportunistic and nest in existing wooden cavities, rather than excavating their own. Effectively pollinate kudzu, another invasive species.”