The carpenter bees, a large solitary bee
Are you familiar with solitary bees ? They make up 90% of all bee species. Solitary bees are not part of a colony. They do not have a queen and do not produce honey. Most of them are harmless and do not have a stinger because they do not need to defend their honey. These wild bees are not very visible and we neglect them in our gardening by destroying their habitat. So let's find out more about one of these solitary bees: the carpenter bee !
Who is the carpenter bee ?
Latin name : Xylocopa violacea
Order : Hymenoptera
Family : Apidae
Size : 2 to 3 cm
Location : roof structure
Period : spring, summer
What you need to know about the carpenter bee
Although it belongs to the same Apidae family as bumblebees and honeybees, it does not have the same lifestyle. Unlike the aforementioned species, which live in colonies, the carpenter bee has no organised social life and is solitary by nature. Males and females only meet in summer during the breeding season.
Its presence generally indicates a problem with dampness in your roof structure, as this insect can only settle in wood whose mechanical strength has been weakened by the presence of fungi.
The breeding period takes place in late spring (May-June) when outside temperatures rise. Shortly afterwards, the insect digs tunnels or creates existing galleries in the wood (branches, trunks, reeds, beams, wood-eating insect galleries, etc.) to lay its eggs. The galleries consist of boxes where food (pollen and nectar) is stored to ensure the proper development of the future larvae. Around ten eggs are produced and laid (one per chamber).
The life cycle of a carpenter bee
The life cycle of Xylocopa violacea consists of 4 stages and lasts around 7 weeks :
1 - Egg laying and hatching
This phase takes place in the wood galleries dug by the female. Each egg is deposited in a chamber providing a food supply of nectar and pollen for the future larvae.
2 - The larval stage
The larvae are off-white in colour and measure between 2 and 3 cm in length. They are fairly large and noisy.
3 - The chrysalis
Before becoming an imago, the carpenter bee passes through the chrysalis stage.
4 - Adulthood
At the end of the summer (generally at the end of August), the young adults leave the nest and fly away.
Damage caused by the carpenter bee
The only sign that it is present are small piles of wood shavings, which it does not ingest.
The carpenter bee burrows mainly in diseased or dead wood, but it can also cause damage to roof timbers, window panelling, garden sheds, garden furniture and any untreated wooden object exposed to the elements.
You can offer them shelter by building shelters from reed stems, which they like.
Leave a log of wood at the bottom of the garden, and it may be selected as a bee house.
Should the carpenter bee be eliminated ?
This insect is not dangerous. And bees are protected insects, so we won't be directing you towards products to eliminate them.
Our advice : Remove the source of the damp, replace the affected wood and you'll see that the carpenter bee will disappear on its own.
Why and how to encourage the carpenter bee in the garden ?
The absence of dead wood in your garden can encourage this bee to establish its nests in the wood of your house, and can therefore cause problems. You can provide them with old pieces of wood in a sunny corner of your garden. You can also build an insect hotel and set aside a space with planks and logs for the bee to dig its galleries. Place them high up so that the bee can access them in flight.
The carpenter bee is an ally of the garden, a pollinating insect. It pollinates mainly orchard trees and vegetable garden plants, but also wild flowers in meadows and ornamental beds. So, by encouraging the carpenter bee and recreating its natural habitat in the garden, you can contribute to biodiversity and a balanced garden !
Frequently asked questions about bees, carpenter bees and bumblebees
Q: How can I protect my holiday home from swarms of bees ? Twice now they've taken up residence behind a shutter, and naturally they damage the wood with their honey, which is dangerous for us.
A: I understand, and unfortunately this is very common on second homes. Bees, wasps, hornets and we have no solution to offer you to prevent them from taking up residence when you're away !
Q: I live in the middle of the countryside and I have some charming neighbours with 32 beehives overlooking our pleasant garden. Unfortunately, the bees don't like this approach and our happy place has turned into a real nightmare. They're aggressive and we can't enjoy our garden any more, even without a swimming pool !
A: Bees are protected insects and they look for water to drink. We can't offer you any solutions !
Q: I have a swarm of bees in my fireplace between the brick and the chimney. How can I get rid of them without letting them into the house? I've had a few get into my basement because my fireplace is downstairs. Is it dangerous to heat the fireplace or could that make them leave? Would it be better to wait until winter ?
A: I'm going to have a hard time answering your question, as it's difficult to locate the swarm in your flue! One thing's for sure: when winter arrives, they'll move into their winter quarters and sleep there for several months, and if you intervene, they'll all die. To make them leave and get some peace of mind, you close your flue with a mosquito net and burn some chimney sweeping compound, which gives off a thick smoke; those that don't leave will probably die.
Q: What product should I use to get rid of the carpenter bees that have taken up residence in the wooden beam of our terrace. In the morning we find a lot of sawdust on the tiles. I should point out that in 1999 we called in a company specialising in the treatment of carpentry with an injection of this product: XYLOPHENE SOP 2000 ESE CERTIFIED CTB P+, but every year in the heat they come back.
A: I'm not sure that our insecticide will solve your problem. Carpenter bees generally only attack wood that is fragile (moisture attack and fungi). You should check with a nail whether your wood is hard or "soft".
Q: I'd like to know whether your 4J 10% insecticide is effective against carpenter bees. If I follow your advice, I'll have to change my roof. The problem is that it's very expensive.
A: Carpenter bees are not "dangerous" insects, but it's true that they dig nests in soft or damaged wood, which can be a problem if you have a lot of them! 4J insecticide diluted to 10% kills hornets. So there's no reason why it shouldn't kill this type of insect.
Q: Bumblebees have taken up residence behind the plasterboard in my child's bedroom. I've broken part of the wall, but I can only see that they're there without getting to the nest directly. And the roof is too high to block access. Even though it's not dangerous and they're useful, I'd like to get rid of them or prevent them from continuing to develop the nest. What products do you offer to repel or destroy bumblebees ?
A: As a repellent, we don't yet have any products for this type of insect. As an insecticide, a product like Pistal is very effective, but its range is only a few metres.