Learn About Leaf Cutter Bees

Learn About Leaf Cutter Bees



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By: Stan V. Griep, American Rose Society Consulting Master Rosarian, Rocky Mountain District

By Stan V. Griep
American Rose Society Consulting Master Rosarian – Rocky Mountain District

Do you ever see half moon-shaped notches that appear to have been cut out of the leaves on your rosebushes or shrubs? Well, if you do, your gardens may have been visited by what is known as the leaf cutter bee (Megachile spp).

Information About Leaf Cutter Bees

The leaf cutter bees are seen as pests by some gardeners, as they can make a mess of the foliage on a favorite rosebush or shrub by making their half moon shaped precision cuts out of the leaves. See the photo with this article for an example of the cut outs they leave on the leaves of their plants of choice.

They do not eat the foliage as pests such as caterpillars and grasshoppers will. The leaf cutter bees use the foliage they cut out to make nest cells for their young. The cut piece of leaf is formed into what might be called a nursery chamber where the female cutter bee lays an egg. The female cutter bee adds some nectar and pollen to each little nursery chamber. Each nest cell looks a bit like the end of a cigar.

Leaf cutter bees are not social, like the honeybees or wasps (yellow jackets), thus the female cutter bees do all of the work when it comes to rearing the young. They are not an aggressive bee and do not sting unless handled, even then their sting is mild and far less painful than a honeybee sting or wasp bite.

Controlling Leaf Cutter Bees

While they may be considered a pest by some, keep in mind that these little bees are beneficial and essential pollinators. Insecticides are not usually all that effective to prevent them from making their cuts to the foliage of the rosebush or shrub they choose as they do not actually eat the material.

I advise those that are being visited by the leaf cutter bees to leave them alone due to the benefits we all reap because of their high value as pollinators. Leaf cutter bees have a large number of parasitic enemies, thus their numbers can vary greatly in any one area from year to year. The less we as gardeners do to limit their numbers, the better.

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The Leafcutter Bees Life Cycle.

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Leafcutter bees life cycle. The bee obtaining pollen on cosmos flowers, as well as recognizing their breeding habits to save the bees.

The Leafcutter Bees Life Cycle.

A beautiful example of, the yellow bottom of abdomen, of a leafcutter bee, on the garden cosmos flowers. I found they have a larger body than a normal honey bee.

How they breed and obtain pollen.

Here this Darker species black and white striped is just one of the species found.

The bee is very similar to a normal honey bee, slightly a little bit bigger. Their lower abdomen is yellow.

Very distinctly different to the normal bee. They are solitary bees and do not have a queen bee or a hive.

They don’t produce honey nor bees wax.

How they breed.

In the wild they build their nest in holes in dead trees or in the tubes of reeds, spinning the pieces of leaves in a tube, and sealing them off with small pieces of cuts of leaves.

Below Bee carrying pieces of leaves.

The female leafcutter bee divides her leaf tunnels in reeds into chambers and divides them up and then lays her single egg, supplies some pollen/nectar mix as food for the egg laid there. Then closes it up with thin piece of leaf. She continues in this way till she fills the site she obtained. Sealing with a few pieces of leaves to protect against predictors.

The larvae hatching eats the food and stays in this tube for a period of hibernation.
It will spin a cocoon until it pupates, hatches. Normally in spring or early summer. They emerge an adult bee in 6 to 8 weeks.

Below Rolled leaves to make a tunnel for egg laying. Leaf cutter bee nests.

Below Leaf cutter bees cocoons.

Breeding cycle continued.

The bee will give the female eggs she lays more pollen as the female is larger than the male.
The male egg is provided with less pollen to feed on. As male bee is smaller. The male bee
hatches first and once they mate with the females they die.

Female bees survive for several weeks and build their new nest again

They have a good temperament and do not sting as bad as a normal honey bee.

This is the tunnels they breed in see as below.

The first tunnel represents how the leaf cutter bee builds, then the resin bee, then the mason bee with mud separations.

Pollinators

The leaf cutter bee is a very important and efficient pollinator bee.

This bee is overlooked by bee keepers as it doesn’t produce honey or bees wax. An individual bee will visit a greater number of flowers than a normal honey bee, but are so much messier.

They lack the basket to keep the pollen secure and it drops off their abdomens, causing cross pollination of the flowers.

The bees are very hard workers and readily pollinate during lower temperatures, working longer hours.

So much more efficient pollinators than the honey bee. They are said to be the new pollinators on the block.

A beautiful view of the yellow abdomen of the leaf cutter bee. obtaining pollen on the cosmos flower.

These leaf cutter bee was on my garden cosmos flowers in Vilcabamba, Loja, Ecuador.

A butterfly on a cosmos flower.

So the next time you come across some tubular leaf things, you should know that those are bees cocooned inside and are called the leaf cutter bee.

This site below tells us a how to make homes for the leaf cutter bee and how to preserve them during hibernation.


Surely by this time of year, you have seen the mysterious circular- or oval-shaped holes in the leaves of plants in your yard. These are formed by our friends, the common leafcutter bees. They are solitary bees in the large genus Megachile, in which there are almost 1,500 individual species.

Leafcutter bees are smaller than honeybees. They don’t collect pollen on their legs like honeybees or bumblebees – they use hairs on their abdomen if you see them, you might notice the bright yellow color of their tummies. I find the leaf holes now in summer but I’ve never managed to actually see the bees on flowers until fall. Leafcutter bees are super-productive pollinators. In greenhouse or netted experiments, USDA-ARS has shown that that 1 alfalfa leafcutter bee can do the job of 20 honey bees.

The bees nest in soft, rotting wood or in pithy stems like those of roses or elderberries– they will not damage your house. In spring, you could even set out elderberry or lily prunings for them to use as nests. They use those little leaf pieces to make individual cells for each egg in the nest. Leafcutter bees will use many kinds of leaves but prefer soft, smooth leaves such as those from: rose, green ash, lilac, and Virginia creeper.

The leaf injury is usually just a curiosity. However, if you happen to live in a rural area with few leaf choices and abundant leafcutter bees, they could remove a lot of leaf tissue and hurt certain plants. Insecticides WON’T help since the bee is not eating the leaf you will have to protect the plant with netting. It almost makes it tempting to leave more of those ash seedlings growing around the flower beds, doesn’t it?


BeeGAP membership - an exciting journey

Experience how the wild bees hatch, diligently collect pollen and create their offspring ready for the following year.

With a BeeGAP membership you will receive a starting population of leafcutter bee cocoons in the spring-summer. These bee cocoons are placed inside your bee house to incubate as the weather warms. Ensure your bee house is in a sunny location.

The leafcutter bees will being to hatch throughout the summer. A few days after the males and females leave the nest, and the mating season begins. Leafcutter bees are completely harmless, gentle natured and safe around children & pets.

Three

After the mating season the females build their nests. They collect pollen and nectar for their offspring, provisioning it all within a small cocoon. During this time the bees pollinate wild plants, fruit trees & veges within a radius of up to 800 meters.

Once a nesting tunnel is full, the female will close off the end of that tunnel using either clay, mud, plant fibres or leaf pieces - leaving inside her next generation of offspring. She repeats this process many times throughout the spring-summer.

In late April / early May, it's time to open up the BeeHome, check on our bees and start the over-wintering process. This only takes a few minutes each year and we have an quick easy to follow video with instructions for this.

Through spring-summer all active BeeGAP members will receive their new allocation of leafcutter bees ready for the next season. The cycle repeats - with you helping raise wild solitary bees & gaining pollination benefits in your garden.


Making a home for Leaf-cutter bees

By Suzanne Rex, Conservation & Volunteer Assistant

I began working at the Bumblebee Conservation Trust in February 2016, answering a number of enquiries and helping out in the office. Starting this job with little knowledge about bumblebees and other pollinators, I have been required to research a great deal of information for email replies. This opened my eyes to the huge diversity and importance of pollinators. One group of bees which I found particularly interesting were Leaf-cutter bees, which is why I decided to write a blog about them.


Leaf-cutter bee ( Megachile sp . ) in a nest. Photo: Anne Donelly

As well as the social living bumblebees and honeybees, there are over 225 species of Solitary bees pollinating the UK. They are called solitary bees as they have no social caste and basically fend for themselves and their offspring. Leaf-cutter bees belong to the Megachilidae family, and are a fantastic pollinating group for a variety of fruit, veg and other plants including wildflowers.

Some species, like the Silvery leaf-cutter bee (Megachile leachella) and the Coast leaf-cutter bee (Megachile maritima) can be found nesting in groups called aggregations, although each female tends to their own nest cells. However, most species choose to nest in existing cavities on their own. Leaf-cutters have been found to nest in a variety of places such as dead wood, hollow plant stems, cavities in walls and occasionally in the soil. Commonly found in gardens, these bees are widespread across the UK, though they have a smaller presence in the north.

One of the most common species of Leaf-cutter bee is the Patchwork leaf-cutter (Megachile centuncularis). Patchwork leafcutters look similar to honeybees, though the females have a patch of hair beneath their abdomen called a pollen brush. The pollen brush is used for storing pollen, as opposed to most other bees which store pollen in pollen baskets on their hind legs. Intriguingly, some Leaf-cutter species including Patchwork leaf-cutters lift their abdomen up into the air while feeding see this video to watch this distinctive foraging behaviour. However, they are probably best known for their trick of cutting neat, semi-circular pieces out of rose and wisteria leaves to take to their nests. These bees will grasp the leaf cutting and carry it underneath their body to their nest. The Patchwork leaf-cutter will glue the overlapping pieces of leaf together with saliva to use as lining, in order to build individual cells for their eggs which are sealed off by more pieces of leaf. Within each cell, the egg is provisioned with pollen to provide the hatched larvae with essentials to grow. This pollen can come from a variety of flowers including legumes like runner beans, as well as berry flowers like brambles. The larvae will then pupate into adults in autumn and hibernate inside their cells over winter.

left Black-headed leaf-cutter (Megachile circumcincta) male. Photo: Steven Falk
right Patchwork leaf-cutter (Megachile centuncularis) cutting a leaf. Photo: Bernhard Plank

Make a home for the bees

Like many solitary bees, Leaf-cutters can be limited by the amount of available nesting habitats. The good news is that this is something we can all easily do something about – by creating a bee hotel. Leaf-cutters and other solitary bees are great for pollinating your fruit and veg, so why not help them out and entice those that like to nest in cavities into your garden? Bee hotels are great to watch, provide lots of entertainment and are available to buy in most garden centres. You can also make one yourself which is cheap and easy. For 5-star accommodation all you need to do is find an untreated block of wood and drill holes of varying diameters into it (2-10mm), but not all the way through the wood. Try and make the holes as smooth and splinter-free as possible, as splinters can damage their wings. It is also important that rain does not get into it so the gaps should be created at a slight incline. The hotel should then be propped up or mounted onto a sunny, south facing wall and at least a metre off the ground. Another option is to find sections of old, hollow bamboo canes (around 20-30cm long). Tie the bamboo sections together, or place them into a plastic drinks bottle with both ends cut, and hang them horizontally in a sunny and sheltered position.

Many bee hotel designs and ideas can be found on the internet to help. It is best to replace the holes in your hotel every two years, as this prevents the build-up of fungus and parasites. Patchwork leaf-cutter can be seen between mid-June to early September, so if you can set up a home for the bees soon, you may find it is used this year. If not, it will be ready for next year’s bee season in spring!


Bee hotels. Photo credit: storebukkebruse. CC


When your Backyard Pollinator arrives, the leafcutter bees are dormant. What happens next?
Read this description of the 8 steps of the lifecycle of a leafcutter bee to find out more!

Illustration by The Watrous Manitou

1. In our warehouse the leafcutter bees are kept at a temperature between +1C and +15C. Within this temperature range the leafcutter bees are in sustained dormancy. The bees are in this state upon shipping and arrival to your doorstep.

2. Incubation and Metamorphosis:

  • Incubation is initiated when the temperature of the Backyard Pollinator goes above +15C for a sustained period of time.
  • Incubation can be done artificially by keeping the bees inside your home until adult bees emerge
  • Incubation may also be done naturally by placing the bees outside when the minimum temperature is above freezing (0C) and daytime temperatures reach +20C.
  • Metamorphosis is the change from larvae to adult bee. Briefly, the larvae will change shape, develop legs, a head, thorax and abdomen. Next the eyes will turn pink, then red and finally darken to black (female) or green (male).
  • Once the eyes have darkened the body color deepens.

3. The bees finally reach maturity with fully developed wings, eyes, claws, antenna, hair, etc and are ready to emerge.

  • Cutting their way out of their cocoon with their mandibles, the new adults emerge. At this stage they are ready to fly into the world to find food in the form of nectar and pollen. This food gives them enough energy to grow just a bit more. The new bees will find shelter in the empty holes of your Backyard Pollinator.

4. Leaf cutter bees mate soon after emergence. They join tail to tail and mating is complete.

5. A male leafcutter bee’s main purpose is to fertilize females. Once this task is complete they soon die.

6. Female bees live 5 to 8 weeks. In this time they collect food and leaf material to make cells. An egg is laid in each cell and she may create up to 20 cells with eggs. Females are only 33% of the population so you need three larvae to replace one female bee.

7. In a short time the females fly their wings off and die. The two generations only coexist for a short time.

8. The new egg hatches as a larva to find a large cache of pollen and nectar paste, which is the true start to a generation.

  • The bee larvae eats the food paste and grows for approximately 20 days, eventually consuming all its food source.
  • After a short time without food the larvae knows it is time to spin a silk cocoon inside the cell which now only contains a larvae.
  • The silk cocoon is a marvel unto itself, being waterproof and semipermeable to gasses.


LEAFCUTTER BEES (Megachile)

The amazing handiwork of the Leafcutter Bees makes them one of the most fascinating bees in Australia! The Leafcutter Bee snips a neat circle or oval from a leaf. She will use these leaf pieces to weave tiny cradles for her eggs inside her nest burrow.

Our Leafcutter Bees are in genus Megachile and range in size from about 6 to 15 mm. They belong to the family Megachilidae and are found all over Australia.

Erica Siegel of Queensland kindly contributed the following amazing photographs about Leafcutter Bees in action:

Above: Erica Siegel captured this fantastic close up shot of a Leafcutter Bee in the process of snipping a piece from a leaf! Notice this bee's powerful mandible or jaw that the bee uses for cutting the leaf pieces. Leafcutter Bees carry pollen back to their nests by packing it on the array of stiff bristles that you can see here underneath the abdomen.

Above: Another beautiful shot by Erica Siegel of a Leafcutter Bee in action. Leafcutter bees use these leaf pieces to weave cells for their young inside their nest burrows.

Above: the characteristically uniform cuts made in soft leaves by Leafcutter Bees.

"Peter O' captured this furry Leafcutter Bee snipping a leaf piece for her nest:

Above: Leaf cutter bees grasp the leaf pieces with their legs to carry them back to their nests.

Another wonderful Leafcutter photograph contributed by 'Peter O':

Above: notice the Leafcutter's characteristic thick pad of bristles under the abdomen.

The Leafcutter Bee always cuts extremely neat circles and ovals, unlike caterpillars which leave irregular holes in leaves.

They take the pieces of leaf back to their nests which are in burrows in the ground or in a narrow crevice. There they weave the leaf pieces into a cylindrical brood cell for their young.

Above: this neat brood cell was woven by a Leafcutter Bee for her young in her nest in a hollow bamboo tube. She stocked the cell with nectar and pollen, before laying a single egg in the cell and sealing it up.

Above: this Leafcutter Bee is snipping a circular piece from a rose leaf. This excellent photograph was contributed by Shirley Woods.

Whilst rose leaves are one of the Leafcutter's favourites, other soft leaves that they like to use include Buddleja (above) and wisteria.

Above: Thank you to Noah Hunt for this wonderful action photograph of a Leafcutter Bee returning to her nest in a limestone wall with a pink leaf!


Watch the video: Mason Bees For BEGINNERS! - Learn how to start Mason Bees!