The Giant Resin Bee

Feb 23, 2020

The Giant resin bee (Megachile sculpturalis) is an invasive species from Eastern Asia accidentally introduced to the United States in the mid 1990’s. It is now present in most states East of the Mississippi river and is expanding Westward. It has been observed pollinating 43 different native species but it especially likes to pollinate the introduced plants from Asia (apparently including Kudzu). Much of the info in this article is from the taxonomic paper on the Giant Resin Bee in the biodiversity data journal and from the department of entomology of the University of Florida (UF/IFAS).

The first specimen of Giant resin bee was collected in 1994 in North Carolina. It is suspected that the bee was introduced through international trade. The range rapidly expanded across North America from the original location, reaching southwest to Alabama by 1999, north to Canada by 2002, northwest to Wisconsin by 2004, northeast to Maine by 2008, and westward to Kansas by 2008.  By that time almost all states East of the river had been colonized. I started to observe The Resin bee in 2016 in Mississippi and its population has been growing since then in Hudsonville. The western edge of its range seems to stretch now to western Texas, Oklahoma, Kansas, Nebraska, and South Dakota, areas of the western coast, along with sections of Mexico. This species has also been introduced into Europe in the mid 2000’s, through the port of Marseille, and is currently established in France, Switzerland, and Italy.

The Giant Resin Bee is a Megachile (Callomegachile), easily differentiated from native bees by a large narrow elongated body. US native Megachilids, such as leafcutter bees, are considerably smaller than the giant resin bee, ranging in size from 5 mm to 24 mm. Female Resin bees range from 22 – 27 mm, while males are considerably smaller at 14 – 19 mm with a distinctly wide yellowish “moustache” on their lower face. The large cylindrical body is typically black and yellow-brown in color. The head is dark with yellow-brown setae (hairs). These golden hairs can be found on the thorax and the first segment of the abdomen. The female has a more pointed abdomen while the male’s abdomen has a blunt edge. See picture above of a male with its square abdomen.  The moustache of golden hair is visible on the picture below. Giant resin bees have smoky-colored wings that contain dark marks near the edges. Their wings, while resting, are often held in a V shape.

Megachile sculpturalis are solitary bees that do not form colonies. They are nevertheless gregarious and females build their nests in the same area as other females. They are known to be tunnel nesters, however I have found one nest in a large cavity between two boards and the nest was not organized as a tunnel (see picture below). The females create their nests in narrow grooves in tree cavities, crevices, downed logs and other debris sometimes used by other bee species. They are known to displace native carpenter bees (Xylocopa spp.) from their cavities in order to nest in them. During the summer months, female Megachile sculpturalis begin constructing brood cells of wood particles and mud, very similar to those of the native carpenter bee (Xylocopa virginica). They will use existing carpenter bee cavities in order to lay their eggs because their mandibles cannot chew through wood to create cavities of their own. They will use other material with pre-existing cavities as nesting habitat such as rotting wood. After several pollen collecting trips, the females form a pollen ball containing pollen and resin in each brood cell and lay a single egg on the pollen ball. She will seal the cell using a mixture of wood particles, mud, or resin. After the first cell is sealed, the bee will repeat the process and lay another egg within a separate brood cell. The female can make as many as 10 cells per nest. Larvae remain in their cells and feed on the pollen balls. They will consume this food throughout the winter. The larvae will pupate during the spring and the adults emerge in early summer. This female fills in a cavity with mud and resin. The bee hotel was mainly used by a Giant Resin Bee. The pointy abdomen, different to the squarish tip of the male abdomen is visible on the picture.

This female giant resin bee was found dead next to her nest built between two boards. The nest is not organized in the form of a tunnel but in the form of a fan starting from the angle of the board. It is made of solid resin.

Although their large appearance may make them intimidating, they are largely harmless. The males are unable to sting, and the females, although able to sting, are not aggressive and usually fly away from humans. The overall ecological impact of this bee has been considered benign, since no drastically negative or positive outcomes have been detected by their presence thus far. They are known to pollinate up to 43 different species of plants in the US and do exhibit preferential pollination of plant species from their native habitat. The giant resin bee has been observed to leave puncture marks on the petals of two types of flowers, the everlasting pea and the Japanese pagoda flower. This is a helpful visual marker for researchers studying what plants the giant resin bee visits. This behavior does leave a permanent mark on the flowers, and in other species, a mark like this could have a negative effect on the pollinating ability of the flower.

These bees may negatively affect a native carpenter bee, Xylocopa virginica. The carpenter bees are known to chew long narrow cavities in the eaves of homes, which the giant resin beeswill use as nest sites. Because of this, Megachile sculpturalis may actually compete with Xylocopa virginica for nesting habitat.

The Lemy hive

Feb 17, 2020

Mississippi climate is not for the faint hearts. While winters are mild, the amplitude of temperature can read more than  40 degrees over the day. Summers may customarily culminate over 100 Fahrenheit, the air saturated with moisture. As a consequence, bees may spend a lot of energy abruptly heating up the hive or cooling it down in emergency. The poorly insulated hives do not do well and if the walls are thinner than 2 inches, the bees will beard en masse. Repurposing conventional hives adapts them to the bees needs: insulation, shape and volume. It is also possible to add a super if the season is bountiful, making the hive still productive for the bee keepers interested in honey.

The first step consists in setting a bucket wrapped in a plastic tarp to a bottom screwed to the box and pour plaster of Paris in the open volume. The video in the article “refitting a Warre hive” is self explanatory. The plaster hardens in a matter of hours and will cure over several days. The bucket can be removed the next morning, using a hammer to push it out. One Langstroth deep is about 42 liters, which is the average volume of a hive in a hollow tree in the wild. Usually a complete Langstroth hive is made of two deeps and one super pushing the volume to 100 liters, way too large versus what the bees will look for in Nature. Repurposing a Langstroth with plaster will reduce the volume of each deep to about 15 liters. Therefore, 2 deeps will contain 30 liters. A few liters are added with a bottom shaving box; a super would add 15 to 20 liters on top. Bees will thrive in 30 to 35 liters, they will also keep on prospering over years in a volume as snug as 27 liters, at least in the North of Mississippi. I recommend volumes between 30 and 40 liters for several reasons:

1- The control of temperature is easier for the super-organism.

2- The bee colony is rather small and in case of disease it will collapse quickly limiting the horizontal propagation.

3- The size of the colony shrinks early in the season and the queen will stop laying eggs and the comb is loaded with honey.

4- There may be an optimal ratio bee population to honey stash for winter and it feels like a 35 liter hive is right at this optimum, the stash will be full and the population sized to it.


The top bar hives are set upside down on the top box so their shape can be outlined with a sharp blade.

The grooves are carved so the triangular section of the bars can fit in, with the top of the bars flush to the plaster surface.

The surface of the inner chamber can be very slick as the plaster in contact with the plastic tarp forms a glassy surface. I use a hard metal brush to create vertical grooves similar to the grain of wood so the bees can cling but also can propolize as they see fit. A propolized chamber is necessary to the good health of the bees, it also makes the chamber water proof, conveying condensation in winter.

I like to add a bottom box to the two supers. This box is a super equipped with a tight bottom mesh to hold wood shaving. The wood shaving combined with the dejections and the moisture of the hive will eventually favor a biome of microfauna, fungi, bacteria or yeasts. This environment may be beneficial to the bees. There have been few studies on the matter, but I would believe that this box would be similar to the bottom of the cavity in a tree. Here, I created a floor board to support the bees walking into the brood chamber. The surface of the shaving is below the surface of the board. The board is slightly sloped up into the hive so the height at the rim of the cylinder is equivalent to two bees passing each other, one on the ceiling and one on the floor board.

The floor board is long enough to drive the bees within the hollow of the chamber, it is visible from above on the below picture.

The entrance is a notch of 1o centimeters flush with the outside landing board.

The second deep comes on top of the lower deep. To keep the Langstroth design, I use in this example the top telescopic board covered by an insulated roof. A quilt box similar to the one in a Warre hive can also be an option, in this case a flannel would also be laid over the top bars, a mosquito net can be inserted below the flannel so the bees  cannot chew on the fabric. You can refer to the video about repurposing a Warre hive for that matter.

The hive is ready. It is a minimum work that takes about one hour to prepare and pour the plaster and 60 to 90 minutes to build the bottom box. If the bottom box is too much work, a conventional entrance board of a Langstroth hive will work. In this case a bottom mesh with a sliding board underneath allows to count the dead mites, which is not possible with a shaving box.

Refitting a Warre hive

Feb 01, 2020

Honey bees fare well in a Warre hive. However, commercial models may be built too thin and the bees waste a lot of energy controlling the inside temperature, in Winter and in Summer. These hives may be modified by molding a cylinder of plaster in the body.

The following video shows the steps to get the project complete. It takes about one hour the first day and 90 minutes the following one, once the plaster has cured. Bees usually build in one season about one warre box and a half, they may swarm the second season and would build in a third box nadired below the top two. Each box contains 20 liters, therefore in the first season the bees will build in about 30 liters, maybe a bit more if the conditions are propitious. The cylinder molded in the boxes presents a volume of 13 liters, it is therefore recommended to stack 3 boxes for the first season. Each box becomes very heavy, about 40 pounds without the bees and the combs, so nadiring the structure can be difficult. If some honey wants to be harvested, one can add a standard warre box on top that will be collected. I leave my hives live their life, I don’t harvest.