Protective nets and fabrics for parasitic protection and beehive ventilation systems.
What you will learn here:
- Why are there protective nets on the ventilation holes of beehives (bumblebees)?
- why are they so important
- Why is it necessary to pay attention to the selection of the soil material?
Last updated: 7/1/2021
The importance of nets for a bumblebee hive
- In addition to the necessary flap on the comb serving as an entrance for bumblebees, each hive must also contain a ventilation hole. Hives without a ventilation hole do not allow air exchange, the accumulation of carbon dioxide in them shortens the life of the colony, and the increasing humidity in the hive, which has nowhere to go, can lead to water condensation. This also happens when the keeper opens the hive, as there is a sudden change in temperature and a shift in the dew point. The condensation can then soak the lining or form puddles until the water level sticks to the bottom. In addition, an unventilated hive is more susceptible to mold, the walls degrade more quickly and the hive loses its properties more quickly. Any additional hole in the hive, however, represents an easy entrance for parasites, including the most dangerous ones such as Melittobia acasta and Aphomia sociella.
- Many commercial hives and hives produced by beekeepers cover these openings with nets. These should generally consist of at least two (optimally three) layers. The outer and inner nets are designed to resist damage from bumblebees and larger parasites or predators. Aluminum nets are most often used because many plastic nets have been shown to be able to bite through such nets. The most important thing is the middle net, which should form a barrier to the penetration of even the larval stages of parasites. Many of them are able, if stopped by the outer nets, to lay eggs here and the larvae will then overcome the barrier. The purpose of protective outer nets is only to protect the key middle one from damage. To prevent this from happening, the outer nets must not touch the middle one.
Hive ventilation - parasite eggs (here flies) laid on the mesh of the ventilation hole
Photo O.Hercog 2018
Selection of mesh materials
For a network to be meaningful, it must fulfill three fundamental tasks:
- dense enough to stop even the most dangerous parasite such as Melittobia acasta. Unfortunately, the incidence of this wasp is increasing in farms.
- Despite its density, continue to ensure sufficient ventilation of the hive.
- Resistance and stability of the material in ventilation conditions. Resistance of the material to the movement of larvae or adult parasites that penetrate it even through external protective meshes.
It is not easy to meet these three points and many commercial products do not even come close to the required parameters. The ventilation hole thus remains an entrance gate for parasites or ceases to fulfill its function. However, the breeder, especially the beginner, relies on the manufacturer and is then disappointed with the failure of breeding. Many attempts to solve the mesh using various materials available in the household turn out the same way - for example, a frequently used material for this is Organza.
The work and task of our group was to find material that would meet the required points as much as possible.
Testing method and selection of materials
The Czech commercial network offers domestic products Uhelon and Ulester with very high quality workmanship and precision of the screens. These screens therefore meet point 3 – the requirement for the resistance and stability of the screens. These are 100% polyamide (uhelon) and 100% polyester (ulester) fibers. There are a huge number of types of these fibers, which differ from each other in the size of the mesh and the strength of the fiber. We therefore took the frequently used material Organza as a reference sample because of its well-known and breeder-verified breathability. Since the parasitic wasp can pass through Organza, we excluded all screens with a larger mesh size than Organza.
In addition to the requirement for mesh size and tensile stability, emphasis is also placed on maintaining the breathability of the material so that the basic function of the holes is not disrupted - i.e. ventilation and heat and moisture removal.
Potentially suitable materials were therefore tested for their breathability in a certified laboratory of the Faculty of Textiles of the Technical University of Liberec. The testing was carried out using the FX3300 Textex device. Standard: ČSN EN ISO 9237 Pressure gradient: 100 Pa Test area: 20 cm2. The breathability of Organza was given as a reference value.
The pore size of Organza was measured using image analysis on three images in the same place.
Microscopic observation
of the parasitic wasp melittobia acasta on an organza textile fiber
, photo by Kučera Karel
microscopic comparison of individual sieves
photographs Kučera Karel
Example of measuring areas on organza,
Faculty of Textiles, Technical University of Liberec
Example of measuring areas on organza,
Faculty of Textiles, Technical University of Liberec
Test results:
1.) The sample size measurement test showed strength stability in the case of uhelons and ulesters. With the normal tension that nets undergo as part of structural solutions in a hive, there is no need to worry about changes in the declared mesh size.
2.) * In the case of ordinary textile organza, there was a large dispersion in the measured samples from 309um to 326um. This is due to the thin structure of the fiber and the requirement for its use as a textile and not as a technical screen. Therefore, dimensions larger than those found cannot be excluded, e.g. when the organza is stretched more to one side.
The size of the female Melittobia Acasta found in the literature and my own microscopic observations showed a size of around 368 -340 um in the case of the head, 300 -316um in the case of the body and 380 -447um in the case of the bottom. There is a dispersion given by the size of the given individuals and their age. Given the size of the organza diagonal of 461um and its not completely constant length, the possibility of penetration cannot be 100% excluded when using organza. The Internet source also states the possibility of egg laying and the larval stage even outside the nest in the case of Aphomia Sociella with a larval body width of 300um.
In the presented table, the values are plotted in a color scale from bright green (most meets the required parameter) through yellow (limit values of the parameters) to dark red values (not suitable for breeding purposes in a given parameter) . Organza was taken as the reference value and samples of materials with meshes of the same size or larger were not included in the testing. With the exception of Ulester 32S and Ulester 31HDA, which have a rectangular profile, all other fibers are square. The prices of the materials are given as of July 10, 2018 and their amount may vary depending on the supplier. The prices were found only for some types of materials. In the case of organza, this is the current online offer, where there is /x next to the price, it is necessary to verify the minimum purchase quantity if interested. In the case of purchases over 25m, the manufacturer provides a quantity discount.
Conclusion and recommendations for choosing materials:
- For the construction of traps where the primary goal is not to ventilate the hive (corridor, flap trap), I recommend using the UHELON 53S material. Uhelon 53S still has good breathability of 65% compared to Organza, but its mesh size is 57% smaller. A mesh size in the diagonal of less than 200um should be a reliable barrier even against larval stages.
- For the construction of ventilation holes, I recommend using the Ulester 32S , the material stands out above the others with excellent breathability of 98%, the mesh size is already in the safe zone, the diagonal size is in the borderline zone, but it still creates a barrier. Due to the excellent breathability, two meshes can be used in ventilation traps, provided that they are not placed close to each other.
According to the manufacturer, unfortunately, Ulester 32S is not in regular production, only on order, where the minimum purchase quantity is 500m at a price of 214 CZK / m excluding VAT, which is above normal breeding possibilities. The material Uhelon 32S or Uhelon 35S or Uhelon 45S and Uhelon 53S . However, the choice must be adapted to the specific design of the hive with regard to the quality and method of ventilation. However, in these cases, I recommend using only one of these technical meshes in the ventilation system, which should be in a place where it can be cleaned of dust or water condensate, for example by gentle suction or air flow. - The mesh must always be protected from mechanical damage with another mesh that does not restrict breathability, but acts purely as mechanical protection.
- The screens must fit snugly against the edges of the opening design.
- Structural openings must be designed in such a way that it is possible to check the condition and integrity of the nets.
Technical data of the manufacturer: SILK & PROGRESS, spol. s ro task solver for Čmeláky Plus Kučera Karel
Examples of net applications on bumblebee hives:
Commercial product
ventilation insert made of inner cover mesh and barrier mesh made of Uhelon53S
Protective net under the roof of the hive.
Photo O. Hercog (2019)
using uhelon53S as a cover for the side odor trap on the flap
close-up view inside the trap
photo Kučera Karel
An example of a faulty mesh design.
The plastic protective inner mesh, which the bumblebees bite through, is in close contact with the inner barrier mesh.
example of subsequent modification:
loose (easy replacement possible) Uhelon 53S mesh and sealing insert together with protective aluminum mesh. The small hole serves as an entrance and internal trap for parasites (flies).
Final interior design in the hive. Free edges of the honeycomb behind paper lining, edge covered with a protective sleeve.
External view of the perfectly sealing Uhelon53S mesh in the ventilation hole.
An outer cover with a hole as a trap for parasites.
A parasite that seeks entry into the hive will crawl through the hole and remain in the interspace. This eliminates the risk of finding another way, such as through the hive's roof.
External final solution to the originally unsuitable ventilation.
Photo by Kučera Karel