Tray Systems for Space-optimized Insect Farming Facilities

Insect farming includes the rearing of insects for substances that the insects produce, or for the insects themselves for use as feed or food source. Adult insects are bred to produce eggs, which hatch into larvae. Food and water are provided to the larvae to facilitate growth and development. After some time, larvae metamorphose into pupae and then into adults. Before the larvae transform into pupae, a large portion of the larvae can be collected and processed. Some are allowed to mature to reproduce - ensuring the self-sustainability of the insect colony. Larvae skin and frass are often collected to be used as a raw material to produce organic fertilizer, etc. 

Tenebrio molitor, commonly referred to as mealworm (in German "Mehlwurm"), for example, is best known for its larval form (see Figure). The mealworm itself is often used as living food for insectivorous pets, or as fishing bait. However, Tenebrio molitor is a prime natural source of proteins. The high concentration of proteins in Tenebrio molitor, its composition and a lipid profile that includes most of the essential fatty acids, make it a feed/food with interesting nutritional benefits and a low C footprint. There are a number of considerations for maximizing the efficiency of insect farming facilities. For instance, farming environmental conditions must be carefully taken into account: temperature, humidity, light, and ventilation. Pests must be contained.

Larvae and adult insects may be most efficiently housed within trays, stacked in space-optimized racks that are modular components in a larger facility. Given the manifold daily operations to be performed, it is key to maximize the (space and cost) efficiency of rearing systems - minimizing labour costs. We currently offer two compatible system for mealworm breeding:

• Mealworm tray and rack systems, allowing for easy maintenance of individual trays
• Stackable, stand-alone mealworm trays, providing a cost-effective solution for certain rearing stages and a save transport systems for living larvae

Tray & Rack Systems for Mealworm Production, space and labour efficient tray-based insect rearing systems for feed or food production, tested and optimised with mealworm farmers to meet the specific needs of your insect rearing facility. In particular, we manufacture cost-effective racks to hold standardized trays of your choice - building flexible, long-lasting and scalable rearing systems. We design racks to fit your facility, adjusting height, width and number of racks to make the most of your available space. We work with entomologists to advise on systems suitable for your target insects and the scale (scalability) of your insect farm. From previous projects, we have particular experience with rearing systems developed for mealworms.

Material Racks: Aluminium bars (5x5 cm; side poles) and angle aluminium bars (top and bottom, slides), stainless steel screws.

Various versions (see Types/Models below) to suit all tray sizes and the spatial configuration/workflow of the facility:

• Loads trays from one or two sides (front and back, standard)
• Side-by-side units with two or three adjacent racks in one unit (with shared centre poles)
• Fixed legs (standard), or on turnable wheels
• Optional: with mesh sides, bottom, top, & mesh front door (for potential isolation of infested trays); higher or lower racks; orientation of trays, ...

Trays: Standard, commercial trays depending on species (PP, grey; various dimensions).

The production trays used are standardized ("Euroboxes") and are purchased in bulk directly from the manufacturer to provide the most cost-effective tray and rack systems for insect production and to allow for easy facility expansion without changing the rearing tray type. Contact us to discuss your insect rearing objectives and how VSI's mealworm racks can support your goals! 

Insect Production Racks are shipped pre-assembled. The side/middle panels with slides are assembled, while the top and bottom bars can be easily installed by the customer - resulting in significantly reduced shipping costs. All parts are included for easy do-it-yourself installation. We are happy to get you started with the installation via video call; fully assembled or on-site installation service available upon request.

Stackable rearing trays. The stackable trays are suitable for a variety of insects including mealworms and are ideal for use with automated systems, providing sufficient height and an open corner design to optimise ventilation, particularly during transport. Available tray sizes are 60 x 40 cm (W x L) with a height of 14.5 cm or 19 cm (H) and 80 x 60 x 19 cm (W x L x H). This stackable insect rearing tray design does not allow individual trays to be removed (unlike the production racks above), this has minor disadvantages at rearing stages where development between trays is not 100% homogeneous, potentially requiring different feet to be applied to different trays and/or hindering the collection of early emerging beetles to prevent cannibalism. However, at certain stages and during transport of live larvae to customers, the stackable trays are a viable solution to both reduce the cost of (rack) infrastructure and/or to prevent excessive temperatures developing in closely stacked Euro trays (as above). Based on our customers' experience, we therefore recommend that the cost-effective stackable trays are used in addition to tray and rack systems in a mixed operation.

Mealworm rearing rooms are ideally maintained at a temperature of 25-30°C and a relative humidity (RH) of 50-75% (Manojlovie, 1988; Chen and Liu, 1992). Plastic trays are commonly used in European and North American farms.

The optimum density for rearing adults is approximately 0.94 larvae per cm2 (i.e. ~2200 larvae per 60 x 40 cm tray). Adults typically begin oviposition on the fourth day after emergence. Oviposition substrates, such as a wheat bran bedding contained within a mesh screen, are used to collect semi-synchronized eggs. During the 40-50 day spawning period, adults must be transferred to another container every 3–5 days to maintain semi-synchronized eggs. Larvae typically hatch approximately 7 days after egg deposition. For commercial larval production, the recommended rearing density is 1.18 larvae per square centimetre (Wu, 2009), i.e. ~2500 per 60 x 40 cm tray. 

The medium used to raise mealworms, both larvae and adults, is a mixture of wheat bran and partially vegetables. For optimal mealworm nutrition, the water content of the wheat bran and vegetable feed should ideally be ~18% (Wu et al., 2009). Vegetables should be washed and air dried to remove potential pesticide residues, soil, etc. On a daily basis, one hundred larvae require approximately 6-10 g of wheat bran and 0.6-1.0 g of fresh vegetables (such as carrot, cabbage, pumpkin, etc.), which should be added separately at regular intervals (twice a day) and removed immediately if spoiled.

Larval segregation and collection is primarily accomplished by the use of a 60 mesh screen, a process that has been partially automated in some facilities by the use of an electric vibrating screen (see image). Some degree of automation for larval collection and frass removal is key for the efficient operation of a medium (perhaps starting with a few hundred trays) to larger scale insect farm. Full automation of feed application, tray placement and removal, and sorting are hot topics for successfully scaling mealworm farms to mass production facilities.