As outlined in the Essential Tips for Mealworm Breeding Consistently section, the main factors that impact on productivity is climate, pupae and Beetle densities/survival rates, demographics and user skill/methods.

Growing  Conditions

The production rates outlined below are based on the following:

• Climatically controlled 6m (20 foot) caravan using air conditioning, humidifier (no dehumidifier) and ventilation fans. Closed system with minimal gaps for pest entry.
• Temperature set to 25-28 degrees (77-82 Fahrenheit) and humidity to 50-60% relative humidity (RH).
• Blended diet of wheat bran, wheat mill run, chicken starter crumble, as outlined in Mealworm Substrate Section.
• Using the Filtering method as described in Filtering Method Overview (Yellow Mealworms) section.
• This equates to  100 tray in a 2.4m wide by 3m long by 2m high space (7.8 by 9.8 by 6.6 feet)

Worm Growth 

Yellow mealworms took approximately 12 weeks (2.5-3 months), to reach large size suitable for sale.  It takes approximately 2 weeks to go from medium to large size. Non optimal conditions will take longer.

Below are estimated size of worms based on weeks:

8 Weeks (2 months)-             1.0-1.5cm-small

9 Weeks (2.25 Months)-        1.5-2cm (Small)

10 Weeks (2.5 Months)-        1.5- 2cm (Small)

11 Weeks (2.75 Months)-      2.3cm (Mediums)

12 Weeks (3 Months)-           2.5-3cm (Large)

13 Weeks (3.25 Months)-     2.5-3cm (Large- some just starting to go to pupae)

18 Weeks (4.5 Months)-        Worms placed in high density to suppress pupation, still salable.

Production Rates/Per Tray and Beetle Density

Below are some “rules of thumbs” to estimate production rates based on beetle densities. In this way you can customize your farm to suite the density strategy you prefer (ie medium densities to increase growth, and reduce pests;  or higher densities, higher output, higher risk of pests).

The below figures assumes; one tray of beetles at a given density (see below), would produce approximately “X” amount of worms (in grams or kilograms) after 12 weeks. Weights will increase over time (see below section).

• 250ml (8.8 oz) of Beetles per tray (low density), will generate enough eggs when filtered weekly to produce approximately 330-400 g (11.6-14.1 ounces)
• 500 ml (17.6 oz) of Beetles per tray (medium density), will generate enough eggs when filtered weekly to produce approximately 660-800g (23.3-28.2 oz)
• 750 ml (26.4 oz) of Beetles per tray (high density), will generate enough eggs when filtered weekly to produce approximately 1-1.2kg (2.2-2.6 lbs)
• 1L (35.2 oz) of Beetles per tray (very high density), will generate enough eggs when filtered weekly to produce approximately 1.3-1.6kg (2.9-2.5 lbs)

Increased Weight with Age

Amounts outlined above are at week 12. As worms get older the overall weight will increase. For instance if the worms at week 12 weighs an average of 1.2kg it may weigh another 250g in 1-2 weeks.   Once the trays get over 1.5kg the increase in weight/week will slow down as food resources, crowding and stress will reduce growth. 

This is an important point as if you have a big demand in worms and you sell them earlier (for example week 10 or 11),  the volumes you get over all will be much less.  If you have a slow period in sales the volume per tray will increase due to the longer time they spend in the trays.

Total Production Rates 

In the filtering method example (see Filtering Method Overview- Yellow Mealworms) we have the following:

• 85 rearing trays
• 7 beetle trays at high density (750ml of beetle)

If there are 7 beetle trays, each rearing 1-1.2kg (2.2-2.6 lbs) after 12 weeks, you will generate approximately 7kg-8.4 kg (2.2- 2.6 lb) per week (multiply weight/tray by 7).  Its no accident that if you multiply 7 beetle trays by 12 you get 85 rearing trays. 

Feed Consumption

• Mealworms consume slightly less than  their body weight per day in ideal conditions as described above.
• Trays with beetle, egg and small worms consume very little meal which do not need significant replacement for around 3 weeks or more. Assume around 2kg/week for all these trays. You will place more than 2kg of feed in the trays, but this will be consumed once the mealworms get larger.
• Medium Mealworms– Trays with medium sized mealworms are growing rapidly but their weight is around 400-700 grams/tray. This equates to 30kg of feed for 14 trays of mediums (over two weeks).
• Large Mealworms- Based on the above figures of around 1.2kg of large mealworms per tray, they will consume around 1kg of food per day. This means that the largest worms before harvest with 7 trays as described above, will consume around 50kg of feed per week. This is their peak consumption. At this age they increase in body weight very quickly (could get to 1.8kg if you keep them for longer periods than 12 weeks) but the food consumption becomes uneconomical. You should aim to sell or freeze your large mealworms to prevent excessive food expenses. Replacement of meal at this time should be every few days for top ups.
• Total Consumption: In total for large, medium and small/beetle trays this equates to around 80kg/week. We buy our meal in 20kg bags so we consume around 4 bags per week for the amount of trays described in our standard set up for a 3m by 3m space. In reality this can change from week to week and could be as low as 2-3 bags depending on sales and demographics of the colony. For instance we may get a large order for small to medium mealworms which then don’t get to large size and reduce feed over the next 3-4 weeks.
• The above figures will also  change depending on density of beetles you use  (ie 500g or 750g), your set up and the demographics of your colony (do you have a lot of young trays or older trays past the 12 week period in off peak seasons like winter). Every farm will have different factors and you will need to work out your own facility specific feed rates.