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Author: Dr. Adrian Lawler  
Title:  Raising mealworms for animal food
Summary: Yellow mealworm larvae or adults serve as food for fish, reptiles, birds and other animals. They are relatively easy to raise, as detailed here. Includes a unique list of "problems" learned from long experience.

Contact for editing purposes:
email: Adrian Lawler <>

Date first published: February 2004
Publication:  Aquarticles (Not previously published).
Reprinted from Aquarticles:
November 2004: Posted on
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Dr. Adrian Lawler,
P.O. Box 48,
Ocean Springs.
MS 39566
#205 - 5525 West Boulevard
Vancouver, British Columbia
V6M 3W6

Raising mealworms for animal food

by Dr. Adrian Lawler
(retired) Aquarium Supervisor (l984-l998) J.L. Scott Aquarium Biloxi, MS 39530

Yellow mealworm (Tenebrio molitor L.) larvae are sometimes called "golden grubs" and make good fish bait; larvae and adults serve as food for animals (birds, frogs, turtles, lizards, fish, etc) in aquariums and zoological parks, and are relatively easy to raise. They can supplement the diet of various animals, or be a major part of the food of some toads, frogs, lizards, etc. held in captivity.

Length of the life cycle is 3-5 months, depending on various factors as food, temperature, moisture, etc. The larval stage may include 9-20 molts. The beetles and larvae eat decaying leaves and plant matter (occasionally new plant growth), dead insects, feces, cornmeal, flour, cake mixes, cereals, meat scraps, bran, stored grains, etc., and litter found in chicken houses, bird nests, and animal nests.

Here I present a brief summary of one way to raise mealworms:

1….Construct two rearing boxes with the following characteristics (I prefer wooden boxes, but ventilated plastic boxes could be used):
    A….4-6 inches deep…..length and width can be varied to suit your rearing space, and the size of your production operation. I used boxes that were about 6" by 14" by 24" and they provided enough larvae and adults to feed many animals in a public aquarium 1-3 times per week.
You need either 2 boxes or 2 sections in one box in order to have a place to put the food and debris (with included eggs and larvae) from one box when you clean it so that eggs and larvae are not lost and your production set back.
    B….Attach legs of length you want to corners of box (about 24").
    C….Place each leg into a small container containing water as a deterrent to keep ants from climbing up legs and getting into your culture.
    D….Attach a screened (for ventilation, and to keep roaches and moths out and mealworms in), hinged lid at top of box, getting a tight fit of lid to keep roaches out of your culture, and mealworms in.
    E.....Place culture box inside, in an area of subdued light, away from a wall or other thing that ants might crawl up in order to enter box.

2….Obtain a culture of mealworms from a pet store, a biological supply house, an aquarium, or a zoo. If possible, get a mixed culture, containing all life stages from egg to adult, so that you can quickly get larvae to feed out.

3….Put a 1-2" layer of chicken laying crumbles in the bottom of your culture box as a food source for the mealworms. Add a water source for mealworms; source can be a cut vegetable or fruit (apple, pear, orange, potato, banana, etc), or a sponge, rag, etc. in a shallow dish (so laying crumbles do not get too moist and then moldy). Although other food sources can be used, I found laying crumbles to be the best and easiest food to use.

4….Periodically check culture to see how mealworms are doing, to verify moisture is still available, to add water to dishes at legs, to remove roaches, and to check for ants.

5….After the culture becomes established enough for the numbers you want to feed out, then you can start harvesting larvae (and adult beetles).

6….Just before the mealworms have turned the laying crumbles in fine debris and excrement, add another 1" layer of laying crumbles for new food. Or you can add a cup or two of crumbles weekly.

7….When the culture box gets fairly full you will need to remove part of the debris, which also contains eggs and larvae, to the second box so you do not lose eggs and larvae, and add laying crumbles to the space left by debris removal and to the second box. After the second box gets well established, and then full of debris, you will periodically need to discard some of the debris so boxes do not get too full. You can save some of the larvae in the debris by putting the debris through a screen of suitable mesh size, or putting the debris in a funnel with a light bulb above it. Larvae will try to avoid the excessive heat of the bulb, will migrate down the debris, and drop out of the funnel into a container placed under the funnel.


---Keep legs of box in water containers to keep ants out of culture.
---Keep box lid tight to keep roaches and moths out of culture.
---Take boxes outside when you harvest mealworms IF you also have moths in the culture. You do not want to let moths loose in your house, where they will attack various pet and human foods, or clothes.
---Mites that may appear, which eat debris, etc., do not seem to harm the culture.
---Fruit flies can get established in the box if you use fruit or vegetable for moisture, or the crumbles get too wet. These larvae or flies can be used as another food for your animals, or can be discarded.
---Keep extra chicken laying crumbles in a fridge or freezer to avoid ant infestation and moldy food.
---Make sure you do not harvest too many adults and thus decrease egg production.
---Over time, as debris increases, the waste products will emit an ammonia-like smell, and part of the debris will need to be discarded.
---Boxes that get too full present short vertical distances for mealworms to crawl up to lid, and make it more likely for them to escape through cracks around lid.