Understanding the lifecycle of a mealworm is essential to manage a colony. As outlined below the lifecycle consists of 4 life stages consisting of Beetle (Adult), Eggs, Worm (larva) and Pupa.

Below is a summary of the life cycle of a mealworm and the things to consider to have a productive mealworm farm.

mealworm

Photo of the Mealworm Lifecycle (photo by uen.org)

Eggs

  • Eggs are laid to any surface which may be substrate, container bottom or egg cartons. Check for eggs by looking at small white dots about 2mm in diameter on the bottom of the container.
  • They hatch typically around a week later although it will take much longer for non optimal conditions (up to 4-8 weeks for low temperatues).
  • It may take a few weeks before the baby mealworms are large enough to see with the naked eye. Most will hang around the wet food.
photo of yellow mealworm eggs on the bottom of a blue mealworm tray. Eggs look like numerous yellow dots

Larva (Worms)

Instars (Moults): Worms go through approximately 15-23 instars or molts before finally developing into a pupa. After Each molt they are susceptible to dehydration if wet food in insufficient or there is low humidity and high temperatures.

Food: In the wild mealworms eat foods such as leaves, compost, droppings and even dead animals.  In captivity they eat most grains, meal and flour products. Refer to Food sections for more details.

photo of a group of yellow mealworms close up on a white background

Pupa

Worm to Pupa Development Time: Has a bell shape curve with some developing early, the bulk developing in the middle and some developing late. Depending on conditions it can take 3-6 months for worms to go to pupa.

Pupa to Beetle Development Time: Varies with conditions however is around 5-20 days. With optimal climate conditions it will take less time and with less optimal conditions it will take longer. For instance we noticed pupa which had been sitting for weeks in hot 35 celcius degrees (95 Fahrenheit) with no climate control in summer, went to pupa overnight when we commenced air conditioner set to 25-28 degrees (77-82 Fahrenheit).

Factors that Slow Down Pupa Development include: high worm densities, high or low temperatures and humidity (see following sections), insufficient wet and dry food (substrate) and infrequent removal of frass.

Factors that Increase Pupa Development include: low worm densities, optimal temperature and humidity levels (see following sections), regular removal of frass.

Causes of Death: Pupa are the most vulnerable life stage and have high death rates if not managed properly.Normal death rates on the lower end are around 10% and up to 25% at the higher end. 

close up photo of a pile of mealworm pupa on wheat bran

Beetles (Adults)

Life Expectancy: Beetles have an average life expectancy of approximately 3-6 months depending on temperature. Productive breeding occurs in the first 4-6 weeks.  All life stages has a bell shape curve, with some dying earlier, the most dying in the middle and some taking longer.

photo of mealworm pupa and beetles in a blue mealworm tray. Beetles have climbed onto square egg carton