Why are my Darkling Mealworm Beetles different colors? I purchased mealworm beetles but when they arrived they weren't all black like the photo, are they sick or old?
The quick answer is "No they are not sick or dying, they are young and will darken to black soon."
The longer explanation is when the beetles emerge from the pupa stage they are a light cream color, but they are soft and need to allow their wings to harden. As the beetles' wings dry and harden they gradually get darker, eventually turning black. We pack up the beetles only once they turn into the medium to dark rust color you see in the above photo. This ensures that their wings have had enough time to harden so they are not damaged during shipping. Your beetles will still be young enough that they are just starting to breed and lay eggs. While the tenebrio molitor beetles can produce many eggs, they lay most of their eggs in the first half of their 2-4 months of life as a darkling beetle. We want them to produce the most they can for you so your beetles will be between seven and ten days old when they arrive. Since the beetles' wings dry at different rates depending on a lot of factors, you may see beetles at different stages of drying or they may be completely black by the time they arrive.
Once the darkling beetles turn black you will notice breeding and may even witness some egg-laying, depending on how you have set them up. When your beetles arrive you'll want to get them into your desired setup, cut carrots into rounds, and place them in with the beetles as they will be ready to eat by the time they reach you.
Laying eggs take a lot of moisture out of your beetles, make sure to feed them moist foods every other day. When feeding you want to give enough moist food so they will eat all within 24 hours. Too much moisture on your wheat bran can cause mold or even cause a grain mite infestation.
How many eggs should I expect my beetles to lay each week?
To get an idea of what your farm can produce with the number of beetles you have, multiply the number of beetles by 6.6, this will give you the number of eggs per week, that your farm has the potential to produce. There are many factors to consider when trying to calculate how many eggs your farm can produce each week. If we assume that your beetles are 50% males and 50% females, they are reproducing at the same rate throughout their lifetime, and your farm is running at the optimal temps, humidity, and feeding schedule, then it would be easy to answer. However, we already know that tenebrio molitor beetles lay most of their eggs in the first half of their lives, and other factors may reduce how many they lay over their individual lifetimes. So if you have 500 beetles, your farm will produce approximately 3,300 eggs per week, this number will be higher during the first half of their and lower during the second half and may also be different based on other factors. Replace your beetles every 2 months for optimal egg production for your worm farm.