What is Egg Loading?
You’ve heard the statement, “Three’s a crowd!” Well, in the monarch world the same holds true. Laying eggs on healthy, lush milkweed plants is extraordinarily important. Emerging monarch caterpillars chew, munch and devour their own eggshell for nourishment, but they may also ingest the eggshell of another if close by.
For this reason the female seeks to lay her eggs very carefully – only one egg per plant. Notice the differences between the egg photos on this page! They tell a story.
When milkweed is scarce and a shortage affects the habitat, seeking out viable plants becomes difficult. The female reverts to laying more than one egg on the same leaf or plant. Also, if she is very tired near the end of her laying period, she may place three or more on the same leaf. “Egg loading” can occur when milkweed is not plentiful. Planting milkweed and nectar producing flowers to replenish deficiencies in the habitat is crucial to the future of the monarch butterfly… and the bees!
PHOTO: Holli Webb Hearn
Pretend you are a tiny little caterpillar! You are growing inside the tiny little white egg your monarch mother laid a few days ago on a delicious milkweed leaf. Your beautiful egg is not round, but oval in shape . . . like a football. Tiny lines can be seen on it from top to bottom. Eggs that are in the shape of circle are another type of insect.
Children playing in fields will be able to find you. If they look closely, they may even be able to see your tiny black head at the top of your eggshell. After three or four days, when the time is exactly right, you begin to chew a hole in the top of your eggshell. Your body has begun to grow and you are feeling very squeezed and cramped! There isn’t very much room left inside that eggshell. How exciting it is when you chew through the top of the shell.
Now you can peek out and see balloons of pink milkweed buds swaying in the warm summer breeze. If you look closely, you can see other eggs that another mother monarch has laid. She will lay hundreds of eggs in a day.
OK…now let’s get back to work. Keep chewing and when the opening is big enough, you can crawl out…push…tug…wiggle…squirm…squeeeeeeeeze your way out! WOW!
PHOTO: Edith Smith 2005
“Why should I do that,” you ask?
To protect hatching Monarch caterpillars and adult butterflies!
A hatching Monarch caterpillar eats its way out of its eggshell. If there are pathogens left by the adult butterfly as she laid the egg, the caterpillar eats the pathogens and becomes ill.
The Monarch Program website gives information about two common types of pathogens that attack Monarch Butterflies: Baculoviridae (nucleopolyhedroviruse) and Neogregarin (Ophryocystis elektroscirrha).
Baculoviruses are pathogens, like some human viruses, which attack insects and arthropods, while Neogregarin (Ophryocystis elektroscirrha) is a tissue specific parasite from the family Neogregarinidae. Neogregarin does not kill caterpillars, but adult Monarchs that are heavily infected often die before they mate, don’t live long, and are smaller than normal.
This video illustrates how to disinfect eggs – or if you prefer, use the following directions.
Eggs can be disinfected on or off the leaves. If you prefer to take them off, allow several hours for the eggs to dry. If the leaves have been picked from the plant, it is more difficult to take the eggs off the leaves. As leaves begin to wilt, they become elastic. As you gently rub the egg, the leaf moves instead of the egg. To prevent this, I wrap a wilting leaf around my finger, holding it taunt, and remove the egg with my other hand. This video illustrates how to remove eggs from a fresh leaf.
Disinfect Monarch Butterfly Eggs on Milkweed Leaves. Some eggs will come off the leaves.
If eggs are left on the leaves, be aware that some eggs will come off as they are disinfected. A strainer will be used in the process. The strainer MUST have a very fine mesh, whether it is a kitchen strainer or a piece of cloth/tulle/screen.
The instructions for disinfecting eggs are the same whether the eggs are on or off the leaves.
It is simple and easy to disinfect eggs. If you are nervous, we recommend practicing with dry grits, rice, or other item until you are comfortable with this process.
If this makes you nervous, simply practice on dry grits, rice, or other tiny objects until you are comfortable with the process.
*Water/bleach ratio is 19-1. This means 19 tablespoons water and 1 tablespoon bleach. It means 380ml water and 20ml bleach. Whatever measuring unit you use, mix 19 parts water and add 1 part bleach. This recipe is based on a bleach that is 6.5% – 8.25% sodium hypochlorite percentage. Do not use stronger bleach with this recipe. See photo below to know what to look for on the label. This bottle of bleach has an 8.25% sodium hypochlorite percentage. This means that for every 19 tablespoons of water, 1 tablespoon of this bleach would be added to make the disinfecting solution.
**Pouring eggs into the solution takes time because many of the eggs or bits of leaves will stick to the container. You’ll need to move those that stick to the solution and that normally takes five to 20 seconds. At that point, you choose to either leave the original ones in longer than 60 seconds or allow the late ones to be removed early. In too long, the eggs will liquefy. In too short, pathogens won’t be killed.)
***At 60 seconds, remove the eggs IMMEDIATELY from the bleach and place them in plain water. They aren’t as fragile as you think. Moving fast is much safer than allowing eggs to remain in disinfectant longer than 60 seconds. If you move slow and careful, some eggs may be in the solution too long and become damaged. If you watch the video, you can see how this is easily done quickly, without harming any of the eggs.
PHOTO: Holli Webb Hearn
It’s been an exciting morning, but now it’s time to do what YOU do best…monarch caterpillars are munching machines! They eat all day long! They munch, crunch, munch milkweed. Just look around…milkweed is growing everywhere! What an exciting view…off in the distance another little monarch caterpillar is busy munching milkweed, too. Now it’s YOUR turn to proudly start your day and say
“Hello world”…”I’m a monarch caterpillar!