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Monarch Butterfly Eggs (Facts, FAQ, Pictures)

Monarch butterflies are one of the most well-known insects in North America. Known for their beauty, these butterflies seem to melt the hearts of all they come in contact with. Sadly, monarchs are on the decline and it’s much rarer to see them now than it was 20-30 years ago. In this article, we’ll be discussing monarch butterfly eggs. We’ll touch on everything from how to attract butterflies to how many eggs they lay and everything in between.

Let’s have a look!

When do monarchs lay their eggs?

Monarch butterflies are fairly short-lived creatures. The first butterflies of the season generally start breeding in March, and then each generation will lay eggs roughly a month later.

Eggs take 3-5 days to hatch. Larvae/caterpillars take 9-14 days to reach their last instar/shed and form a chrysalis. It then takes approximately 8-13 days for the new butterfly to emerge from its chrysalis. After that, an additional 5-6 days for the female to be ready to breed. This means you could be spotting eggs in your garden every 25-38 days from March until September depending on where you are located.

Where do they lay their eggs?

monarch butterfly egg on a leaf
monarch butterfly egg | image source: USFWS Midwest Region via Flickr

Female Monarchs lay their eggs one at a time on the underside of the leaves of milkweed plants. Each egg is laid individually and glued on the plant with a special glue the mother produces specifically for the occasion.

monarch egg on a common milkweed plant leaf | by USFWS Midwest Region

How many eggs they lay vs how many survive

Each female monarch will lay an average of 300-500 eggs over a few-week period, but the record for most eggs laid was over 1000. While exact numbers aren’t known, it’s estimated that less than 10% of the monarch butterfly eggs that are laid each year will hatch and survive to adulthood.

Dangers to the eggs and caterpillars

Many other insects will often eat the eggs of monarch butterflies. Fire ants, mantids, lacewings, and paper moths are all egg eaters, and they aren’t the only ones.

Caterpillars face even more challenges with some species of flies and wasps laying eggs on their backs that hatch and bore into their skin. The parasites then feed on the inside of the caterpillar until it dies, at which time they emerge from the caterpillar and fall to the ground.

monarch butterfly caterpillar by Bernard Spragg. NZ via Flickr

Many species of bugs and birds also eat the caterpillars. While eating the milkweed plant does give the monarch caterpillars some defense against predation due to an enzyme produced by the plant, it’s clearly not enough to keep them completely safe.

If a caterpillar is able to successfully grow into a butterfly, its list of predators becomes much smaller and mostly consists of birds.

Loss of habitat and pesticide use are also huge threats to monarch populations all over North and South America.

Identifying monarch butterfly eggs

The eggs of monarch butterflies are very tiny, so it’s recommended to use a magnifying glass or jeweler’s loupe while searching for them. The eggs will be ridged and transparent and on the underside of milkweed leaves.

stages of monarch development by USFWS Midwest Region

The easiest way to find them is to keep an eye out for the adult butterflies and see where they are landing. If you notice them hanging out on the underside of your milkweed plants, it’s likely they are laying eggs.

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How to keep monarch eggs and caterpillars safe

If you’ve made your butterfly garden, but want to do more to keep your butterflies healthy and safe, you can always bring the eggs and caterpillars inside. The best way to do this is to set up a screened cage in a warm part of your house. Place newspaper or paper towels and a small glass of dechlorinated or spring water on the bottom. You can also buy one like this on Amazon for pretty cheap.

Once you find your eggs or caterpillars, cut a branch off the milkweed plant you found them on and place the bottom of it in the glass of water in your terrarium. The water will preserve the milkweed plant and keep it from drying out.

If your caterpillars are eating all of the milkweed you have provided, simply visit your garden to harvest more. It is very important when raising caterpillars that you keep their cages clean. Caterpillars do almost nothing but eat until they are ready to form their chrysalis. This means they will be making a lot of frass (feces) that will fall to the bottom of your cage. A dirty cage can lead to disease in your butterflies, so daily or every other day cleanings are very important.

Keeping the eggs and caterpillars inside until the butterflies emerge will keep them safe from the predators and parasites that wish to kill them.

Once your butterflies hatch and have had time to dry their wings, you can then gently move them outside to their new home, your butterfly garden. Here they will drink nectar, find mates, and make new eggs for you to tend.


How to attract butterflies to your garden

If you want to enjoy the miracle of the monarch butterfly lifecycle, the best way is to start your own butterfly garden. To do this you will need a small piece of land that is protected from the wind and gets plenty of light.

monarch butterfly

Plant lots of nectar-producing plants that blossom at different times of the year. This will make sure that all the generations of monarchs living in your garden will have food to eat all breeding season. Also, plant a species of milkweed that is native to your area.

Be sure when planting not to use any pesticides or herbicides as these can be deadly to your new butterfly friends. If you are buying adult plants in place of seeds, it’s important to be sure none of the plants have already been treated.


Conclusion

Monarch butterflies are a treasure and one we should do our best to protect. If you have the space and can add a butterfly garden to your yard, the butterflies will greatly appreciate it, but if you live in an apartment or an area where it just isn’t possible, having a nectar-producing plant on your window sill is a great help as well. You may not get to see caterpillars or eggs this way, but the hungry adult butterflies will thank you.

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