What Do Monarch Eggs Look Like?

Monarch butterfly eggs are small, round, and white or off-white. They have ridges on the sides and are found on the underside of milkweed leaves. The egg will darken slightly in color before it hatches.

Description of Monarch Butterfly Eggs

Monarch butterfly egg
Monarch butterfly egg

Monarch butterfly eggs are small and white or off-white in color. They are usually ovoid in shape and about 0.04 inches (1 mm) in size. Monarch butterfly eggs have vertical ridges on the surface, but usually, the ridges can only be seen with a magnifying glass.

These eggs darken in color when they are close to hatching. If the egg turns black, that means the caterpillar did not survive.

Butterfly eggs are surrounded by outer shells to protect the developing larva. The shell has a layer of wax covering it to prevent the egg from drying out. At the top of the egg is a micropyle, which is a small funnel in which the sperm enters the egg. This narrow canal also allows water and air to enter to assist with egg development.

Where Do Eggs fit within Butterfly Life Cycle?

The egg is the first stage in a Monarch butterfly’s life cycle. Butterflies go through a process called metamorphosis. Metamorphosis consists of 4 stages:

  • Egg
  • Larva
  • Pupa
  • Adult

The egg holds the baby caterpillar. Monarch caterpillars tend to hatch after about 3-8 days after being laid. They then enter the larva stage, which is also known as the caterpillar stage.

The Monarch butterfly caterpillar spends the majority of its time eating and growing by molting. The first thing a caterpillar eats is its eggshell.

During its fifth instar, the caterpillar will begin the pupa stage. The pupa stage is when a butterfly is encased in a chrysalis and begins metamorphosis.

Monarchs spend about 8 to 15 days in the pupa stage. Once it emerges from the chrysalis, it enters the last stage, which is the adult stage. The main goal of an adult butterfly is reproduction.

Both genders of butterflies will immediately search for a mate to continue the life cycle.

Where Do Monarch Butterflies Lay Their Eggs?

Monarch butterflies lay their eggs on the underside of the leaf to protect the egg from poor weather and predators. When female butterflies lay their eggs, they secrete a small amount of glue-like substance to attach the eggs to the plant. The glue is very strong and fast drying. The egg cannot be separated from the glue without destroying the egg itself.

What Plants do Monarch Butterflies Lay Their Eggs?

Monarch on a milkweed
Monarch on a milkweed

Adult Monarchs lay their eggs on milkweed plants since their caterpillars eat milkweed. Their eggs could be found on milkweed leaves, stems, or stalks.

When the Monarch caterpillar is born, it immediately eats the milkweed plant. Monarch caterpillars only eat milkweed plants. They cannot survive without it.

Milkweed plants contain cardenolides, which are toxic steroids. The Monarchs store cardenolides to emerge as adults still holding the steroids in their bodies.

Predators dislike the taste of these steroids, so eating milkweed plants also keeps them safe from predators. When a bird attempts to eat a Monarch caterpillar or adult butterfly, it often regurgitates.

Monarch butterflies will only choose milkweed plants as their host plants. There are 9 milkweed species, and while female Monarchs will lay eggs on all 9 , they do prefer some over others. Swamp milkweed, balloon milkweed, and common milkweed are the types of milkweed plants that Monarchs prefer to lay eggs on.

How Many Eggs do Monarch Butterflies Lay?

Female butterflies lay 300-500 eggs over two to five weeks. They lay one egg at a time, but they can lay a high number of eggs in a day. This butterfly will lay an egg and then retract for a few moments before laying another one.

The eggs can be on the same plant and on the same leaf, but they will be distanced apart. One leaf may hold 2-3 Monarch eggs, but the mother spreads them out, so the caterpillars have enough milkweed to eat when the eggs hatch.

Monarch Butterfly Eggs vs. Aphids

The main difference between Monarch butterfly eggs and aphids is their color. Monarch butterfly eggs and aphids could be confused with one another since they are both found on milkweed plants. However, aphids are bright yellow in color, while Monarch butterfly eggs are white or off-white.

Another way to tell the difference between the two is by the amount. Aphids remain in clusters with each other. This information helps you identify which is which since Monarch butterflies lay a single egg.

Aphids have six black legs. The larva inside Monarch eggs does not move, so if you see movement, you are most likely looking at an aphid.

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