Conserving threatened organisms requires knowledge of the factors impacting their populations. The Eastern monarch butterfly (Danaus plexippus L.) has declined by as much as 80% in the past two decades and conservation biologists are actively seeking to understand and reverse this decline. While it is well known that most monarchs die as eggs and young larvae, few studies have focused on identifying what arthropod taxa contribute to these losses. The aim of our study was to identify previously undocumented predators of immature monarchs in their summer breeding range in the United States. Using no-choice feeding assays augmented with field observations, we evaluated 75 arthropod taxa commonly found on the primary host plant for their propensity to consume immature monarchs. Here we report 36 previously unreported monarch predators, including representatives from 4 new orders (Orthoptera, Dermaptera, Lepidoptera and Opiliones) and 11 taxa (Acrididae, Gryllidae, Tettigoniidae, Forficulidae, Anthocoridae, Geocoridae, Lygaeidae, Miridae, Nabidae, Erebidae and Opilliones). Surprisingly, several putative herbivores were found to readily consume immature monarchs, both in a targeted fashion or incidentally as a result of herbivory. This work expands our understanding of the monarch predator community and highlights the importance of unrecognized predation on insects of conservation concern.
Butterfly eggs are a fascinating part of the insect’s life cycle. These delicate eggs undergo an incredible transformation into caterpillars and eventually adult butterflies. Learning to identify different types of butterfly eggs can open up a world of wonder. This guide will provide a comprehensive look at butterfly eggs, including how to spot them, what they look like, and how they hatch into caterpillars.
What Do Butterfly Eggs Look Like?
Butterfly eggs come in a variety of shapes, sizes, and colors. However, many share some common characteristics:
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Size – Butterfly eggs are very small, usually 0.5 mm to 2 mm long. Some species lay eggs almost too tiny to see!
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Shape – Spherical and ovoid (egg-shaped) are the most common shapes among butterfly eggs. Others may have a more cylindrical tubular, or flattened look.
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Color – Many eggs are green, yellow, or white. Some species lay eggs that are red, pink, orange, metallic, or nearly black. Often the eggs will change color as they mature.
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Surface – The egg surface may look smooth glossy matte, or translucent. Some have ridges or bumps. Tiny spikes or hairs on the eggs help anchor them to leaves.
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Markings – Tiny dots, streaks, and stripes adorn the eggs of certain species. These markings camouflage the eggs or may warn predators of distasteful chemicals
Where Are Butterfly Eggs Found?
To find butterfly eggs, look carefully on or near the caterpillar’s host plant. Most species lay eggs on the leaves, stems, buds, or flowers of the plant the caterpillars will eat. Some butterflies drop eggs on the ground near the host plant. Good places to search include:
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Undersides of leaves – Butterflies often lay eggs on the underside of leaves to help hide them from predators. Carefully turn leaves over to spot eggs.
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Leaf veins and stems – Butterfly eggs may be laid on or near the central leaf vein. Also check stems and tendrils.
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Leaf axils – Check the joint where the leaf stalk meets the stem. Eggs are sometimes laid in this protected spot.
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Flower buds and fruits – A few species lay their eggs directly on flower buds or green fruits of the host plant.
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Near the ground – Some eggs may be found on low plants or dropped to the soil, especially in the cabbage butterfly family.
When Are Butterfly Eggs Laid?
Butterfly egg laying is closely tied to the adult flight period. Depending on the species and location, butterflies may lay eggs during spring, summer, or fall. Tropical species may reproduce year-round. Peak egg laying usually coincides with the flight period of that butterfly in your region.
For many butterflies, peak flight occurs 1-2 times per year. For example, monarchs generally have two breeding cycles, one in early summer and another in late summer/fall. In warmer climates, some species may have multiple broods that allow almost continuous reproduction.
Observing butterflies in your area will help pinpoint when females are most actively searching for host plants to lay their eggs. This is the best time to start searching for eggs!
How Many Eggs Do Butterflies Lay?
The number of eggs a single butterfly will lay varies widely, from just a few to several hundred. Some factors that influence total eggs per female include:
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Butterfly family – Some families, like the brush-footed butterflies, lay hundreds of eggs. Gossamer-winged butterflies lay just a few eggs.
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Host plant – When the host plant is abundant, a female can lay more eggs than when it is scarce.
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Predators – High predation causes some butterflies to lay more eggs to compensate.
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Weather – Warm, favorable conditions allow for more eggs compared to cool or drought conditions.
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Age – Older, more experienced females often lay more eggs than newly emerged females.
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Mating frequency – Multiply mated females lay more eggs than those who mate just once.
Here are some examples of egg numbers for common North American butterflies:
- Monarch – 300 to 500 eggs
- Painted lady – 500 to 1000 eggs
- Swallowtails – 30 to 250 eggs
- Whites and sulphurs – 20 to 100 eggs
What Are Some Common Butterfly Egg Host Plants?
Butterflies rely on certain “host” plants to feed their caterpillars. Some widespread butterfly host plants include:
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Milkweed – Monarchs and queen butterflies lay eggs on various milkweed species.
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Nettles – Red admiral, painted lady, and comma butterflies use nettles.
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Parsley and dill – Black swallowtails lay eggs on these and other herbs.
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Crucifers – Cabbage white butterflies use cabbage, mustard, and nasturtiums.
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Legumes – Sulfurs and hairstreaks lay eggs on peas, beans, and clover.
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Citrus – Giant swallowtails prefer citrus trees.
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Willows – Viceroys, mourning cloaks, and swallowtails lay eggs on willow leaves.
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Oak trees – Hairstreaks and duskywings use oaks.
Getting to know your local butterfly host plants is a key step to finding more species of eggs in your area!
How Do the Eggs Hatch?
After 5 to 10 days, tiny caterpillars chew their way out of the eggs. Temperature and humidity impact the speed of hatching. Warmer, more humid conditions may speed up development. Cooler temperatures slow the embryo growth down.
Just before hatching, the egg color often changes as the caterpillar develops eyespots and a chewing mouthpart called a mandible. Right before emerging, the ‘head’ end of the caterpillar partially splits the eggshell. The caterpillar will wiggle out of the rest of the opened shell.
Spotting Butterfly Eggs in Your Garden
Butterfly eggs are small and well-camouflaged, but with careful observation, you can find them! Here are some tips:
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Learn the host plants of species in your area and regularly check them.
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Search on the undersides of leaves, especially new leaves and buds.
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Use a magnifying glass to scan for tiny eggs on foliage and stems.
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Look during the peak flight period when egg-laying is at its highest.
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Check plants in secluded areas away from heavy predation.
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Mark plants where you find eggs to easily monitor them.
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Enhance your garden with nectar plants to attract more egg-laying females.
The miraculous metamorphosis from a miniature egg to a colorful winged butterfly is a wonder of nature. Learning to identify butterfly eggs opens up amazing opportunities to observe this incredible transformation right in your own backyard!
Egg and neonate trials with ants
Because individual ants do not forage normally when displaced from the colony, ant predation was assessed by linking a predation arena (described above) to an ant colony held in the lab. Colonies of six different ant species and associated soil/litter were collected from locations in and around East Lansing, Michigan and placed in 20 × 21.5 × 11 cm (4 L) containers with Fluon (#2871C Insect-a-slip) applied to the inner top 2.5 cm to keep ants from escaping. Colonies were provided food and sugar water 2x per week and starved for 24 h prior to use in feeding trials to encourage foraging. As described above, monarch eggs or neonates were placed individually on field-collected A. syriaca or A. incarnata leaves in 473 mL deli-cups. We then connected ant colonies to the deli-cups using clear, flexible PVC tubing (0.64 cm ID, Model 702165 Home Depot; Fig. 1). We applied Fluon to the inner top 2.5 cm of each deli-cup to keep ants from escaping through the perforated lid. To initiate a trial, a wood coffee stirrer (3 mm width) was placed to connect the soil surface in the ant colony to the tube, allowing ants access to the test arena. The colony and arena assembly were then placed in the growth chamber and the egg/neonate presence was recorded at 48 h.
Collection and identification of potential predators
We limited the range of arthropods we tested to those observed or collected on common milkweed, since they are most likely to encounter immature monarchs in a field setting. We excluded potential aerial predators not found foraging on milkweed stems, as well as parasitoids36,57. Arthropods used in the experiment were field collected from A. syriaca patches using sweep nets, aspirators, or hand collection in Ingham County, Michigan, USA and State College, Pennsylvania, USA during the summers of 2017 and 2018 and used in trials within 24 h of field collection. Once trials were completed, arthropods were frozen, placed in 70% ethanol, and identified to the lowest possible taxonomic level. In a few cases arthropods were only identified to coarse taxonomic groups (e.g., family or genus); this was particularly true for spiders and immature stages of some orders. Therefore, some test groups could potentially contain multiple species, and we refer to the group as “various spp.” To be conservative, we count each of these groups as a single predatory taxon even though it is possible it contains more than one species.
To determine which milkweed-visiting arthropods can consume monarch eggs, we performed no-choice assays in 473 mL (16 oz.) deli-cup arenas (Solo Bare DM16R-0090). Larger predators (e.g., Mantodea and Opiliones) were placed in 946 mL (32 oz.) deli-cup containers (Solo Bare DM32R-0090) to allow for more natural movement. Field collected leaves of common milkweed were rinsed in tap water to remove any naturally occurring arthropods or debris. Late in the season when common milkweed was senescing, swamp milkweed (Asclepias incarnata L.) leaves of the same general shape and size were field collected and used in trials. Leaves of approximately 10 cm in length were placed diagonally against the side of the deli-cup arena to allow potential predators full access to forage on the top and bottom of leaf surfaces (Fig. 1). The petiole of each leaf was placed in a damp cotton ball to avoid desiccation during the experiment. A single monarch egg, obtained from a colony of wild monarchs, was lightly glued (Elmers® Glue-All) to the bottom side of each leaf, with a fine tipped paintbrush, to mimic the natural placement of eggs in nature. Field trials confirmed that naturally foraging predators readily consumed eggs attached in this fashion21. A single predator was placed in each deli-cup; then the cup was sealed with a perforated lid. Cups were placed in a climate-controlled growth chamber at 27 °C and 16:8 light cycle. Egg presence/absence was recorded at 48 h and each egg was also examined under a dissecting microscope for evidence of egg content removal by sucking arthropods. If an individual predator died during the assay, that replicate was discarded.
No-choice arenas used to test whether arthropods would consume monarch eggs or neonates. (a) Setup for most trials, in which the arthropod was placed on a milkweed leaf in a deli cup arena, with either a monarch egg or neonate for 48 h. (b) Setup for testing the predation potential of ants. Ant colonies housed in plastic containers were connected to arenas using clear tubing; ants accessed the tubing via a removable bridge. Top edges of colony containers and arenas were coated with fluon to prevent ants from escaping.
Following the same basic procedure, deli-cup predation arenas were used to assess potential predators of freshly hatched monarch neonates. Field collected A. syriaca or A. incarnata leaves were placed diagonally in the arena and a single neonate was placed on each leaf. Neonates were transferred to leaves with a fine-tipped paintbrush and observed under a microscope to ensure they were not damaged. Following placement, the caterpillars were left to acclimate for 10–20 minutes before a potential predator was added. Arenas were placed in the growth chamber, and neonate presence/absence and condition (alive or dead) was recorded at 48 h.
Monarch Butterfly Metamorphosis time-lapse FYV
FAQ
What do butterfly eggs look like?
Description: resembling a tiny golf ball, the eggs are laid singly, usually on the underside of a leaf. The egg is white when first laid, gradually become grey. Hatching period: 1 or 2 weeks. Where: either near the leaf midrib or and sheep sorrel, and occasionally dock leaves.
How long does it take for a butterfly egg to hatch?
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Irving, TXhttps://www.cityofirving.orgMonarch Butterfly Life Cycle | Irving, TX – Official WebsiteIn March and April the eggs are laid on milkweed plants. They hatch into baby caterpillars, also called the larvae. It takes about four days for the eggs to hat…
What to do if you find butterfly eggs?
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Determine the butterfly species:Knowing the butterfly species will help you identify the correct host plant, as different caterpillars have specific food sources.
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Observe the plant:Note the type of plant where the eggs are laid, as this will be the food source for the emerging caterpillars.
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Research:If you’re unsure, research the species of butterfly and its host plant requirements.
Does a butterfly lay eggs?
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After mating, female butterflies lay their eggs, often on or near the plants that their caterpillars will feed on.
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The butterfly life cycle consists of four stages: egg, larva (caterpillar), pupa (chrysalis), and adult butterfly.
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The eggs hatch into caterpillars, which are the larval stage of the butterfly.
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Pupa:The caterpillar then enters the pupa stage, forming a chrysalis, where it undergoes a transformation.
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Finally, the adult butterfly emerges from the chrysalis, ready to mate and lay eggs, continuing the cycle.
Do Butterflies lay eggs?
Butterflies are oviparous, meaning they lay eggs. They breed as many animals do—eggs from the female insect are fertilized by sperm from the male. The female butterfly stores the male’s sperm in a bursa, or sac, until she is ready to lay eggs. Depending on the species, females lay eggs one at a time, in clusters, or in batches of hundreds.
How many eggs does a butterfly lay?
The female butterfly stores the male’s sperm in a bursa, or sac, until she is ready to lay eggs. Depending on the species, females lay eggs one at a time, in clusters, or in batches of hundreds. Butterflies lay an average of between 100 to 300 eggs, although some species may only lay a few dozen, others can lay as many as a thousand or more.
How many types of butterfly eggs are there?
Use the photos below to identify 14 different types of butterfly eggs. Adding host plants to your garden will help attract butterflies and encourage them to lay their eggs, giving you the opportunity to find the eggs and witness the entire butterfly life cycle in your yard!
Do butterflies overwinter in eggs?
Some species of butterflies overwinter in eggs. This means butterfly embryos may take months to develop. To survive winter, those undergo diapause (a process of suspended development in an insect, invertebrate, or mammal embryo). Some of the butterfly species that overwinter as eggs include: Can You Care For Butterfly Eggs?
How do you find a butterfly egg?
To search for butterfly eggs, you will need a camera with a macro function, a magnifying glass, notebooks, and pens. You can start from the underside of the leaves, where female butterflies often feel safe to lay their eggs. Even though the upper side and the stems might be simpler to access.
Where can I buy butterfly eggs?
If you’re having trouble finding the eggs, purchase them from butterfly breeders. The popular species commonly sold include the Monarch butterfly eggs, Black swallowtail butterfly, and Sulphur butterfly. You can buy eggs from these breeders or online sources like Amazon. Tabitha is a nature lover who loves nothing more than a day spent outdoors.