In the opening paragraphs, it’s important to quickly answer the main question being asked: Do spiders eat monarch butterflies? The short answer is yes, spiders do sometimes eat monarch butterflies. Monarch butterflies have many predators, including spiders, that help keep their population in balance. However, most spiders do not specifically target monarch butterflies and monarchs have defense mechanisms to avoid being eaten.
Do Spiders Eat Butterflies in General?
To understand if spiders eat monarch butterflies specifically, it helps to first look at if spiders eat butterflies in general. The answer is yes, many spiders do prey on butterflies. Spiders are predators that feed mainly on insects. Butterflies make up part of the insect diet for many spiders.
There are over 47,000 spider species worldwide. Most spiders are generalist predators that eat a wide variety of insect prey. Butterflies, with their bright colors and daytime activity that exposes them, make them easy targets for hungry spiders.
Spider species known to eat butterflies include:
- Orb weaver spiders
- Jumping spiders
- Crab spiders
- Wolf spiders
- Lynx spiders
- Green lynx spiders
These ambush or hunting spiders will capture and eat any butterflies unlucky enough to fly or land too close to their webs and hiding spots. The remains of butterfly wings have been found in the webs of orb weaver spiders.
Do Specific Spider Species Target Monarchs?
While many spiders eat butterflies in general, do any species specifically target monarch butterflies? There are no spider species that exclusively prey on monarchs. However, some common backyard spiders likely include monarchs as part of their broad diets.
For example, the spiny orb weaver spider is known to eat bees, flies, grasshoppers, and butterflies. With monarchs being a common butterfly species, spiny orb weavers probably eat them when the opportunity arises. Jumping spiders, crab spiders, and lynx spiders also opportunistically prey on many insects and butterflies, including monarchs.
How Do Spiders Catch and Eat Butterflies?
To understand how spiders prey on monarchs and other butterflies, it helps to look at their general butterfly hunting strategies:
- Webs: Orb weaver spiders use their intricate webs to passively trap butterflies. The webs are spun with sticky silk strands that butterflies get caught on as they fly by. Once trapped, the spider approaches to bite and wrap the butterfly in more silk before eating.
- Camouflage: Ambush predators like crab spiders rely on camouflage to remain unseen by butterflies. They wait perfectly still for a butterfly to land near them. Then they strike quickly to grab the butterfly with their front legs and inject venom.
- Speed: Jumping spiders and lynx spiders actively hunt for butterfly prey. Their quick reflexes and jumping ability allow them to pounce on butterflies from both short and long distances.
- Venom: All spiders use venom injected through a bite to paralyze and start digesting their butterfly prey. The venoms break down proteins, fats, and carbs from the inside out.
These strategies allow spiders to catch and consume nutritious butterflies, including monarchs, with relative ease.
Do Monarch Caterpillars Get Eaten by Spiders?
It’s not just adult monarch butterflies that face threats from spiders. The caterpillar stage is also vulnerable to spider predation.
Caterpillars lack wings and the same self-defense mechanisms as adult butterflies. Their soft bodies make for an easy, nutritious meal for spiders.
Spider species known to eat monarch caterpillars include:
- Jumping spiders
- Crab spiders
- Lynx spiders
- Wolf spiders
- Orbweavers
These ambush or hunting spiders will devour any caterpillars they come across while foraging. Jumping spiders in particular are major predators of monarch caterpillars.
However, spiders face their own challenges catching caterpillars. Caterpillars have camouflaged coloration that helps them blend in on milkweed plants. During the day, they also keep a low profile hidden under leaves near the base of plants.
Do Monarch Butterflies Have Defenses Against Spiders?
Although many spiders prey on monarchs, these butterflies have evolved some defenses to help them avoid becoming lunch:
- Chemical defenses: Monarch caterpillars feed exclusively on milkweed plants. Milkweeds contain toxic cardiac glycosides that make monarch caterpillars and adults poisonous to many predators, including some spiders.
- Bad taste: If a spider tries to eat a monarch caterpillar or butterfly, it gets a mouthful of foul-tasting chemicals. This bad taste can deter further attempts to eat monarchs.
- Warning coloration: Adult monarchs have bright orange wings that act as a warning signal. Predators learn to associate the color pattern with bad taste and toxicity.
- Quick reflexes: Monarch butterflies have quick instinctive reactions to dodge attacking spiders and other predators.
- Erratic flight: Monarchs engage in erratic, unpredictable flight patterns. This makes it hard for spiders to accurately strike or web them.
While not completely spider-proof, these defenses likely prevent many spiders from viewing monarchs as ideal prey.
Do Spiders Have a Significant Impact on Monarch Populations?
On an individual level, spiders do eat both monarch caterpillars and butterflies. However, research suggests that at a population level, spiders have a minor impact on overall monarch numbers compared to other factors.
One research study looked at predators of monarch eggs and caterpillars on milkweed plants. It found that spiders caused less than 2% of monarch deaths. Other insects like wasps, ants, and bugs were far greater threats.
For adult monarchs, parasitism by tachinid flies and Ophryocystis elektroscirrha (OE) disease cause higher mortality rates than spider predation.
Habitat loss also ranks as a much higher risk to monarchs than spider predation. The monarch population in North America has declined over 80% in the last 20 years mostly due to:
- Reduced milkweed food sources from greater herbicide use
- Increased land development
- Climate change
These environmental stressors have a much bigger impact on the monarch’s struggle for survival than spiders do.
Conclusion
In conclusion, spiders do prey on both monarch caterpillars and butterflies. Common spider families like orb weavers, jumping spiders, crab spiders, and lynx spiders will eat monarchs when given the chance. However, monarch chemical defenses and erratic movements help many avoid being eaten.
While individual monarchs get eaten by spiders in nature, research shows that at a population level spider predation causes minimal damage. Habitat loss and disease are much greater risks to the monarch’s survival as a species. So in the context of all the threats they face, spiders rank low on the list of concerns for monarch butterfly conservation.