Understanding Predators of Butterflies and Butterfly Larvae
Butterflies are among the most enchanting creatures to grace our gardens. They play a crucial role in pollination, making them an essential component of a healthy ecosystem. However, both butterflies and their larvae, the caterpillars, face numerous threats from predators that can significantly impact their populations to habitat loss. In this blog post, we’ll explore the common predators of butterflies and butterfly larvae, discuss methods to protect these delicate creatures, and suggest plants that can enhance larval success in your garden.
Common Predators of Butterflies and Butterfly Larvae
1. Birds
Birds are one of the most significant predators of butterflies and caterpillars. Species such as robins, warblers, wrens, blue jays, flycatchers, kestrels, and many more birds are known to feast on caterpillars. The caterpillars are rich in protein making them essential to a birds diet.
There are over 100 species of birds that feed on butterflies, moths, and caterpillars. Adult butterflies are at risk, particularly from small, fast-flying birds like swallows.
On the flip side of this topic, some caterpillars provide the very rich carotenoids which help baby birds form pigmentation for their growing feathers.
2. Wasps
Wasps, particularly paper wasps and parasitic wasps, are notorious for preying on caterpillars. Parasitic wasps lay their eggs inside caterpillars. Some will attach their eggs to the tops of caterpillars. Then the developing wasp larvae feed on the caterpillar from the inside out, eventually killing it.
Paper wasps, on the other hand, hunt caterpillars to feed to their own young. I have tried hard to protect my Monarch caterpillars from paper wasps. Previously, I have put the caterpillars in an enclosure that blocks the paper wasps from getting them. There are many types of butterfly “cages”/enclosures to pick from where you can protect your caterpillars also.
This past year I have tried to leave my paper wasps alone even though I am a huge butterfly lover. Usually, I have to fight them off of eating my Monarchs. However, earlier this summer I had a huge infestation of fall webworms. I would tear open the webworms webs and let the wasps get to them and eat them. Ever since then I have really tried hard to find more peace with the paper wasps.
3. Spiders
Spiders pose a threat to both butterflies and their larvae. Orb-weaver spiders, for instance, catch butterflies in their webs. Some ground-dwelling spiders, like wolf spiders, may also prey on caterpillars crawling along the soil or plant stems.
I have also seen how spiders will suck the juices from the chrysalis of butterflies. The chrysalis will then turn black meaning that the butterfly has meet its untimely death. Not something that gardeners like to see.
While we may want to protect caterpillars from spiders I need to mention that spiders are some of the best creatures that help control populations of some of the “bad bugs” found in the garden.
Spiders also pollinate some flowers. I consider them some of the unsung heroes that help with pollination. Believe it or not spiders are some of the most important species that we can have around.
4. Ants
Ants are tricky….Certain species of ants are known to attack and consume butterfly eggs, larvae, and even pupae. Carpenter ants and fire ants are particularly aggressive and can decimate butterfly populations if left unchecked.
However, there are some species of ants that will protect caterpillars. Some butterfly families such as the blues, the hairstreaks, and coppers will secret a nectar-like fluid from glands all over their bodies that the ants will feed on and in-turn they will protect the caterpillars.
5. Mantises
Praying mantises are skilled hunters that will readily catch and eat both butterflies and their larvae. They use their powerful forelegs to snatch their prey with lightning speed, making them a formidable threat in the garden.
Praying Mantids will eat just about anything. They love to dine on not only caterpillars, but also on leaf hoppers, aphids, flies, honeybees, crickets, and moths. They will also feed on each other if they are hungry enough.
Mantids are territorial and mostly live a solitary life.
6. Mammals
Small mammals, such as mice, shrews, and even some species of bats, can be predators of butterfly larvae. These mammals tend to feed on caterpillars during their nighttime foraging, making it difficult to spot and protect against them.
Non-Animal Predators That Kill Monarchs and Other Butterflies
There are a multitude of other things that can kill Monarchs and other butterflies. Predators of Butterflies are not always other animals. Some predators of butterflies are parasites such as O.E. (Ophryocystis elektroscirrha) that affects Monarchs, Queens, and Soldiers.
Read more about O.E. and how to help Monarchs: Where Do Monarch Butterflies Migrate To?
There are also many other things that affect butterflies such as, lack of food, lack of resting places, lack of water in certain areas (or places to land to get that water), insecticides, and lack of nesting areas.
Protecting Butterflies and Their Larvae from Predators
Given the numerous threats butterflies and their larvae face, gardeners can play a vital role in their conservation by implementing strategies to protect them. Here are some effective ways to safeguard these delicate creatures:
1. Provide Safe Habitats
Creating a butterfly-friendly habitat is the first step in protecting butterflies and their larvae. Incorporate dense plantings and layers of vegetation, which offer caterpillars and butterflies shelter from predators. Include shrubs, tall grasses, and ground covers to provide hiding spots.
I like to mix in my butterfly host and larval plants with other plants to help protect the butterflies (and moths).
2. Use Physical Barriers
Physical barriers, such as netting or mesh, can be an effective way to protect caterpillars and pupae from predators. Covering host plants with fine mesh netting can prevent birds, wasps, and other predators from accessing the larvae. Be sure to secure the netting tightly to prevent any gaps where predators could enter.
For many years I have used a butterfly enclosure that helps protect Monarch caterpillars from predators- mainly wasps. I keep an eye out for eggs on the Milkweed plants and then wait for them to hatch. I usually wait until a day or two after they hatch before I try to move them to my enclosure. They are almost too fragile to move them before that.
In addition, if using an enclosure to help raise butterflies be sure to always have a fresh supply of food for the larva. They will not need water during this stage of their life cycle.
3. Introduce A Variety of Plants
Planting a variety of plants can help deter predators and create a more balanced ecosystem in your garden. For example, planting a variety of plants will help bring in a diverse selection of insects into your garden.
You will have both beneficial insects and some predators in your garden that ultimately balance out the ecosystem.
Strong-scented herbs like dill, fennel, and parsley will attract many different pollinators into your garden. Also, you can try planting a variety of herbs to help ward off some of the predators that may not like some of the stronger herbs.
4. Create a Butterfly Shelter
Building a butterfly shelter or “butterfly house” can provide adult butterflies with a safe place to rest and lay eggs. These shelters can be constructed using wood or bamboo and should include narrow slits for the butterflies to enter.
Place the shelter in a sunny, sheltered spot near nectar-rich plants.
5. Encourage Natural Predators
While it may seem counterintuitive, encouraging certain natural predators can help maintain a balance in your garden. Ladybugs, for example, feed on aphids and other small insects that can compete with caterpillars for food. Aphids will suck the juices out of the host plants eventually killing it.
Green Lacewings will do similar predator control. They can eat up to 200 aphids in one week.
Similarly, birds that do not prey on butterflies can help keep insect populations in check without threatening butterfly larvae.
6. Minimize Pesticide Use
Chemical pesticides can harm not only pests but also beneficial insects, including butterflies and their larvae. Opt for organic pest control methods, such as neem oil, insecticidal soap, or natural predators like ladybugs and lacewings, to keep your garden healthy without endangering butterflies.
I have been known to handpick predatory insects or insects that can cause an enormous amount of damage, such as the fall webworm. I don’t like to touch bugs with my hands so I tend to use gardening gloves when I do my hand picking. I have heard of others using a handheld dust buster but, I have never tried it.
7. Provide Nectar and Host Plants For Butterflies
Ensuring a steady supply of nectar and host plants is crucial for supporting butterfly populations. Nectar plants provide food for adult butterflies, while host plants are used by butterflies to lay their eggs and feed the caterpillars. By planting a variety of these plants, you can create a haven for butterflies and increase the chances of larval success.
Another thing to think about is bloom time. You may want to plan to have host and nectar plants that bloom at different times. When one plant is starting to have the flowers fade another plant can be ready to begin flowering for a constant supply of flowers. It looks nice when plants are always flowering in your garden, too.
Check out this post about Gardening For Butterflies to learn more.
Plants That Improve Larval Success For Caterpillars
Planting the right plants is essential for supporting butterfly larvae. I like to use mostly native plants for my area. Not only will those plants do better in their native environment but they will help the overall success of having more butterflies in your yard.
Also, having natives in your garden will attract the native butterflies that are within your area.
When looking for the right plants to help larvae survive grow plants that are the larvae host plants. This is the type of plants that the butterflies will lay their eggs on. When the larvae hatch they will eat the host plant. Be prepared for these plants to get eaten – a lot.
Here are some top choices that can help improve larval success in your garden, in no particular order:
1. Milkweed (Asclepias spp.)
Milkweed is the host plant for monarch butterflies, making it an essential addition to any butterfly garden. The caterpillars feed exclusively on milkweed. An added bonus is that the plant contains toxins that make the caterpillars unpalatable to many predators.
Milkweed is also a nectar plant for many other butterflies and bees. There are many varieties of Milkweed. Be sure to get the Milkweed that is native to your area.
If you want to learn more about Monarchs check out this post: Where Do Monarchs Migrate?
2. Dill (Anethum graveolens)
Dill is a favorite host plant for black swallowtail butterfly larvae. The strong scent of dill can also help deter some predators, making it a dual-purpose plant in your garden. I love having dill in the garden.
The leaves of dill are somewhat lacey and dainty. This helps the caterpillars camouflage when they are on this plant. It does help that they have striped bodies making it hard for their predators to see them.
3. Fennel (Foeniculum vulgare)
Like dill, fennel is another host plant for black swallowtail caterpillars. Its feathery foliage provides a perfect hiding spot for larvae, protecting them from potential threats.
Fennel can grow as tall as 5 feet. The yellow flowers are also great for pollinators other than swallowtails. Fennel is drought tolerant and easy to grow. Both dill and fennel are easy to start from seed.
4. Parsley (Petroselinum crispum)
Parsley is a common herb that serves as a host plant for swallowtail caterpillars. It’s easy to grow and can be planted in both garden beds and containers, making it accessible for all types of gardens.
Caterpillars will stay on the parsley plants during their entire larval life cycle. The plant grows back quickly making it perfect for any herb/pollinator garden.
Parsley is a cool season plant and will begin to die when the weather gets really hot during the summer months.
5. Oak Trees
Many of the oak trees throughout the U.S. are host plants to the hairstreak and other butterflies. Oak trees come in a wide variety so be sure to pick the one for your area that will be a good fit for the types of butterflies you want.
In addition to using oak trees as a host plant Hairstreak butterflies will also lay their eggs in the dead leaves that are on the ground under the oak trees.
The butterflies that use oaks as host plants are:
- Banded hairstreak
- Northern hairstreak/Texas Hairstreak/Autolycus hairstreak
- Red-Banded hairstreak
- Juvenal’s Duskywing
- Horace’s Duskywing
6. Passionflower (Passiflora spp.)
Passionflower is the host plant for several species of butterflies. Its intricate blooms also attract a variety of other pollinators, making it a beautiful and functional addition to the garden.
Passionflower is a climbing vine that has either white or purple flowers. The flowers have a lovely fragrance to them. However, it does not make a good cut flower since the flowers will not live long off of the vine (I have tried).
Here are a few of the butterfly species that use Passionflower as a host plant:
- Gulf fritillary butterfly (Agraulis vanillae)
- Julia (Dryas iulia)
- Zebra (Heliconius charitonius)
7. Violets (Viola spp.)
Violets are the host plant for the Great Spangled Fritillary and several other species of butterflies. They thrive in shady areas, providing a valuable resource for butterflies in less sunny parts of the garden.
In the south violets are an annual, however, in zones 3-8 you can have violets as perennials. The violets in the south grow mainly in cooler temperatures and will fade when the temperatures begin to get warm.
8. Willows (Salix spp.)
Willows are host plants for several species of butterflies, including the Mourning Cloak and Viceroy. These trees and shrubs provide both food and shelter for butterfly larvae, particularly in wetter areas of the garden.
Some willows can get up to 100 feet tall depending on the variety. Be aware of which variety you are getting when shopping for them. Some willows come in a much smaller size making them the perfect size for gardens that don’t have as much space.
9. Tulip Tree (Liriodendron tulipifera)
The tulip tree is a host plant for the Eastern Tiger Swallowtail butterfly. Its large leaves provide ample food for larvae, while its towering height offers protection from some ground-dwelling predators.
Tulip trees are native to the eastern United States. They grow up to 150 feet tall. These trees are easily confused with the Saucer Magnolia (Magnolia X soulangeana) which is a member of the Magnolia family. The Saucer Magnolia will only get around 25 feet tall and has light purple flowers. The flowers of the Tulip Tree are a buttery yellow.
10. Spicebush (Lindera benzoin)
Spicebush is the host plant for the Spicebush Swallowtail butterfly. This shrub is relatively low-maintenance and can thrive in a variety of soil conditions, making it a versatile choice for butterfly gardens.
The Promethean Moth also will use the spicebush as a host plant.
The Spicebush Swallowtail will eat the Sassafras Tree as well.
11. Grasses
Grasses that are native to your area are perfect for certain types of butterflies that need those grasses to survive. Many of the grasses that fall into this category are bluestem species, wild oats, purpletop, St. Augustine, and Bermuda grass.
Some skippers like the Celia’s Roadside Skipper (Amblyscirtes celia), and Julia’s Skipper (Nastra julia) need St. Augustine grass as one of their food plants.
Bermuda grass is an essential food plant for the Sachem (Atalopedes campestris) skipper, the Southern Skepperling (Copaeodes minimus), and for the Whirlabout (Polites vibex).
The Swarthy Skipper (Nastra lherminier) uses the plant Little bluestem grass as its food plant.
Conclusion
By understanding the predators that threaten butterflies and their larvae, and by taking proactive steps to protect these delicate creatures, gardeners can play a crucial role in butterfly conservation. Incorporating protective measures and planting the right plants can significantly improve larval success and help maintain healthy butterfly populations in your garden. Remember, every small effort counts, and with the right approach, your garden can become a safe haven for these beautiful and essential pollinators.
Whether you’re an experienced gardener or just starting out, consider dedicating a portion of your garden to support butterflies and their larvae. Not only will you be contributing to the preservation of these important species, but you’ll also enjoy the added beauty and life they bring to your outdoor space. Happy gardening!
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