Giant swallowtail caterpillars are known for their voracious appetite and can cause significant damage to plants and trees. While these caterpillars eventually transform into beautiful, beneficial pollinators, it’s important to manage their populations when they pose a threat to your garden or landscape.
There are several effective methods to control giant swallowtail caterpillars, including natural predators, manual removal, and selective use of insecticides. In this article, we’ll explore these techniques and provide helpful tips for keeping your plants safe and healthy. Remember, it’s crucial to strike a balance between protecting your plants and supporting the natural ecosystem.
Understanding Giant Swallowtail Caterpillars
Life Cycle of the Giant Swallowtail Butterfly
- Eggs: The female butterfly lays yellow eggs on the host plants.
- Larvae: The caterpillars hatch and go through several instar stages.
- Pupae: Caterpillars form a chrysalis as they prepare to become butterflies.
- Adults: Adult giant swallowtails emerge from the chrysalis and start the cycle again.
These caterpillars are the larval stage of the giant swallowtail butterfly (Papilio cresphontes). They have a unique defensive organ called the osmeterium. It releases a foul smell to ward off predators.
Key Features and Characteristics
- Coloration: Blotchy brown-and-white pattern
- Size: 1.5-2 inches when mature
- Resemblance: Looks like a bird dropping
- Defense: Osmeterium
These caterpillars can be identified by their blotchy brown-and-white pattern, which helps them blend in and avoid predators. They can grow up to 1.5-2 inches when mature.
Habitats and Host Plants
- United States, mainly Florida
- North America
- Citrus trees
- Other plants in the Rutaceae family
Giant swallowtail caterpillars are native to the United States and feed primarily on citrus trees, earning them the nickname “orange dogs.” They are especially common in Florida and other areas of North America where citrus trees are abundant. Host plants are crucial for their survival as they lay their eggs and develop into adult butterflies.
Identifying Damage Caused by Giant Swallowtail Caterpillars
Recognizing Injury to Garden and Citrus Plants
Giant swallowtail caterpillars, also known as Papilio cresphontes Cramer, primarily target citrus plants, causing visible damage. Here are a few symptoms of their presence:
- Leaves: Skeletonized, partially eaten, or curled leaves.
- Fruit: Fruit may drop prematurely or have visible chew marks.
For example, you might see the edges of a lemon tree’s leaves eaten away or chewed holes in orange leaves.
Signs of an Infestation
Usually, it’s easy to spot a giant swallowtail caterpillar infestation:
- Caterpillars: They are brown or green, and resemble bird droppings, making them difficult to spot on the plant itself.
- Eggs: Tiny, orange-yellow orbs found on the undersides of leaves.
Comparison of damage caused by different pests:
|Skeletonized leaves, damaged fruits
|Large milkweed bug
|Deformed, yellowed leaves
|Defoliation, chewed leaf edges
|Defoliation, chewed leaf edges
Pros and Cons of Giant Swallowtail Caterpillars
It’s essential to understand the positive and negative aspects of giant swallowtail caterpillars before trying to eradicate them:
- Beautiful adult butterflies
- Natural predator control
- Damage to citrus plants and gardens
- Potential loss of fruit production
Natural Methods to Control Swallowtail Caterpillars
Using Bacillus Thuringiensis (Bt)
Bacillus Thuringiensis (Bt) is a naturally occurring bacteria that’s effective against caterpillars, including giant swallowtails. Apply Bt to affected plants using a spray bottle. Caterpillars ingest Bt when feeding on leaves, causing them to stop eating and eventually die.
- Natural and safe for the environment
- Doesn’t harm beneficial insects
- Must be reapplied after rain or watering
- Can affect non-target caterpillars
Introducing Beneficial Predators
Invite beneficial predators like birds, ladybugs, and parasitic wasps to your garden:
- Install birdhouses and bird baths
- Add plants that attract beneficial insects
These predators help control giant swallowtails and other pests.
Hand-Picking and Home Remedies
Hand-picking caterpillars can be an effective way to control them. Do this daily for the best results. Dispose of the removed caterpillars properly.
There are also home remedies to help control giant swallowtails:
- Neem oil: Mix with water and spray on plants
- Pepper and garlic mixture: Crush garlic and pepper, add to water, and spray on plants
- Soap and water solution: Mix a few drops of liquid dish soap with water and spray on plants
Use these remedies sparingly to avoid harming your plants.
|Bacillus thuringiensis (Bt)
|Natural, safe for the environment, targets caterpillars
|Must be reapplied, can affect non-target caterpillars
|Controls various pests, adds biodiversity to the garden
|Takes time to establish predator populations
|Immediate results, no chemicals
|Time-consuming, daily monitoring needed
|Inexpensive, uses common household items
|Can harm plants if overused
Chemical Control Techniques for Caterpillar Management
Commercial Sprays and Pesticides
One effective way to manage giant swallowtail caterpillars is by using a chemical control agent like Sevin. Sevin is a widely-used pesticide that can help control caterpillar populations on your plants.
- Pros: Fast-acting, effective against various pests
- Cons: May harm beneficial insects, multiple applications may be needed
|Chemical Control Agent
|Impact on Beneficial Insects
Precautions and Safe Usage
When using chemical control methods, it is crucial to adhere to safe usage practices.
- Read and follow the product label’s instructions
- Wear protective clothing, including gloves and eye-wear
- Avoid spraying during windy conditions or when bees are active
- Properly dispose of any leftover chemicals and containers
By following these guidelines, you can safely and effectively manage giant swallowtail caterpillars while minimizing negative impacts on the environment and beneficial insects.
Nurturing and Supporting Swallowtail Butterflies
Creating a Butterfly-friendly Garden
To support swallowtail butterflies, you can create a garden with plants suitable for both caterpillars and adult butterflies. Some popular host plants for the caterpillars include:
For the giant swallowtail caterpillars, you can plant:
- Prickly ash (Zanthoxylum americanum)
- Hercules club (Ptelea trifoliata)
- Wild lime
- Common rue
Adult butterflies need nectar-producing plants to feed on. You can use floral tubes to provide them with an adequate food source.
Caring for Swallowtail Caterpillars and Butterflies
When caring for swallowtail caterpillars, keep them in a caterpillar cage to protect them from predators like birds. Watch for giant swallowtail eggs and make sure the cage is spacious enough for the growing caterpillars.
Monitor the chrysalis formation stage and maintain a clean environment. Keep plants healthy by removing dead leaves and disposing of them properly.
To prevent diseases, you can pour boiling water over affected plants to kill bacteria and other pathogens. Check on your caterpillars regularly and ensure their habitat is safe and suitable for growth.
Remember that providing proper care for both caterpillars and butterflies contributes to a thriving butterfly garden.
Dealing with Other Garden Pests
Controlling Snails and Slugs
One efficient method to reduce the number of garden pests is to hand-pick them during a walk in your garden. For instance, deposit snails and slugs in a bottle of water and empty it when necessary.
Burlap sacks can also be placed around the garden, providing a hiding spot for these pests. Simply check the sacks daily, collect and dispose of the hidden snails and slugs.
- Environmentally friendly
- Easy to apply
- May not eliminate all pests
Managing Hairy Caterpillars and Other Insects
Hairy caterpillars, such as monarchs, can also be removed manually. However, wear gloves to avoid irritation from their hairs.
When managing garden insects, note that some, like predatory snails, are beneficial in controlling other garden pests.
|Environmentally friendly, easy to do
|Time-consuming, may not be 100% effective
|Natural solution, efficient
|Need to introduce and maintain population
- Hand-pick snails, slugs, and hairy caterpillars
- Use burlap sacks to trap snails and slugs
- Consider introducing predator snails in your garden to manage pests naturally
- When dealing with hairy caterpillars, wear gloves for protection
- Be mindful of the environment and avoid harming beneficial insects
Preventing Future Infestations
Practices for a Healthy Garden
- Plant garlic: Planting garlic around your garden helps deter giant swallowtail caterpillars. Garlic’s strong smell repels pests.
- Rotate crops: Rotate your crops and avoid planting citrus family plants in the same location every year. This helps reduce the likelihood of infestations in the future.
- Encourage beneficial insects: Attract predators like ladybugs and lacewings to your garden. They help keep giant swallowtail caterpillar populations under control.
Keeping a Close Eye on Plant Health
- Monitor plants: Regularly inspect your garden plants, especially those in the citrus family, for caterpillar eggs and remove them promptly. Giant swallowtail caterpillars can severely damage citrus plants.
- Check for glandular trichomes: Kansas gardeners should keep an eye out for glandular trichomes on the undersides of leaves, which may attract giant swallowtail caterpillars.
- Healthy plants: Maintain overall plant health as healthier plants are less susceptible to caterpillar infestation. Regular watering, proper fertilizing, and pruning are essential for a healthy garden.
Pros & Cons of Garlic as a Pest Deterrent
|No harmful chemicals
|Requires regular replanting
|Easy to grow
|May not work for all pests
Remember to practice these healthy gardening techniques and keep a close eye on your plant health to prevent future infestations of giant swallowtail caterpillars in your garden.
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Orange Dog
Bird Poop Caterpillar
I believe I may have found the Bird Poop Caterpillar on my lemon tree here in Kansas City. I see pictures of the moth but can not find pictures of the caterpillar. What do you think?
The caterpillar of the Giant Swallowtail Butterfly resembles bird droppings and eats leaves of citrus trees. It is commonly called the Orange Dog.
Letter 2 – Orange Dog
Can you tell me what this one is…
Found on an orange tree in Friendswood , Texas . It rears aggressively when touched.
The Caterpillar of the Giant Swallowtail is known as the Orange Dog because of its favorite food source. Those orange horns are revealed when the caterpillar is disturbed allowing it to emit a foul odor, a defense mechanism. The caterpillar also resembles bird droppings which helps it prevent being eaten. Great photo.
Letter 3 – Orange Dog
Giant Swallowtail caterpillar and unknown caterpillar
I live in central Mexico in Guanajuato state and found this Giant Swallowtail caterpillar crawling across our porch. I ID’d him from the web and found that he belonged on our lime tree that’s many feet from where he was seen crawling. Today he’s happily munching away, though another one I spotted on the tree when I replaced him is no where in sight. I see that you do have a picture of a Giant Swallowtail caterpillar but I thought you might like one without the horns up. He sported his twice when I went to place him back on the lime tree leaves. Kinda cool to see. Otherwise, he looks like bird droppings (which I know is his clever camouflage), especially when he’s still. The other critters I also found on the same lime tree. It seems to be home to several insect species, including a variety of ants, jumping spiders and the itinerant bee or wasp. I spotted these little fuzzy white guys on the underneath side of some of the leaves toward the base of the tree. They’re about 1/4″ in diameter as far as I could tell. They were in kind of a precarious place so I couldn’t get really close. I don’t see anything on your site that resembles them. They’re too small for an asp, I think, and don’t really look like that. Any clues?
We are happy to post your Giant Swallowtail Caterpillar, commonly called an Orange Dog. Your other image came through as garbage and we can’t view it.
Letter 4 – Orange Dog
Snake Eyes and Forked Tongue
We discovered about ten caterpillars on our lemon tree in Texas. They resemble a small snakes head (false eyes) like some Swallow Tails. When touched…surprise two small bright orange appendages flick out; looks just like a snake’s forked tongue. Any ideas? Now that I’ve found your wonderful site, I’ll get some pictures. One is already in the pupae stage. Here are a couple photos. They are only about 1 1⁄2 inches in length. Chrysalis photo to follow; it’s night here now, so I’ll wait until tomorrow. Little buggers are wreaking havoc on my lemon tree:-). Also, do you have any tips on relocating the pupae? I want to move it to a container in order to observe it when it emerges. Thank you for your time.
Keith L. Wagoner
Commander, U.S. Navy
Hi Commander Keith,
This is an Orange Dog, the caterpillar of the beautiful Giant Swallowtail. Many people, us included, think they resemble bird droppings. The orange scent organ is the osmetrium. Try pruning the branch away from the tree to relocate the chrysalis. Thw Swallowtails create a silken girdle for the pupa so that it is upright. Removing the chrysalis without the branch could damage the creature.
Letter 5 – Orange Dog
Are you still identifying caterpillars? I found this strange looking caterpillar on my lemon tree. We live in Southern California, about 25 miles inland from San Diego. My daughter thought it looked like a bird dropping! It’s about 3 inches long and sort of has a face. Thanks,
The caterpillar of the beautiful Giant Swallowtail is sometimes called the Orange Dog. They do look like bird droppings.
Letter 6 – Orange Dog
Subject: caterpillar on orange trees
Location: Gulf Breeze, FL
October 15, 2012 7:59 pm
I search all over the internet for this caterpillar that is eating up a young orange I have. Can you tell me what kind of caterpillar this is and what the life cycle is.
Signature: Dot Desrosiers
This is the caterpillar of a Giant Swallowtail, and it is sometimes called an Orange Dog because of its preferred food plant. The few leaves that you lose to the caterpillars feeding should be well balanced by the beauty that the adult Giant Swallowtail brings to your garden. Orange Dogs mimic bird droppings as a means of camouflage.
Thank you for your quick response. How log before they turn into a cocoon and then a butter fly. I can’t wait to see them.
Here is a nice web page devoted to raising Swallowtails in captivity called Great Stems. We are tying to find more specific details on the time spent in the chrysalis for the Giant Swallowtail, and this comment is made regarding the Two Tailed Swallowtail: “The Two-Tailed Swallowtail can take many months before it emerges from its chrysalis.” J.J. Cardinal’s Wild Bird and Nature Store provides this information: “Your giant swallowtail will hatch from its chrysalis in 18 to 20 days. Release it within the second day.” With eclosion or emergence of an adult butterfly or moth, much depends upon weather and temperature conditions. If conditions are not favorable, then the insect will remain in the pupal stage for longer periods of time.
You’re great! Great resources for information on my Orange Dogs. Have a great day!
Thank you so much.
Letter 7 – Orange Dog
Subject: what is this?
Location: tucson, az
December 4, 2012 1:46 pm
found this caterpillar on my orange tree, what kind is it?
This is the caterpillar of the Giant Swallowtail and it is commonly called an Orange Dog. Though they feed on the leaves of citrus, we doubt they will ever be plentiful enough to cause a problem. The adult Giant Swallowtail is a beautiful butterfly. It is native to eastern North America, but its range has expanded to the eastern states with the cultivation of citrus trees. Citrus is not its native host plant, but it has easily adapted its preferences to be able to flourish with the cultivation of citrus.
Letter 8 – Orange Dog
Subject: Caterpillar in AZ
Location: Mesa, AZ
April 21, 2013 1:44 pm
Found this caterpillar today, April 21, 2013 on my hat and at first thought it was a bird dropping. On closer inspection it looked like a half of a lizard, without legs. It’s about 1 1/4” long with a brown and white coloring. Never seen one like this before.
When first we received your email, we didn’t read it and immediately wrote back that the images had not attached. Thank you for sending the images. If we had read you email, we could have answered your question with a 97% accuracy, because your verbal description marvelously describes the Orange Dog, the caterpillar of the Giant Swallowtail, a North American butterfly that adapted to the cultivation of citrus in Florida, and when citrus was grown more widely, including in backyard and porch gardens, the Giant Swallowtail was able to expand its range all the way through Arizona to California. Your email did not indicate if it was found near an orange, lime or other citrus tree. If you disturb the Orange Dog, it will reveal its osmeterium, an orange fork-shaped organ that releases an odor some predators might find repulsive. See BugGuide for a matching photo, and you can also see BugGuide’s information page on the Giant Swallowtail for more information.
Daniel, thank you for your assistance. We have several citrus trees in our yard and I moved it from my hat back to one of the orange trees. My daughters are looking forward to the possiblity of seeing the Giant Swallowtail flying around our back yard.
Letter 9 – Orange Dog
Subject: Say What??
Location: Chunchula, Mobile County, Alabama
May 11, 2014 6:28 am
This is the second of these I have found hanging around on our citrus trees. Never seen anything like it before. Got any ideas?
Signature: Thomas J. Kelly
This is the caterpillar of a Giant Swallowtail, commonly called an Orange Dog. This native species has adapted quite well to feeding on leaves of introduced citrus trees, which has resulted in an increase in the range of the species as the cultivation of citrus has spread in North America. This formerly eastern butterfly is now a common sight in Los Angeles where citrus is often cultivated in backyards. The Orange Dog has two interesting means of protecting itself from predators. First, it resembles the droppings of a bird, so predators will often overlook the Orange Dog. If that fails, the Orange Dog, like many other caterpillars in the family Papilionidae, possesses a forked organ known as an osmeterium. When disturbed, the organ is exposed and it releases an odor some predators find offensive.
Letter 10 – Orange Dog
Subject: New pet at new home
Location: Encinitas, CA
July 7, 2014 9:02 pm
Hi, my husband and I just moved to Encinitas, CA (San Diego County) today (July 7th) and found this guy welcoming us at our new home, munching on our lemon tree. He’s a cutie (and a little scary with that face!) and we want to let him chow down, but want to make sure he’s not an invasive/destructive species. Any ideas what he is?
Signature: Allison in Encinitas
This is an Orange Dog, the caterpillar of the Giant Swallowtail, the largest butterfly found in southern California. Giant Swallowtails are native to the eastern part of North America, however, when citrus was introduced as a crop in Florida, the Giant Swallowtail adapted to feeding on the leaves of the introduced trees. As the cultivation of citrus spread in North America to include Arizona and Southern California, the Giant Swallowtails expanded their range as the food was readily available. though not theoretically native to Southern California, the Giant Swallowtail is native to North America, the the damage caused by the feeding caterpillars is relatively insignificant. If you disturb the Orange Dog, you will likely get to see the osmeterium, a forked organ that releases a scent to deter predators.
Letter 11 – Orange Dog
Location: Palm Springs California
March 24, 2015 6:20 pm
It looks like a larvae of a moth
Letter 12 – Orange Dog
Subject: Larva on lemon tree
Location: Riverside, CA
November 2, 2015 4:41 pm
I was wondering if this is a destructive bug or a benifical. It just showed up on my lemon tree in Southern California. The tree has curling leaves like it has leaf miners of some sort. How shall I protect my plant?
Signature: Thank you for any help. Allison
Destructive and Beneficial are somewhat relative terms when it comes to phytophagous or plant feeding insects. This is an Orange Dog, the caterpillar of a Giant Swallowtail. It is theoretically not a species native to California, but rather native to the North American Southeast, but with the cultivation of citrus in Florida and then elsewhere in the warmer climates of North America, the species adapted to feeding on the leaves of the cultivated citrus and its range expanded with that cultivation. Giant Swallowtails were first reported in California in the 1990s and they are now quite established. In our opinion, the loss of leaves from an individual caterpillar is a minor sacrifice to the gardener considering the beauty of the adult butterfly, which is the largest butterfly found in California. The coloration of the Orange Dog resembles the pattern of a bird’s droppings, creating an effective means of camouflage for the tasty caterpillar. The curling leaves and leaf miners are not related to the Orange Dog and they pose a more serious threat to your lemon than the Orange Dog poses.
Thank you. I was going to spray neem to fight the leaf minors, but held off until I figured out what the catapillar was. I guess I’ll hold off. I would love to see the butterflies. Neem would hurt them I suppose.
Insecticides generally do not distinguish between insects you want to keep and those you want to eradicate.
Letter 13 – Orange Dog
Subject: What the heck is this bug with a forked tongue?
Location: Culver City, California
December 13, 2015 5:20 pm
we just discovered this bug that looks like a reptile/caterpillar with a brown/greenish body with white on it & an orange forked tongue that’s on our little baby orange tree?
Signature: Cyn & Tony
Dear Cyn & Tony,
This is the caterpillar of a Giant Swallowtail, commonly called an Orange Dog. Caterpillars feed on the leaves of citrus trees, but they are not known to cause significant damage to a healthy tree. The orange forked tongue you mentioned is a scent organ called the osmeterium that releases an odor that might help to deter predators. Adult Giant Swallowtails are the largest butterflies found in Los Angeles. This is a species native to the eastern portion of North America, but with the cultivation of citrus crops in the west, there has been a significant range expansion. The Giant Swallowtail was first reported in Southern California in the 1990s.
Letter 14 – Orange Dog
Geographic location of the bug: Anaheim, CA
Time: 09:33 PM EDT
Three of these on my lime tree.
How you want your letter signed: Nuck
This is an Orange Dog, the caterpillar of a Giant Swallowtail, a butterfly native to the southeastern states of North America. The cultivation of citrus trees in Florida provided a host plant that the caterpillars will eat, and the Giant Swallowtail expanded its range to follow citrus cultivation, eventually reaching Southern California in the late 1990s. It is now well established in California. You may lose some leaves, but that is a small price to pay for the joy of seeing the magnificent Giant Swallowtails gliding gracefully around your yard.
Thanks. I love seeing the swallowtail. Exciting. Do the caterpillars have a predator?
While they don’t have a specific predator, we imagine they can become prey to birds, which is why they have evolved to resemble bird droppings as a form of protective mimicry.
Letter 15 – Orange Dog
Geographic location of the bug: Southern California, U.S.A
Time: 04:23 PM EDT
Hi! So I was just watering my lemon tree when I found this little weirdo hanging out. He’s 2 inches long and is a very thick boi. He seems to have only eaten 3ish leaves, so I think a bird dropped him or something. He was moving a bit when I found him, but he’s been completely still for the past 10 minutes. There are also these clear dot things I can’t tell if they’re eggs or not.
How you want your letter signed: With a signature
This is the caterpillar of a Giant Swallowtail, commonly called an Orange Dog because they feed on the leaves or orange and other citrus trees. The do not do enough damage to be considered a problem.
Letter 16 – Orange Dog
Subject: What is this?
Geographic location of the bug: Cypress, CA
Time: 04:31 PM EDT
Your letter to the bugman: This is currently on my lime tree and not moving. I thought it was a butterfly but the head looks like a lizard or snake.
How you want your letter signed: Rita
That’s ok! I found it! It’s a skull caterpillar! A Very cool bug indeed.
I love that you get so many photos of weird bugs that you cannot answer them all.
We are not certain where you found the name “Skull Caterpillar” but we do know that Orange Dog is a commonly used name for the caterpillar of the Giant Swallowtail. The markings on the Orange Dog, which feeds on the leaves of orange trees and other members of the citrus family, are thought to mimic bird dropping for protection.
Very interesting, thank you:)
I got the term skull caterpillar from a google search.
Letter 17 – Orange Dog
Geographic location of the bug: St. Augustine FL
Time: 08:33 PM EDT
Your letter to the bugman: Can you tell us what this is before we leave the state? Have lived in Florida for 17 years and have seen some strange bugs but this one takes the cake.
How you want your letter signed: Dennis
This is the Caterpillar of a Giant Swallowtail, commonly called an Orange Dog because they feed on the leaves of orange trees and other citrus.
Letter 18 – Orange Dog
Subject: What is this
Geographic location of the bug: Mobile, AL
Time: 07:34 PM EDT
Your letter to the bugman: Any idea what this is? Found on a lemon tree
How you want your letter signed: Laura
This is the Caterpillar of a Giant Swallowtail, commonly called an Orange Dog. It will eat some leaves, but it will not negatively affect the health of your tree. Unless there are hundreds of them or the tree is very very small, the tree can stand to lose a few leaves.
Letter 19 – Orange Dog
Subject: Never seen this before
Geographic location of the bug: Mississippi
Time: 04:00 PM EDT
Your letter to the bugman: Hello I was just writing to you because I was curious as to what this big is never seen it before and can’t find it online.
How you want your letter signed: Candace
Letter 20 – Orange Dog
Subject: Orange Dog
Geographic location of the bug: Francestown, NH
Time: 02:25 PM EDT
Your letter to the bugman: This is in reference to my 2012 post of a Giant Swallowtail Butterfly here: https://www.whatsthatbug.com/2
After 7 years finally noticed half a dozen or so on a Gas plant(Dictamnus albus).
How you want your letter signed: alf
Thanks so much for providing documentation of Orange Dogs in your New Hampshire garden seven years after first seeing an adult Giant Swallowtail, a species reported in Vermont on BugGuide, but not in New Hampshire. According to the Missouri Botanical Garden site, Gas Plant is in the citrus family Rutacea, which is consistent with BugGuide information on larval food plants.