Tobacco budworms, also known as Heliothis virescens, are a common pest that can damage various plants such as petunias, geraniums, and nicotiana. These caterpillars are typically seen during late summer, causing round or irregular holes in flower buds. It’s important for you to be aware of this pest and how it can affect your garden, so let’s dive in and learn more about them.
The adult stage of the tobacco budworm is a moth with a wingspan of around 1 1/2 inches. These moths have light green wings with gray or brown overtones and a few cream-colored bands. You’ll likely spot them during early evening since that’s when they are most active. Female moths lay eggs on plant buds or leaves, leading to the development of the damaging caterpillars.
Tobacco budworm caterpillars can show quite a variety in their overall color, ranging from light yellow-green to dark green or brown as they mature. Their feeding behavior can lead to different types of damage, with Type 1 Damage being the most common, which doesn’t typically result in a significant yield loss. However, Type 2 Damage can have more of an economic impact, so it’s crucial to monitor and manage these pests in your garden.
Taxonomy and Identification
Lifecycle and Stages
The Tobacco Budworm, scientifically known as Heliothis virescens, is a species of caterpillar that can cause damage to plants like petunias, geraniums, and nicotiana. They have a complete life cycle involving four stages: eggs, larvae (caterpillars), pupae, and adult moths.
As the eggs hatch, caterpillars emerge and feed on various plants, going through several instars – or stages of development. After reaching full size, the caterpillar enters the pupal stage, where it transforms into an adult moth.
Tobacco budworm caterpillars can vary in color, ranging from dark forms to red, green, or light brown. One distinguishing feature is their brown head capsule. As the caterpillar grows, the size of the head capsule also increases, which can help determine its stage of development.
Adult moths have a distinct look as well. Their wings have shades of light green with gray or brown overtones, along with some wavy, cream-colored bands. Moths are most active during early evenings.
Heliothis virescens caterpillars can display various features, such as:
- A brown head capsule
- A varying body color (dark, red, green, or light brown)
- A patterned dorsal and lateral surface
- A gray or brown head capsule in adults
- Cream-colored bands on adult moth wings
Knowing the physical appearance and lifecycle of the Tobacco Budworm can help you identify them when scouting in your garden, ensuring that you can take the necessary steps to protect your plants from damage.
Tobacco Budworm’s Environment
Preferred Host Plants
Tobacco budworms are primarily attracted to plants such as geraniums, petunias, and roses. These caterpillars can cause damage by creating irregular or round holes in flower buds. Besides these plants, they can also infest:
Habitat and Distribution
Tobacco budworms are commonly found across the United States and have a presence in several crops. Their generations per year vary depending on location. For example, in North Carolina, there are typically four generations per year. These pests overwinter as pupae in the soil and thrive in warm climates. They can be found in:
- Vegetable gardens
- Ornamental landscapes
It’s crucial for you to monitor your plants for signs of tobacco budworm infestation, especially during the late summer when they are most active. By understanding their preferred host plants and habitats, you can take preventative measures to protect your plants and maintain a healthy environment for them.
Signs and Symptoms of Infestation
Damages Caused by the Budworm
Tobacco budworms, also known as geranium budworms, can cause significant damage to plants like petunias, geraniums, and nicotiana. If you’re in an area like Colorado, it’s essential to be aware of the potential harm these pests can cause. Some of the damages include:
- Holes in flower buds: Tobacco budworms tend to create irregular or round holes in flower buds1. This damage ultimately affects the development of blossoms.
- Terminal growth damage: The caterpillars can also attack the terminal growth areas of a plant, leading to stunted development.
Physical Markers of Presence
Identifying tobacco budworm infestation requires observing physical markers:
- Colors: The larvae can have variable colors, ranging from red, brown to green2.
- Frass: You may notice frass (caterpillar droppings) around your plants that are infested with tobacco budworms.
- Spherical eggs: These pests lay eggs on buds and leaves2. The eggs are typically spherical with a flattened base.
In case you need to manage a tobacco budworm infestation, it is worth noting that parasites like Cardiochiles nigriceps can be used as biological control agents3. By understanding the signs and symptoms of infestation, you can take timely action to protect your plants from the adverse effects of tobacco budworms.
Prevention and Control Measures
Biological Control Methods
To protect your plants from the tobacco budworm, consider using biological control methods. One effective method is introducing Bacillus thuringiensis (Bt), a natural soil bacteria, to target the larvae. Bt is safe for beneficial insects, like bees.
Another biological control method involves encouraging the presence of predators and parasites in your garden. Some examples are:
- Predatory insects, such as ladybugs, lacewings, and spiders
- Parasitic wasps that attack and lay eggs inside budworm larvae
Maintaining a diverse and healthy garden with a variety of plants can attract these beneficial organisms.
Chemical Control Methods
If biological control methods are not sufficient, you could turn to chemical control methods. Before applying any insecticides, make sure to scout for budworms and identify the level of infestation.
Two common garden insecticides are:
Spinosad: Derived from a naturally occurring soil bacterium and is low in toxicity to beneficial insects like bees. Follow label directions carefully to protect your garden.
Pyrethroid insecticides: These synthetic pesticides target a variety of pests, including tobacco budworms. However, they can be toxic to beneficial insects, so use them judiciously.
|Toxicity to Bees
|Conserve SC, Entrust
|Many insects, including budworms
Always remember to follow the insecticide’s label directions for proper usage and application rates. And keep in mind, using insecticides may not be the best long-term solution, as budworms can develop resistance to them.
In addition to these methods, you can also remove weeds from your garden, as they can harbor pests, and handpick tobacco budworms from your plants to reduce the population.
Tobacco budworms are a common garden pest that can damage various plants, including petunias, geraniums, and nicotiana1. Adult moths lay eggs on buds or leaves, and caterpillars feed on plants’ foliage. The life cycle from egg to adult can last about 21 to 25 days, with four generations per year3.
Here are some essential points about tobacco budworms:
- Their appearance can vary: caterpillars range from yellowish-green to pale green, with some having a pinkish hue4.
- Adult moths have a wingspan of about 1 1/2 inches and are light green with gray or brown overtones4.
- Their front wings display three slanted, dark bands and hind wings have cream-colored bands5.
To effectively scout for tobacco budworms, look for irregular or round holes in flower buds1 and caterpillar droppings on leaves.
Proper identification is crucial in controlling tobacco budworms. They can be confused with corn earworms (Helicoverpa zea), which have a broader crop host range3. Here’s a comparison table for ease of identification:
|Adult moth color
|Light green with gray/brown overtones
|Greenish or brownish gray
|Front wing bands
|Three slanted, dark bands
|Dark, irregular bands
|Hind wing color
To prevent infestations, you can use Bacillus thuringiensis (Bt), a natural soil-dwelling bacterium that’s effective against caterpillars4. Regularly check plants for signs of damage, monitor temperature, and remove larvae when found. Taking preventive steps can ensure the health of your garden and minimize the impact of tobacco budworms on agriculture.
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 – Tobacco Budworm eats Cannabis sprout
Geographic location of the bug: Mount Washington, Los Angeles, California
Time: 05:46 PM PDT
Your letter to the bugman: I found a bud worm on a sprout indoors under lights????
How you want your letter signed: Mel Frank
Thanks so much for your submission of a Tobacco Budworm caterpillar, Chloridea virescens. We are honored to get this important documentation from such a distinguished expert. BugGuide also has documentation of a Tobacco Budworms feeding on marijuana.
Letter 2 – Tobacco Budworm on Medical Marijuana
Subject: Please don’t be a Budworm
Geographic location of the bug: Mount Washington, Los Angeles, CA
Time: 05:56 PM EDT
Today while inspecting my medical marijuana plants, I discovered this caterpillar. I also discovered some brown buds. Is this a dreaded Budworm?
How you want your letter signed: Constant Gardener
Dear Constant Gardener,
This does appear to be a Tobacco Budworm, Heliothis virescens. According to Rollitup: “The tobacco budworm varies greatly in appearance so it can easily be confused with other species. Making an accurate ID of your attacker can be important because some species have built up resistances to certain treatments. Luckily for us growers, if you find a caterpillar on your plants you can be 99% sure its a tobacco budworm. If you live in Africa, Europe, New Zealand, Australia or Asia its going to be the species Helicoverpa armigera. If you live anywhere else its going to be the species Heliothis virescens. The distinction between these two species is not important however since they can both be treated using the same methods. Most people find the larval form (caterpillar) on their plants so I won’t spend much time describing the adult moth. The caterpillars are initially pale green and often have black dots covering their body. Thin dark lines run down the length of the abdomen and tend to be darker around the second and third segments. As the larva ages (progresses in instars) the black dots may develop a red border around them. The abdomen is also covered with numerous microspines that give the caterpillar a rough feel. The head capsule is nearly always a light brown color. Again I wouldn’t worry too much if this description doesn’t completely match up with the caterpillar you find. There is great phenotypic variation in the tobacco budworm so there can be different colors and designs.” According to Featured Creatures: “Tobacco budworm is principally a field crop pest, attacking such crops as alfalfa, clover, cotton, flax, soybean, and tobacco. However, it sometimes attacks such vegetables as cabbage, cantaloupe, lettuce, pea, pepper, pigeon pea, squash, and tomato, especially when cotton or other favored crops are abundant. Tobacco budworm is a common pest of geranium and other flower crops such as ageratum, bird of paradise, chrysanthemum, gardenia, geranium, petunia, mallow, marigold, petunia, snapdragon, strawflower, verbena, and zinnia.” No mention is made of Cannabis being a host plant. When we searched that BugGuide, we found an image very similar to your own, and according to BugGuide the food plants include “Cotton, tobacco, roses, ground cherries, soybean, and many others.”
Letter 3 – Tobacco Budworm? or some other caterpillar???
September 22, 2009
Well, the yard has exploded with moths, butterflies and caterpillars – counted 11 black swallowtail cats on the dill and parsley, with countless eggs still to hatch, and found 2 empty chrysallises on the porch rail and landscape timbers in the yard. The snaps are full of Buckeye caterpillars which go nicely with the Buckeye flag hanging from the porch (it’s football!! Go Bucks!!) While inspecting the dill, I found this pink striped caterpillar on the Russian sage that’s planted next to the dill (and under the Ohio State flag). It’s been at least 3 days of searching but I think this comes close to BugGuide’s Tobacco Budworm – the description says it tends to take on the color of the plant it’s eating. It was also getting close to sunset, so the light and the flowers on the Russian sage really helped hide this one. Please feel free to correct the ID – I think we’ve looked at over 8 million pictures of pink caterpillars since Saturday night. Thanks!
Newport News, VA (southeastern VA)
We love the enthusiasm in the tone of your letter. This looks like it may be a Tobacco Budworm, Chloridea virescens, but we are not certain. We will post your letter and image and link to the BugGuide page on the species in the hopes that an expert can provide some input.
Thanks so much! I’d actually already been to your site before going to my email and was delighted to see the pictures already there. You all are terrific and do such a good job!
My daughter is an elementary school art teacher and brought her school’s science teacher over yesterday to “harvest” some caterpillars from the yard. They took 3 or 4 black swallowtail caterpillars, then went to the local garden center and picked up a few dill plants and are hoping to be able to follow the caterpillar to butterfly saga all the way through. They also found a fuzzy tan caterpillar out on the green cones – the guy looks like he needs a serious day with a hairstylist – that we’re working on identifying. And this morning, the snaps were covered with at least a dozen Common Buckeye caterpillars. It’s all just a great reward for planting for butterflies!
Thanks again for your great site and all the good work you do.
Letter 4 – Tobacco Hornworm on Nightshade
what is this bug?
I was weeding my garden today and came across this huge guy! What is it and is it a moth or a butterfly? My kids are so curious! Thank you 🙂
Just today, we received the following letter that set us straight. Seems we haven’t really distinguished between two larvae, both commonly found on tomato plants, that Grandma always called “Tomato Bugs.” Your caterpillar is a Tobacco Hornworm.
the difference between Tobacco Hornworms and Tomato Hornworms
(07/28/2006)Tobacco and Tomato Hornworms
You have Manduca sexta and Manduca quinquemaculata both identified as tomato hornworms. I think sexta is the tobacco hornworm; it has seven stripes that are diagonal when viewed from the side, and the “horn” is usually red. Quinquemaculata, the tomato hornworm, has eight markings which, when viewed from the side, look like chevrons pointing towards the head, and the horn is usually black. The pictures on your site are of the tobacco hornworm, which seems to be far more common in gardens; people often ID them as the tomato hornworm because they are eating their tomato plants. The adult tomato hornworm is the 5-spotted hawk moth and the adult tobacco hornworm is the Carolina sphinx moth. I have a tobacco hornworm the size of my thumb in a jar, and its poops are big as rabbits’.
(08/02/2006) Hi bugman,
I am a professional horticulturist and love your wonderful website! I wanted to let Kelly Dean know that the plant her tobacco hornworm is on in the picture is clearly a deadly nightshade. This beautiful vining plant in the tobacco/tomato family has pretty purple flowers and bright red berries which appeal to children. It is a very poisonous plant! Especially since she has kids in the garden, I would recommend she move the hornworm to a tomato or pepper plant for her kids to study, and get rid of that deadly nightshade. Better safe than sorry! Thanks,
Bucks County, PA