Lantana plants are prone to a few very common pests no matter if they grow in a greenhouse or outdoors in a garden bed. Sap-suckers like Whitefly, Spider Mites, and Lace Bugs are much more of a nuisance than a danger to otherwise healthy and mature plants. The Caterpillars that are common pests for Lantana will generally be for beneficial pollinators like Painted Lady and Hairstreak butterflies and not the more damaging web spinning Caterpillars.
These butterflies and a few moth species use Lantana as a host plant to raise their caterpillars before pupating. Removing any damaged stems is enough to treat the plants until the season is over.
Whitefly
Greenhouse growers are more likely to have trouble with whitefly than outdoor gardeners. The closed-in space and high humidity are perfect breeding grounds for Whitefly, especially Trialeurodes vaporariorum, the Greenhouse Whitefly. Adults are sap-sucking insects that are able to fly only a short distance.
Infested plants will have yellow spotting on the undersides of leaves where feeding has taken place. Large outbreaks can cause early leaf drop on plants and because these are sap-sucking insects, large amounts of honeydew may be present on either the plants or surrounding surfaces.
Treating Whitefly On Lantana
Monitoring for levels of Whiteflies and other insects in the greenhouse is important to keep populations low. Hanging sticky yellow card traps near susceptible plants lets you know when levels are high enough to treat plants. Whiteflies also swarm away when plants are moved or brushed against. Moderate outbreaks can be treated with a blast of water from the hose or a horticultural soap spray applied until it runs off leaves.
Plants that are perennial or routinely attacked by Whiteflies may be better off disposed of to prevent infecting other plants. Prune out damaged plant material to prevent secondary infections from fungal or bacterial diseases.
Preventing Whitefly On Lantana
Wetting down greenhouse floors and walls helps to raise humidity levels during hot weather and support Whitefly natural predators such as lady beetles, and minute pirate bugs. Allow adequate space between potted plants for good air circulation and resist the urge to over-fertilize young plants with high-nitrogen fertilizers.
Using broad-spectrum pesticides affects good and bad insects equally and should only be used as a last resort for heavy infestations.Weed control in the garden or around the outside of a greenhouse helps to reduce host plants that could overwinter adult whitefly or their eggs.
Caterpillars
Various butterflies and moths not only feed on the nectar of Lantana but use it as a host plant for raising their caterpillars. Sphinx moths, painted ladies, and Hairstreak butterflies are just a few types that are commonly found in backyard gardens across North America. The damage to leaves can look quite severe. The leaf margins will be ragged with large holes also eaten from the center.
Small black or brown dots may be found on the top or bottom of the leaves which are frass from the caterpillars. Lantana is rarely the host to more destructive web-forming as they prefer mainly woody shrubs and trees to grow on. Damage from butterfly and moth caterpillars can be quickly outgrown early in the growing season.
Treating Caterpillars On Lantana
The easiest way to control caterpillars is to hand-pick them off when they are visible. Deposit them in a bucket of soapy water to kill them completely or relocate them a good distance away from the Lantana plant 1in hopes that they will still find a spot to pupate. Remove foliage that is distorted or rolled as they may be hiding caterpillars.
Preventing Caterpillars On Lantana
Preventing caterpillars from munching on your Lantana plant isn't always necessary as the damage caused is less than allowing the butterflies and moths to thrive in your garden as they can be very beneficial pollinators for other plants. Using targeted bacterial insecticides like Bacillus thuringiensis will help to control the larval stage of most insects including butterflies and moths.
Periodically removing damaged leaves and stems will help protect your Lantana from a secondary fungal infection. Attracting higher-level predators such as birds and small mammals into your garden can help control caterpillars as they feed themselves and their young.
Leafminers
The adult leafminer is a small black flying insect that lays its eggs in between layers of the Lantana leaf. When the eggs hatch the larval stage feeds on the insides of the leaves leaving random and crazy-looking patterns on both the front and back of the foliage. The larva eventually hatch and fall to the ground in search of another plant to feed on and lay another generation of eggs.
New generations can be produced as quickly as every two weeks during periods of warm weather and until the cooler weather of fall. Leaf-mining on lantana typically does no lasting damage. Growth may slow while the Leafminers feed, but after leaving the foliage normal growth resumes.
Treating Leafminers On Lantana
Picking off affected leaves is generally all of the treatment needed during an outbreak of leafminers. Small seedlings can be grown under cover (horticultural fabric or very fine insect screening) until they are large enough to tolerate feeding by the Leafminers.
Preventing Leafminers On Lantana
Growing healthy and regularly watered plants helps to keep Leafminers at bay. Removing spent foliage at the end of the growing season also helps to reduce the chance of any overwintering pests in the garden. Encouraging predatory beneficial insects in the garden is also a great way to control outbreaks of pests. Lacewings, Lady Beetles, Syrphid flies and predatory wasps are just a few of the beneficial insects a healthy garden attracts.
Lacebugs
Lacebugs may cause the most damage to lantana plants, especially in climates where it grows as a woody perennial. The small brown or black bugs have clear wings and feed on the bottom side of leaves. Lacebugs are highly active when temperatures are above 90F causing quick yellowing and browning of foliage and early leaf drop. The female lace bug lays masses of eggs on the underside of the foliage near the midrib and coats that whole area in a sticky molasses-like material to protect them.
Treating Lacebugs On Lantana
Light infestations can be waited out until the weather cools in late summer or early fall. In the meantime prune out any infected plant material and dispose of it in the trash. Contact insecticides such as horticultural soap sprays or oil sprays will kill off the adult stag on contact. Do not use a broad spectrum or systemic insecticide as they not only kill off all insects (including beneficial ones) but also weaken plants making them more susceptible to further outbreaks.
Preventing Lacebugs On Lantana
Good garden hygiene at the end of the growing season removes potential litter for overwintering insects. Plant Lantana in full sun where it also has excellent soil drainage to have healthy plants able to withstand insect attacks. Plants that are highly fertilized will have copious amounts of foliage and root systems that are not equipped to support the top growth. Foliage-feeding pests like lace bugs take advantage of this weakness and move in quickly, especially if high temperatures or issues with underwatering have stressed the plant.
Spider Mites
Spider mites occur in either a greenhouse or indoor growing setting or outdoors in the garden. Warm temperatures and very low humidity are the perfect breeding ground for Spider Mites. Indoor humidity levels below 40% in the wintertime are [particularly appealing for the mites. Plants overwintering as cuttings or houseplants should be carefully monitored throughout the Spider mites are sap-sucking insects that feed primarily on the foliage leaving areas of yellow or white stippling.
Over time large populations will weaken the plants, interfering with their everyday functions like photosynthesis and the movement of nutrients around the plant. Spider mites weave fuzzy webs in the leaf and stem joins to protect themselves and their eggs from predators. It is also typically the first visible sign that there is an infestation.
Treating Spider Mites On Lantana
Horticultural oil sprays are effective at treating Spider Mites although they should be used as a last-ditch effort. Broad-spectrum Insecticides tend to encourage larger outbreaks of mites due to them also killing off the beneficial predators that keep populations low. Encouraging and supporting beneficial predators like minute pirate bugs and lacewings efficiently balance the amount of pests in the garden or greenhouse environment.
Wetting down greenhouse walls and floors with water in hot days increases the humidity levels dramatically making it less hospitable for Spider mites who prefer extremely low humidity.
Preventing Spider Mites On Lantana
Keep plants well-watered during periods of hot and dry weather. Place watering cans filled with water in greenhouses to temporarily raise the humidity near plants. Regular washing off of plants during dry periods can also dislodge early spider mites discouraging an outbreak.
Common Lantana Pests Chart
| Pest | Identifying | Treating |
|---|---|---|
| Whitefly | Small white bugs that fly off the plant when disturbed or moved, yellowed foliage where they have fed, honeydew secretions | Grow plants in full sun, avoid overwatering, horticultural soap or oil spray, provide plenty of air circulation |
| Caterpillars | Ragged holes or margins of the leaves, whole leaves missing, distorted leaf growth | Hand-pick caterpillars, prune out heavily damaged plant material, and remove weeds from the garden that may be host plants for the insect's eggs. |
| Leafminers | Stippled leaves from adults feeding, trails twisting and turning visible between the layers of the leaf | Prune out affected leaves, the larval stage rarely causes damage to the health of the plant and is mainly cosmetic, avoid over or under-watering the plant. |
| Lacebugs | ⅛-¼ brown or black bug with almost clear wings, flowers not forming, yellowing top side of leaves that is the result of feeding on the bottom, clusters of eggs on the underside of the leaf covered in a brown sticky sap | Encourage natural predators such as lady beetles, lacewings, spiders, and parasitic wasps to keep populations in control, use a non-residual spray on large infestations such as soft soap spray or horticultural oils. Wait out the infestation until temperatures fall in late summer |
| Spider Mites | Small red dots on either side of the leaf are not easily visible without a hand lens. Yellow stippling on the leaf, white webbing when infestation is advanced | Minute pirate bugs and lacewings are natural predators, increasing the humidity with regular watering during periods of low humidity, horticultural soap spray |
Sources: “Lantana and Verbena: How to Combat Insect Mite Pests”, Gillespie County Extension. www.gillespie.agrilife.org