Lantana and Verbena How to Combat Insect and Mite Pests

E-195 2/05 LLantanaantana and VVerbenaerbena How to Combat Insect and Mite Pests Dale Mott and Michael E. Merchant* antana and verbena are perennial ornamental plants found in many Texas landscapes. These plants are known for their drought tolerance, cold hardiness and colorful flowers that generally bloom from March through October. LBecause of these attributes, lantana and verbena are very popular in residential and commercial landscapes and xeriscapes. They perform well in full sun and bloom in an assortment of colors. At first these plants appear to be problem-free Although lantana and verbena can survive most perennials that you can plant, water until estab- pests, you may need to intervene if the plant is lished, and then leave alone. However, there are attacked heavily. Intervention can help manage the several insect and mite pests that attack lantana and injury and stimulate the plant to continue blooming verbena. In most situations, their damage is minimal on its regular cycle. and goes unnoticed. The problem is recognized Most of the insect and mite pests that affect lan- when infestations become severe, and often the tana and verbena are similar. They usually suck sap cause of the problem remains a mystery. from the plant tissue (phloem) using mouthparts *Extension Agent—Integrated Pest Management and Professor that are adapted for piercing and sucking. As a and Extension Urban Entomologist, The Texas A&M result, the plant is injured, which reduces its vigor University System as well as the quality and number of blooms. Some insects—including aphids, whiteflies and mealybugs—also excrete a sweet, sticky material Lacebugs called honeydew, which drips down on the plant. Probably the most com- The honeydew accumulates on the leaves and stem mon insect pests found on of the plant and on whatever is nearby. Sooty mold, lantana are lacebugs. a black fungus, often grows on the honeydew, Populations of this pest resulting in the sidewalk or the side of the house Lacebugs generally do not build up being stained black. This problem is especially until temperatures climb to near 90 degrees F. noticeable on limestone (white rock) houses. Lacebugs are broad, flattened, rectangular and 1 1 You can prevent most pest problems by adopting small, about ⁄8 to ⁄4 inch long. Their bodies are usu- integrated pest management (IPM) practices. The ally brown to black. Their wings are partially trans- first step in an IPM program is identification. Once parent and gauze- or lace-like in appearance. An you identify the pest, you can then implement con- immature lacebug is blackish and wingless, with trol measures that are most effective, least expen- many small spines projecting from its body. sive and least harmful to the environment. The adult lacebug deposits its eggs on the underside of a leaf along the midrib, then secretes a Aphids brownish substance over the eggs to secure them to the leaf. When the leaves become heavily infested, Several species of aphids these dark, varnish- or molasses-like spots are very feed on lantana. Aphids noticeable. are small, soft-bodied 1 1 Damage on the top side of the leaf appears as insects about ⁄25 to ⁄8 inch white, brown or yellow specks caused by the insects long with relatively short Aphid feeding on the underside. Heavily infested leaves legs and antennae. You can turn yellow and die from the tips toward the base usually recognize aphids by their slow, deliberate and drop off prematurely. movement and the presence of cornicles or “tail pipes” on the apex (tip or top) of the abdomen. They can be winged or wingless. Their color varies from black to green, yellow or pink, depending on the Mealybugs species and the host plant. Mealybugs are closely Although some aphids lay eggs, most give birth to related to many of the live young that mature in as few as 7 days. Because scale insects that attack they mature so quickly, aphids can quickly build up many different types of plants. The name mealy- to high numbers in a relatively short period. Mealybugs bug is derived from the Aphids generally live in groups on buds, on the mealy or waxy secretions that cover the body of this undersides of leaves or in the plants’ terminal (end) insect. growing points. They suck sap from the plant and excrete honeydew, which you can see accumulating Mealybugs are soft-bodied insects that grow to 1 on leaves and stems of the lantana. Sooty mold ⁄4 inch long. They are found at rest or crawling often grows on the honeydew, making the plant slowly on stems or along veins on the undersides of unattractive and hampering its growth by reducing leaves. Their eggs are laid in clusters enclosed in photosynthesis. white, waxy, cottony material. Plants heavily infested with aphids appear wilted. Damage by mealybugs is similar to that caused by Some aphid species cause leaves to yellow or drop aphids. It is caused by sucking of plant sap, which from the plant; other species stunt and curl young stunts or kills the plant. Also, black sooty mold leaves (also see Extension publication B-6047, grows on the honeydew excreted by the mealybugs. Aphids in Texas Landscapes). 2 tations cause the leaves to turn yellow, gray or Whiteflies brownish and eventually drop off (see also Adult whiteflies are Extension publication L-1244, Destructive Mites in small, white, soft-bodied the Home Garden). insects. They are only 1 about ⁄16 inch long and Whitefly adult and nymphs have four wings. Weak Pest management fliers, they resemble tiny snowflakes fluttering Most populations of insect and mite pests are reg- about a plant. The wings and body are covered with ulated by naturally occurring beneficial insects, also a fine, white, powdery wax. known as beneficials. Some of these beneficials The immature stage is found on the underside of include immature and adult lady beetles, lacewing leaves. It is flat, oval in outline and slightly smaller nymphs, spiders and various tiny parasitic wasps. than a pinhead. Immature lacebugs are light green However, these beneficials may take longer to con- to whitish and are somewhat translucent. trol pests naturally than you’d like. In the mean- time, the plants are damaged and become stressed. Both immature and adult forms feed on lantana and verbena, leaving yellow spots on the leaves. To manage the pest population more quickly, you Heavy infestations can cause defoliation. Much like may employ a mechanical control method such as a aphids and mealybugs, whiteflies secrete honeydew, “water wand” sprayer or chemical control methods causing plants to be covered with the sticky sub- such as an insecticide. Many products are available stance (see also Extension publication L-1299, to control pests in residential and commercial land- Whiteflies). scapes; examples are provided in Table 1. You may also use other products with labels that cover lantana in general categories such as “ornamental Spider mites plants” or “flowering plants.” One of the most com- It is important to become familiar with a pesticide mon pests attacking orna- before using it. Always read and follow the pesticide mental plants is the spider label instructions. Be sure to use proper equipment mite, commonly referred and the rates of the product that are specified on to as a group as “mites.” the label. They are not insects, but Other protective measures include proper cultural are more closely related to practices such as watering and adding compost and spiders and ticks. Adult mulch. These practices will help keep the plants mites, spiders and ticks healthy and more tolerant of pests. In addition, have eight legs. Mature Spider mites proper soil fertility is also important to keep lantana mites are usually less than and verbena actively blooming throughout the sea- 1 ⁄50 inch long and generally are found on the under- son. But over-applying nitrogen can actually con- sides of leaves. tribute to plants being more attractive to the pierc- Mite infestations often go undetected until the ing-sucking insects previously mentioned. plants are damaged severely. Mite populations tend to Before adding more plants, make sure that the peak during the hottest, driest time of the year, gen- soil is good, well-drained and in an area that erally between July and mid-September. Mites can receives at least 8 hours of full sun per day. South easily be seen by shaking the foliage over a white and west exposures are perfect. Incorporating up to sheet of paper and observing any mites present. 4 inches of organic matter, such as compost and a 2- The undersides of infested leaves usually have to 4-inch layer of mulch, should be a standard prac- fine, silken webbing spun across them. Among the tice when adding new plants to a landscape. live mites, there may be cast skins, which leave a Also, to encourage constant blooming and a grayish residue on the leaf’s underside. neater appearance, be sure to lightly trim the tips of Damage from light infestations appears as yellow the plant occasionally. or gray stippled patterns on the leaves. Heavy infes- 3 Insecticides and Miticides for Pests of Lantana and Verbena Table 1. Examples of insecticides and miticides registered for use on insect and mite pests of lantana and/or verbena, 2005.* Generic or Active Pest(s) Labeled for Use Against: Ingredient Trade Name(s) Aphid Lacebug Mealybug Whitefly Spider Mite abamectin** Avid 0.15 EC ✓ acephate Orthene Turf, Tree & Ornamental Spray, WSP ✓✓ azadirachtin Safer Brand BioNEEM Multipurpose Concentrate Insecticide & Repellant ✓✓✓✓ Beauveria bassiana Naturalis-O ✓✓✓✓ ✓ carbaryl Chipco

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