Roots, Shoots, Fruits & Flowers: Whiteflies, Assassin Bug, Oak Aphid, & Walkingstick Insect

Lori in Baton Rouge sent an email, “Please identify the culprit in the photo. I have assumed it is whitefly because of the color but I cannot see the critter well enough. I have found them on the foliage of both Louisiana and bearded iris and gladiolus foliage. I have sprayed them with neem oil and insecticidal soap. They fly up when the spray hits them. and there will be a visible improvement but then within a week it seems the infestation is just as heavy as before. How should I treat this problem?”

Dan Gill, retired horticulture specialist, wrote about treating whiteflies in ornamental plants, “Controlling whiteflies can be difficult, especially when the population levels get high. On ornamentals you can use Talstar®, malathion, acephate or dimethoate. Although oil sprays are not recommended for use in summer when daytime highs go above 85 degrees, highly refined paraffinic insecticidal oils, such as Bonide Year-Round Oil®, can be used now and are effective against whiteflies. Oils kill by suffocation and are an excellent low-toxicity insecticide. Spray in the early morning when temperatures are cooler. Check the label carefully for the safe and proper use of these pesticides as well as the list plants on which they may be used.”

Joe sent in a picture of an insect for identification. Victoria Bayless, Curator of the Louisiana State Arthropod Museum, helped with the identification, “This is an assassin bug (Family: Reduviidae) which is the common name for the entire family. This one is an adult, Zelus longipes, sometimes called the long-legged assassin bug.”

Blake Wilson and Rodrigo Diaz, both entomologist with the AgCenter, wrote a factsheet, The Assassin in the Garden, about assassin bugs and why they are beneficial, “Assassin bugs are true bugs (Hemiptera) in the family Reduviidae. They feed on a diverse variety of insects including flies, mosquitos, roaches, beetles, aphids, and caterpillars. While these insects will not attack humans or pets, their bright colors should serve as a warning. Painful bites can occur in self-defense if the insect is handled or if accidental contact is made during gardening activities. Bites are rare despite the common occurrence of these insects and the benefits of having them in a garden far outweigh the risks.”

Kevin Savioe, an Area Agent in Cameron Parish, asked, “Please identify [the] fuzzy growth on [the] oak leaves [in this picture].”Again, Ms. Bayless helped with this ID, “There is a wooly oak aphid (WOA) that I would put my money on… but best to find the creature under the wax…”

Anna Timmerman, an Area Horticulture Agent in St. Bernard Parish, wrote in a GNO Gardening newsletter about WOA treatments, “Contact insecticides that are sprayed on these guys may not work so well because of their protective wax coverings. Wooly aphid adults tend to just fly away when disturbed. Systemic insecticides are also not very reliable for control…. Furthermore, since many of the plants that they feed upon are also pollinator or host plants for butterflies and bees, they should be avoided. A stream of water from a hose can work to blast them away, as can washing the plants by hand with an insecticidal soap.”

Gyneth, a Master Gardener, and beekeeper in DeQuincy, sent a text image of an insect and wanted to know what is and if it harms honeybees. Again, Ms. Bayless helped with the name of this insect, “This is our most common stick insect, two-lined walkingstick.” This insect feeds on plants and is considered harmless to honeybees. Still, this insect deserves our respect because “it is capable of squirting a strong-smelling defensive spray that is painfully irritating to the eyes and mucous membranes.”

If you want to contact Roots, Shoots, Fruits, and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337.284.5188 or or .

“Before you buy or use an insecticide product, first read the label, and strictly follow label recommendations. Mention of trade names or commercial products in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”

“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”


Figure 1. White flies


Figure 2. Long Legged Assassin Bug


Figure 3. Wooly Oak Aphids


Figure 4. Walking Stick

7/29/2022 10:31:47 PM
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