Control Eastern Leaf-footed Bugs on Thistles
By George Giltner, Adv. Master Gardener
Springtime is when bug control begins. Already as temperatures have risen into the high seventies, the Eastern Leaf-footed bug, Leptoglossus phyllopus, has arisen from winter hiding places like in firewood, plant debris, around warm hay piles, etc. Its mid-body white stripe and the broad leaf-like back legs easily identify this common pest.
Thistles (Cirsium spp.) are their principal host plant while they are tender and succulent. Therefore take advantage of this time to spray for control before populations expand and infest summer fruits, nuts, ornamentals, and vegetables. Around organic gardens, OMRI-listed, “End All, Organic Insecticide” by Safer is a good choice. It contains a mixture of neem oil, potassium soap, and organic pyrethrins that do not harm beneficial insects when used as directed.
Other more harmful insecticides including pyrethroids, carbamates, and organophosphates can currently be used, but carefully read all safety precautions and follow all instructions. Author Janie F. Shelton, warns pregnant women to avoid contact with these agricultural chemicals in a NIH article, Neurodevelopmental Disorders and Prenatal Residential Proximity to Agricultural Pesticides: The Charge Study (www.ehp.niehs.nih.gov/1307044/).
Cultural controls are to mow areas that contain thistle and other food sources. Plowing under weeds and destroying winter left over crop debris will also reduce bug food supplies and hidden nymphs.
There are few biological controls for the eastern leaf-footed bug. Two of these are tachinid flies, Trichopoda pennipes and T. plumipes. Birds avoid these cousins of stink bugs, due to their mimicry of wasps or their foul odors.
Mechanical control is by hand picking in the garden or vacuuming. Cool mornings in spring slow the bugs down enough for easy captures, however in warm afternoons, this process is more challenging. The nymphs are orange to a golden brown with black legs. Since they are wingless and have group behavior, capturing is easy. The brown eggs form a broken cylinder that is laid along the stem or a leaf midrib. You will have 5-7 days to peel these off before they hatch.
Leptoglossus will move to pecan, citrus fruits, blackberries, blueberries, apples, peaches, pears, plums, beans, peas, bell peppers, tomatoes, eggplants, corn, cucurbits, and other plants as the season progresses. The bug’s sucking mouth-parts transmit disease, cause discoloration, pitting, plant wilting, and even plant death in large numbers. Therefore early control on thistle weeds is more desirable than trying to control large numbers of locally grown leaf-footed bugs on produce crops later in the season.
George Giltner is a Master Gardener in Beauregard Parish. He is an MG instructor in entomology and organic gardening.