Roots, Shoots, Fruits & Flowers: Managing Spiders, Armyworms, & Walnut Caterpillars (Again)


Black & yellow garden spider. Photo:

Managing Spiders

Nicole asked about controlling spiders at her home, “I have a question for you. Is there anything I can use to keep spiders away outside the house? More so around plants and bushes.”

Kalli Zammit and Rene Schmidt (retired), Extension Agents in St. Charles Parish, made these recommendations in an article, “pre-mixed and ready to use ‘Home Defense’ insecticides that contain bifenthrin, cyfluthrin, permethrin, or tetramethrin are readily available for the do-it-yourself consumer and are effective in controlling spiders in and outside the home. Spray applications should be made to corners and other dark areas of the house where spiders tend to hide and breed. Outside the home, spray applications should be directed under the eaves of the roof, along the base of the foundation, behind shutters and around doors and windows. Always make sure when purchasing an insecticide for indoor application that the label denotes ‘safe for indoor use.’

As all spiders have venom, many are incapable of piercing human skin. For that reason, most spiders found in Louisiana are harmless. The exception would be the black widow, brown widow, and brown recluse spiders. If by chance an encounter with a spider results in a bite, the American Red Cross recommends applying an antiseptic around the bite, including an ice pack to the affected area, and promptly consulting a medical physician.”


Armyworm pupae. Photo: Dr. Ron Strahan, LSU AgCenter.


An armyworm with an inverted "V" on its head. Photo: David Sexton, LSU AgCenter.


Dr. Ron Strahan, the AgCenter’s Turf Specialist, shared a note with extension agents that may be helpful to homeowners, “You may be receiving calls from clientele about turfgrass that just seemed to ‘die’ overnight. Likely, it is a non-fatal outbreak of armyworms that are heavily feeding on turf right now, particularly bermudagrass. Quick inspection of the site will likely confirm the presence of the several larvae feeding on the blades of the turfgrass (see attached pictures). Armyworms are daytime feeders so they should be easy to spot.

Tell clientele to treat with an insecticide ASAP to minimize damage. Multiple insecticide applications may be necessary with a heavy outbreak like this. Established turfgrass should recover quickly with good growing conditions. Fertilizing the damaged turf can speed up recovery. “

Some of the pesticides for treating armyworms include:

  • Bayer Advance Complete Insect Killer for Soil & Turf™
  • Bug-B-Gone™
  • Deltaguard™
  • Talstar™
  • Spinosad
  • Thuricide™
  • Sevin™


An egg mass of a walnut caterpillar attached to an old pecan leaf. Some eggs have already hatched out. Photo: Aaron Theall, DeRidder, LA

72_fig_5_early_stage_WC_Aaron_ThealljpgThese small walnut caterpillars are in the 2nd or 3rd growth stage. Photo: Aaron Theall.

Walnut Caterpillars

About five years ago, homeowners in southwest and central Louisiana were struggling with walnut caterpillars (WC) defoliating large pecans trees and leaving messy WC droppings. During the last two years, WC infestations seemed to be over. However, During the weekend of Independence Day, AHA observed light defoliation in his walnut and pecan trees by WC. Aaron in DeRidder sent some pictures of his WC attack.

AHA responded to Aaron’s email and recommended a possible treatment, “I have used Martin’s Dominion™ insecticide as a soil drench to treat my own trees. I mixed the drench in a bucket and poured the insecticidal mixture in a band around base of the tree. I used a soil drench because I did not have the means to spray aloft.

I think I had 50 percent control which was better than 100 percent defoliation. This insecticidal drench seemed effective on the lower canopy but not at the top of the tree. A treatment now may help with another round of caterpillars later this summer.”

“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.”

7/12/2021 1:41:58 PM
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