Armyworm damage to a tomato.
Just when I thought we had vegetable protection handled with all of the cages we rebuilt last week, I found my basil leaves riddled with holes with barely any leaf surface left. As I looked more closely, I discovered caterpillars, mostly on the undersides of the leaves. They were about ½ inch in length. The basil plant is decimated. If I want fresh basil, I will have to plant more. I will leave the old plant as a trap crop for the next round of worms. I think they ate all my carrots too.
However, to add insult to injury, now that there is such little leaf surface left, the caterpillars moved on and are eating the tomato leaves and the new fruits. Yeesh! I did not realize that caterpillars other than the tomato hornworm ate tomato leaves. Every day in a garden is a learning experience.
I picked as many of the little pests off the basil as I could find, but just a couple of days later is when I found more on the tomato plants and they were an inch long. First, I threw them in the birdbath hoping the birds would eat them, but when I found them still floating there today, I realized that was not working. I started squishing them, but that is pretty gross. Finally, I flung them far into the yard thinking the birds might find them there.
I am a big fan of butterflies and many moths. To have these desirable creatures, I should welcome caterpillars too. Yet, since it is so hard for me to grow any vegetables or herbs successfully with the ground squirrels, it is quite discouraging when an insect pest eats up my few precious plants. What is next? Grasshoppers? Snails? Slugs?
I think the caterpillars are armyworms, which are called that because infestations can be quite large, and defoliation can happen quite quickly, as it did with my basil. One day it was fine, and the next ruined. According to Texas A&M University, these critters feed throughout the day but are most active in the early morning and late evening. That is when I need to go on caterpillar patrol. Unfortunately, there can be one to three generations per growing season from mid-July through September.
My management solution will remain hand-picking, squishing or bird feeding. I did catch a small toad and put it in the tomato/basil container. I’m hoping he stays and feasts on caterpillars. There are organic insecticides such as the bacteria Bacillus thuringiensis (Bt), pyrethrins and horticulture oils. I never advise using synthetic insecticides on vegetables. Don’t we grow our own to have pesticide-free produce?
JoAnne Skelly is Associate Professor & Extension Educator Emerita, University of Nevada Cooperative Extension. Email skellyj@unr.edu.