Hi Brenda,
The article that Zizzle cited about Brazil is talking about ordinary corn earworms, which are basically the same caterpillars as the cotton leafworm, and they're closely related to cotton bollworms and various other caterpillars that prosper in various ag crops. For controlling them in sweetcorn in a garden, a vegetable oil can be used, as described in articles such as
this: Unfortunately they're not so easy to control in other crops. Caterpillars are relatively difficult to kill, as insect pests go.
The safest control method (IMO) is the biological pesticide, Bacillus thuringiensis (Bt), but now that Monsanto has GMO'd the Bt trait into corn seed, a lot of anti's view it as somehow dangerous. (We've been eating the Bt toxin residue for hundreds of years, because it has always been produced naturally when the bacteria propagate on corn, but now that Monsanto has become a middleman in the process, Bt is suddenly a bad thing.)
Gardeners traditionally used carbaryl powder (Sevin Dust) for that purpose, and it still works well for killing all types of caterpillar pests. But carbaryl is not considered to be as safe these days, as it once was. Probably the biggest argument against it is the fact that it kills honeybees. So most gardeners probably eschew Sevin Dust these days.
That's a two-way street, though. I recently used Sevin Dust to wipe out a swarm of bees that had been coexisting peacefully for many years under an abandoned, upside down horse feed trough, in a no-longer-used corral near the farmyard here. Apparently, they had recently been infiltrated/cross-bred with Africanized (killer) bees, because beginning this spring, whenever I would fire up a lawnmower to mow the lawn, a few scouts would immediately come to check me out, and they wouldn't give up. They followed a behavior pattern that I had never noticed in bees before. Instead of just swarming around me, or landing on me, or stinging me, they kept tapping me on the back of my neck and head, over and over again, and they would follow me for a very long way away from the hive. Now bees are often cantankerous in cloudy or unsettled weather, so I just gave them the benefit of the doubt, and waited until after dark to mow the lawn.
Then one day, I started mowing after sundown (but before dark), and they pulled the same old stunt, except that instead of 1 or 2 of them, 3 or 4 of them followed me around, repeatedly tapping me on the back of the head and neck, and then one of them stung me on an ear. That did it for me. After I finally got away from them, I waited until after dark, and then I mowed the lawn, but as I was mowing, I was busy trying to decide whether to have them removed, or just destroy them.
When I turned on the tv that night, the local news was on, and they were talking about someone who had been killed by a swarm of bees, in a small community roughly 25 or 30 miles away. I don't often watch the news on tv, but that captured my attention, especially when they interviewed a beekeeper who happened to mention that killer bees have a characteristic habit of "marking" their victims by repeatedly tapping them on the back of their head and neck, so that when the rest of the swarm arrive, they will know exactly where to go.
The next morning, I bought a couple of containers of Sevin Dust, and for 3 nights in a row, I sprinkled it liberally on and around the entrances that they were using to get under that trough. After that, I saw no more evidence that any survived.
During my lifetime, I've had several close scrapes with death, ranging from rolling a loaded grain truck after two tires blew out at the same time on the same side, to waking up one morning with massive, uncontrollable internal bleeding. But I believe that the realization that I had been living that close to a potential killer bee attack wins the award for the scariest close call that I've ever had. I believe that what saved my hide was the fact that I knew exactly where the hive/swarm was located, and I stayed away from there. Most people who are killed by killer bees don't realize the swarm is there, and they get too close before it's too late.
Sorry for the side track, but to get back on topic, the "worms" that I was referring to are the Mexican corn rootworm. In the High Plains, you may well have an overlap of all species of corn rootworms. At the very least, you should have western, southern, and Mexican corn rootworms. I'm not sure if the northern corn rootworms are found that far south, though. That doesn't mean that the Mexican corn rootworms may be as big a problem there as they are here. Down here, the ground rarely freezes during the winter, so that may be one of the reasons why they are so successful at overwintering. It gets a lot colder up there on the high plains where you are.
Since the southern corn rootworm adult is also known as the spotted cucumber beetle, you should be familiar with them. Like the adults of other corn rootworm species, they like to hang out on cucurbits (cucumbers, squash, gourds, etc.). Down here, the adults are usually the most abundant around late May to early June, (when the corn is silking), so that's the time to look for them, because the adults feed on cornsilk. Corn probably silks later up there though, so you may need to adjust the time frame accordingly. If you go to the site at the link below, and scroll down the page, you can see pictures of all of the various adult stages:
https://www.pioneer.com/home/site/us/ag ... -rootworm/
If you have high populations, you will see a lot of adults. If you don't see many adults, you probably don't have much of a problem. The southern corn rootworms have been here forever, but they rarely cause any major damage, so seeing a bunch of spotted cucumber beetles is usually nothing to get excited about (unless you're a cucumber. LOL). What bothers me is that we don't normally notice any Mexican corn rootworm adults, even though population levels are very high around here, so I'm not sure if we're just looking at the wrong times, or if they tend to lay low, or something else is going on.
The adults can also be controlled by carbaryl, or by pyrethrin sprays, but there are few organic control methods that will work against a heavy infestation.
Tex
