MOTH madness found exciting by entomologist

Monday, May 28th 2001, 12:00 am
By: News On 6

(NORMAN) - Ken Hobson can't take his eyes off his front porch. As soon as the sun goes down, the entomologist flips on his porch light and curiously observes what he calls a fascinating phenomenon.

It's a phenomenon most of us consider a little irritating. Hobson, however, can't get enough of this moth madness.

``They're exciting to see. It makes you conscious of the natural world,'' Hobson said. ``I love to look at them in the evening, close up. If you hold them up to the light, you see that their eyes shine bright red or orange. It's beautiful.''

Hobson, curator of invertebrates at the Sam Noble Oklahoma Museum of Natural History, said the larger-than-average moth population is a result of a mild, dry winter and cool, wet spring. Although Oklahoma had a pretty harsh winter, he said, the critters were most likely blown here in broods by southerly winds from north Texas.

``What I've seen, just at my porch light and I've been watching closely are several species of noctuidae or noctuid moths,'' Hobson explained. ``This is the largest family of moths period. The abundance of moths this year is higher than usual, but it's a phenomenon that happens here not uncommonly.''

Hobson said the life span of an adult moth is only about 30 to 40 days, and most of that time is spent as a larva. Adult moths are short-lived, maybe a week to 10 days. So the numbers should be tapering off in the next week or so, but only long enough for new eggs to become armyworms and then moths again. In Oklahoma, the moths can go through three to six generations, depending on the weather.

``There's been a lot of studies done on this species, commonly called armyworms or cutworms,'' Hobson said. ``They can be important crop pests, because the larvae will feed on things like Bermuda grass and Johnson grass. The adults, the moths we see flying around now, aren't feeding or damaging at all,'' he added. ``The concern agriculturally is the larvae. They feed on a large variety of crops, grasses and some legumes.''

It's in this larva stage that the insects are likely to do damage to lawns and gardens,'' said Craig Evans, horticulturist with the Oklahoma State University Extension Service in Cleveland County.

Although the worms may decide to take a lunch break on that finally fruiting tomato plant, Evans said folks shouldn't take drastic measures to get rid of them.

``The very negative thing is that the caterpillars eat the plants.

``They'll hide during the day under mulch or hay, and at night they may cut an entire tomato transplant down,'' Evans said. ``There are thousands of species of moths, and very few of them have the impact of armyworms. It's only when they get large and populations get out of control that we need to step in and do something.''

Evans said there's no use trying to use harsh pesticides to kill the adult moths, because they don't do any damage and they've most likely already laid their eggs.

``It may make you feel good to kill an adult moth, but if a female can lay up to 200 eggs, it's worthless,'' he said. ``We recommend not to try to kill the flying adult moths.''

Hobson said in the next few weeks, nature will most likely take care of the moth problem naturally. Some birds and bats consider the adult moths dinner, he said, and later on, robins and other insect-feeding birds will feast on the worms. Interestingly enough, Hobson said, anyone looking toward the sky at twilight can likely observe the bats diving for the moths this time of year.

``The adult moths will be laying their eggs this time of year in clusters. They will hatch into loopers in about five to 10 days,'' Hobson said. ``All of this will send local wildlife into a frenzy.''

``Think of it as an entomological grocery store. They'll take adults now and loopers later,'' he continued. ``There will be a lot of things happening from this, and the birds, especially, are going to love it.''

The future infestation of armyworms and moths also depends a lot on the weather. Conditions have to be just right for the caterpillars to survive long enough to become moths. For example, if the soil was really wet when the eggs were hatching, fungal organisms could destroy the larvae.

``Since other animals count on these insects for their next meal, it's important not use harmful pesticides, like diazanon, to try to kill the armyworms. Doing so could harm the food chain,'' Evans said.

If the armyworm population is so out of control that something needs to be done, Evans suggests using BT (Bacillus thuringiensis), which won't harm other creatures that may decide to feast on an infected worm. The product is sold under brand names like Dipel and Thuricide, and can be purchased at local garden stores.

``It very quickly stops the worms from feeding and acts as a stomach poison,'' Evans said. ``If a bird decides to eat the worm while it's wiggling around on its death bed, the BT won't hurt the bird.''

Hobson, who prefers people not use any chemical and simply let the creature be, said there are biological ways to stop worm infestation, such as bringing in tiny wasps or tiny flies to eat the worms, if a large amount of damage is being done. They do a pretty darn good job of controlling the larvae, he said.

While the general human population considers this moth infestation and pending armyworm infestation a bit of a nuisance, Hobson said it's events like this that help us learn more about nature.

``It's a wonderful thing to watch. They're a wonderful educational tool,'' he said. ``I have a 5-year-old, and he thinks they're marvelous.''

``He caught one of the adult moths, and he wanted to know why there were so many, how long it would live and what to feed it,'' Hobson added. ``I encourage anyone to just catch one in a jar and watch it for a while.''