JULY
2000

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

7-13-00

Not All Moths Are Fly-by-Night Creatures

Moths and butterflies are insect cousins. Both are classified in the Order Lepidoptera, which means scale wings. Both have scales on the wings. Immatures of both butterflies and moths are called caterpillars. Caterpillars are armed with chewing mouthparts and most feed on plants. Adults of butterflies and moths are nectar feeders.

But there are differences between these closely related insects. One of the obvious differences is that butterflies are bright colored while moths tend to be drab looking. Butterflies have clubbed antennae. Moths, on the other hand, have fuzzy antennae without the club. Moths lay their wings down over their back when at rest. Butterflies hold their wings up or out when not in flight. And when the caterpillar turns into the pupal stage, moths generally spin a silk cocoon.

There is a difference when the insect changes from the immature to the adult stage. Butterfly larvae don't bother to cover up during the process. When they go into the pupal stage, they are naked. Moth caterpillars, though, generally spin a silken cocoon to protect the pupa. This is where the silk of the silkworm is generated.

Of course, all moths and butterflies don't follow these general rules. Some moths are bright colored. A few moth caterpillars don't spin cocoons, but they generally hide in the ground.

One behavioral difference is that butterflies fly during the day, and moths take wing at night. But not all moths fly at night. There are several moths that are out during the daylight hours.

One of the common day-flying moths is called a ctenucha moth. These brown- to black-colored moths with steel-blue bodies look much like wasps as they feed on flowers. Immatures feed on marsh grasses.

Another group of day-flying moths also resembles bees and wasps. These are the clear-winged moths. They are called clear winged because scales are absent on most of their wings so that the wing membrane is obvious.

Larvae of clear-wing moths are borers in roots and stems of plants. A few of the more than 100 species in North America are pests. Two of these pests are the peach-tree borer and the squash-vine borer. The squash-vine borer has very hairy, red hind legs and can be seen flying around squash and pumpkin plants in the bright sunshine. This can be bad for the plants since feeding by the borer will cause the vines to die.

The buck moth also flies by day. These moths have wings that are black on the outside and inside margins, with a white area in the middle. Buck moth larvae are black with sharp spines. These spines are stinging hairs, and anyone who touches the larvae will regret the experience. The larvae also have red spots on the sides and feed in groups. The red spot is considered a warning color when worn by insects, and it does apply in this case.

Sphinx moths, also called hawk moths, are probably the best known of the day-flying moths. These insects are fast fliers and feed at flowers during daylight hours in the fashion of hummingbirds. In fact, one of the sphinx moths has clear wings and is officially known as the hummingbird moth. The hummingbird moth is yellow and black in color and, because of its habit of visiting flowers, is frequently mistaken for a bee. 

Sphinx moths include several types, such as the common tomato hornworm. Yes, the immatures of these moths are called hornworms. Two of the most common are the tomato and the tobacco hornworms. Both are pests on these plants, but for those of us who don't smoke, it is hard to believe that anything that feeds on tobacco could be considered a pest.

So, while the most common flight behavior of moths is during the dark hours, there are some moths that prefer to be out and about during the day. In many instances, these insects mimic other insects in color and behavior. They commonly look and act like bees or wasps. After all, if you are out during the day, it pays to encourage the rest of the world to believe that you can sting. A good offense is a good defense to these fly-by-day moths!

 

Writer: Tom Turpin
Editor: Olivia Maddox