Tom Turpin
Professor of
Purdue University







Twilight beckons insect Jekyll and Hyde

The best thing about some hot summer days is that they turn into cooler summer evenings. That's when the accumulated heat of day slowly begins to escape the clutches of the earth. It's a time of day when humans appear in backyards to lounge in lengthening shadows, courtesy of the decaying rays of the westbound sun.

Twilight is also the tiem of day when hawk moths descend on flower beds to sip nectar from awaiting blossoms. Hawk moths are medium to large motths that are strong fliers. It is because of their speed of flight and rapid wing beat that they are named after that bird of prey, the hawk.

These moths also are called hummingbird moths. Most feed from flowers like hummingbirds and, in some cases, are about the same size as these diminutive birds. They even hover in front of flowers like these birds and use their proboscis to extract nectar from the blossoms.

In addition to being called hawk or hummingbird moths, these insects also are called hornworms or sphinx moths. Larvae of hawk moths feed on plants. The most commonly observed of the hawk moths conosumes tomato foliage as a larva and is called the tomato hornworm. Most gardeners recognize this insect as a serious pest of tomato because of the amount of leaf tissue that it can consume before it crawls from the plant to form a pupa. The insect then emerges from the pupa as a moth and begins to spend its evenings looking for flowers in search of a little sip of nectar.

The tomato hornworm is truely one of the Dr. Jekyll and Mr. Hyde insects in this world. As a larva, it feeds on and damages our tomato plants, so we consider it a pest and try to get rid of it. As an adult, it is a beautiful and graceful moth that is fun to watch as it gathers nectar from our flower beds.

Most children have at one time or another tried to catch a hawk moth as it hovered in front of flowers in the early evening hours. Most are not successful. After all, in the adult stage, a hawk moth is one of the fastest insects known, reaching speeds of nearly 30 mph.  


Writer: Tom Turpin
Editor: Andrean McCann