Ever since I first read about tomato hornworms glowing under ultraviolet light at night, I’ve wanted to see it for myself. But thanks to nesting cardinals I don’t find many hornworms. The large caterpillars must be one of their favorite brands of baby food. When I finally spotted one earlier this summer, we took photos and a short video that night. We simply used a penlight with an ultraviolet setting.
Without intervention a single hornworm can devour a tomato plant pretty quickly. Remember, the caterpillar stage of life is all about consuming their preferred plant material in the greatest possible quantity. The daytime hornworm photo below shows how well they blend with leaf coloring. If their damage isn’t too apparent yet, they are easily missed during daytime examinations of the tomato plant. Looking for them after dark with a cheap ultraviolet light makes the job much easier.
A surviving tomato hornworm eventually becomes a large moth called the five-spotted hawkmoth. If you grow night blooming jasmine, you may have noticed hawkmoths around the flowers at dusk. They are sometimes confused with hummingbirds.
Tomato Hornworm Images and Video
