Quickly Eliminate Tomato Hornworms Before They Destroy Your Garden
For gardeners, few pests are as dreaded-or as destructive-as the tomato hornworm. Seemingly overnight, large numbers can appear, stripping plants of leaves and fruit as if a biblical plague has descended. One day your tomato plants are thriving; the next, they're ravaged. What's worse, the culprits are masters of disguise, blending seamlessly into the foliage. But there's a surprisingly effective way to detect and eliminate them: using ultraviolet black light.
What Are Hornworms?
Two common species in the U.S. and Southern Canada-the tomato hornworm and the tobacco hornworm-pose a major threat not only to tomatoes but also to eggplants, peppers, potatoes, and tobacco plants. Their green coloration offers near-perfect camouflage against leaves and stems, making manual detection and removal incredibly difficult. Even when you find one, others are almost certainly hiding nearby.
How to Detect Hornworms
Many gardening guides suggest looking for the pests' dark green or black droppings on leaf surfaces, often clustered near the top of plants. While this can sometimes reveal their location, it's a time-consuming and often frustrating process-especially in larger gardens.
A far more effective method is to use an ultraviolet (UV) black light at night. Hornworms fluoresce under UV light, glowing brightly against the dark foliage and making them impossible to miss. We field-tested this using a 395 nm UV LED strip powered by a portable battery. The result? Dozens of worms were easily spotted and removed in minutes.
What to Do When You Find Them
Once located, you have several options:
Feed them to chickens (if you have them).
Drop them into a bucket of soapy water.
Squish them (if you prefer immediate disposal).
Since hornworms often hatch in clusters, repeat inspections are necessary. Make nightly checks until the infestation is under control.
How to Make a UV Hornworm Detection Light
You can easily assemble your own portable UV light for nightly patrols:
Use a 12V UV LED strip (395 nm is ideal).
Power it with a portable 12V battery pack (e.g., an 8×AA battery holder with a DC plug and switch).
Optional: Mount the strip into a short section of aluminum track for durability, or wrap it around a stick or handle.
If you prefer a ready-made solution, consider purchasing a battery-powered UV LED strip kit, which typically includes a 20″ light and battery pack.
Buy a section of our High Density Ultra Violet Strip Light. This outputs about 395nm which is in the UV-A spectrum range – qualifying as a black light. The strip comes with adhesive backing and a 2.1mm female barrel plug connector on one end.
Proven Effectiveness
We lent our UV light to a local tomato grower who had been manually removing only two or three hornworms per day. On her first night using the light, she found over 20 worms in 30 minutes-and 17 more the following night. After that, the population was under control. Her plants recovered, leaves regrew, and fruit damage ceased.
Other Uses for UV Light
The same UV light can help detect other pests like scorpions or bedbugs. It's also used in forensic applications-for example, detecting certain bodily fluids. It's a versatile tool both in the garden and beyond.
Act Now-Save Your Tomatoes
Don't wait until hornworms take over. With a simple UV light, you can spot them quickly, remove them efficiently, and protect your garden night after night.
