Hornworms cause extensive damage in quick fashion to the nightshade family of plants. The tender leaves of tomato, pepper, potato and eggplants are the perfect diet for newly hatched worms. It’s not uncommon to spot butterflies or moths hanging out around your vegetable garden, but not all of them are beneficial. Even monarch butterflies can be a problem while in the caterpillar stage.
However, hawk moths are by far the worst problem. Some species in the Sphingidae family of moths will lay their eggs on plants.
The resulting larvae, commonly called hornworms, feed on these plants until they’re ready to enter the pupal stage. Chances are, you’re already using neem oil on tomato plants, but will this natural remedy work on the hornworm as well.
Tomato Hornworm (Manduca quinquemaculata)
The official name for this pest is the five-spotted hawkmoth. As the common name suggests, adults will lay their eggs on tomato plants and other members of the nightshade (Solanaceae) family. The adults are most often attracted to plants with large, fragrant white flowers where they drink the nectar and lay their eggs on nearby crops. The eggs are often placed on young growth near the plant’s stem, and the resulting green caterpillars will munch on the plant, venturing further out to portions that have partial shade cover during the day. Visually, tomato hornworms are green with 8 V-shaped white markings along their abdomen and a rear-facing horn on their last segment.
Tobacco Hornworm (Manduca sexta)
Like the five-spotted hawkmoth, the tobacco hawk moth also known as tChe arolina sphinx moth. Much like their siblings, they feed on members of the nightshade family, although this species prefers tobacco when available. Unlike tomato hornworms, tobacco hornworm caterpillars have straight white markings, and their rear horn is red.
Can You Use Neem Oil For Controlling Hornworms?
It might be of little surprise that neem oil can combat some species of the hornworm. There are two species in particular that attack crops for which Neem is a viable solution.
Which Hornworms Will Neem Destroy?
In theory, neem oil will work against all 1,450 species of the hornworm. However, adults don’t always lay their eggs on plants that have been domestically cultivated. We’ll focus on two specific species, although the neem treatments should apply to any other species which attack your garden.
Neem Oil Effects
Two forms of Neem are effective against hornworms
· Raw Neem
· Clarified Neem
100% percent cold-pressed raw neem oil is the unmodified extract from Azadirachta indica and contains Azadirachtin as its primary organic insecticide, along with four other active ingredients. This form of Neem is too powerful for topical applications but is used as a soil drench. When ingested, the Azadirachtin mimics the hornworm’s hormones, causing it to stop eating. It also can arrest development into the pupal stage, preventing the hornworm from reaching adulthood to reproduce.
Clarified hydrophobic neem oil extracts Azadirachtin from raw Neem used in other commercial pesticides. This form of Neem contains .5 to 3% percent Azadirachtin, so it is safe for use topically. Unlike raw Neem, clarified Neem also attacks pests topically, clogging their breathing holes and causing them to suffocate.
Note: Neem oil is non-toxic to humans in small doses, so it is safe to treat your tomatoes and other food crops. However, it is best to perform a soil soak or foliar application at least 24 hours before harvesting, so there’s less contamination.
Tip to Find Hornworms?
The Black Light Flashlight Trick…
If you are experiencing a tomato hornworm attack at the moment and can’t locate the culprits, one of the quickest and easiest methods to find them is by using an inexpensive black light flashlight in your garden at night.
Hornworms have a translucent body that will light up with a black light. The UV rays create a glow on the worms against the plants, making them easy to spot. Simply walk your rows, and shine the light on your foliage. It is amazing to see them light right up!
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