WSU Extension

Hortsense

Tomato
 
Disease
Anthracnose 
Blossom-end rot 
Catface 
Curly top (Beet curly top virus) 
Late blight 
Mosaic viruses 
Physiological leaf roll 
Sunscald 
Verticillium wilt 
White mold 
Insect
Aphids 
Brown marmorated stink bug 
Colorado potato beetle 
Flea beetles 
Slugs 
Spider mites 
Tomato hornworm 



print version| pdf version| email url    
Caption: Tomato hornworm larva
Photo by: W. Cranshaw, CSU
  
Tomato : Tomato hornworm
(revision date: 1/27/2016)


Biology
The tomato hornworm is the larva of a sphinx moth. The adult moth has a wingspan of up to 4"-5". Wing color is generally mottled gray. Mature caterpillars may reach up to 5" in length but are typically around 2" long. They are generally pale green with some white markings, although dark purple hornworms are sometimes seen. The mature hornworms are characterized by a short, curved, green to reddish horn on the back end. The larvae feed on the leaves of tomato, potato, and related plants and may cause serious defoliation. Symptoms of feeding include leaves chewed down to the midrib and dark pellets of frass (excrement) on or under plants.
Management Options


Non-Chemical Management
  • Hand-pick and kill hornworms. This is usually sufficient control for the home garden.
  • Natural enemies including birds, spiders, and parasitic wasps help control caterpillar populations. Avoid use of broad-spectrum insecticides which can kill beneficial insects.
Select non-chemical management options as your first choice!

Chemical Management

Apply Bt when first noticed. Hornworms will soon quit feeding but may remain on plant a few days. If Bt is chosen, be sure to apply when insect is feeding. The best time to apply is when caterpillars are young. Use a spreader-sticker with liquid Bt formulations.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Azamax Botanical Insecticide, Miticide, & Nematicide [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 71908-1-81268
  • Bonide Thuricide BT Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 4-226
  • Bug Buster-O [Organic]
    Active ingredient: pyrethrins  |  EPA reg no: 1021-1771-54705
  • ferti-lome Dipel Dust
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 7401-290
  • Safer Brand Caterpillar Killer for Trees, Shrubs & Vegetables Conc II [Organic]
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 70051-106-42697
  • Safer Brand Caterpillar Killer/Trees, Shrubs, & Vegetables Conc
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 42697-23
  • Safer Brand Garden Dust RTU [Organic]
    Active ingredient: Bacillus thuringiensis subsp. kurstaki  |  EPA reg no: 36488-25-42697
  • This list may not include all products registered for this use.
Images

+ Show larger images

 
Caption: Tomato hornworm larva
Photo by: W. Cranshaw, CSU
Caption: Tomato hornworm larva
Photo by: W. Cranshaw, CSU