Tobacco hornworms are a major plant pest across the United States. They are also masters of disguise.
The Mississippi State University Extension Service has demonstrated this in a game of hide-and-seek that it shared to its Facebook page on August 23.
"Let's play a game," it said. "Can you find the tobacco hornworm(s) in this picture?"
The picture shows a flourishing tomato plant that, on first glance, does not exhibit anything unusual.
"Even large caterpillars are well-camouflaged and difficult to spot, though their feeding damage and fecal droppings often give them away," the MSU Extension Service said.
Tobacco hornworms are the larval stages of the Carolina sphinx moth, Manduca sexta. They feed on the leaves, stems, blossoms and fruits of their host plants, and are particularly partial to members of the nightshade family. This includes tomatoes, peppers, potatoes and eggplants.
Of course, as their name suggests, they also often target tobacco plants.
"These caterpillars do 90 percent of their feeding in the last five to six days of their larval life," the MSU Extension Service said. "This is why a tomato plant that looked fine on Saturday can be nearly stripped of leaves by Tuesday morning. Even one big hornworm can eat a lot of leaves, and if there are several caterpillars on a plant, the damage can be dramatic."
The caterpillars themselves are cylindrical in shape and can reach lengths of roughly 4 inches at maturity. They are bright green with diagonal white stripes along the length of their body. They also have a distinctive orange-red tail spine, hence the name "horn" worm.
If you look closely, you should be able to find two tobacco hornworms in the picture.
"When ready to pupate the caterpillars crawl to the ground, burrow in and form a "naked" pupa (no cocoon)," MSU said. "The pupal stage lasts 14 days or so in the summer, but they also overwinter as pupae in the soil."
These big caterpillars grow into big moths, with wingspans of over 4.5 inches. "The wings are drab, mottled gray, but the top of the abdomen has a row of six orange or yellow spots on either side," it said.
These moths then use their excellent sense of smell to find small, isolated plantings of tomatoes to lay their eggs, making them very difficult to deter. Luckily, there are some effective control measures:
"The insecticides used to control fruitworms, stink bugs and other more important pests usually provide excellent preventive control of hornworms. Insecticides such as zeta-cypermethrin, permethrin, and Spinosad are all very effective," MSU said.
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