Hawk moths, also known as sphinx moths, are a group of insects in the family Sphingidae. They are medium to large moths with long, narrow forewings and shorter, broader hindwings. There are over 1,500 species of hawk moths found worldwide, with around 200 species in North America alone. Some well-known hawk moths include the tomato hornworm, tobacco hornworm, hummingbird moth, and grapevine hawk moth.
While the adult moths are important pollinators, their larval caterpillars are voracious eaters and can cause significant damage to agricultural crops and ornamental plants. However, only a subset of hawk moth species have larvae that are considered major pests. Many other hawk moth caterpillars do little, if any, damage. So the extent of damage caused by hawk moths overall depends largely on the specific species present in an area.
Do tomato hornworms cause damage?
The tomato hornworm (Manduca quinquemaculata) is one of the most common and destructive hawk moth pests in North America. The green, plump caterpillars can grow up to 4 inches long and are known for quickly defoliating tomato plants. Tomato hornworms also feed on eggplant, pepper, potato, and other plants in the nightshade family. A single caterpillar can consume dozens of leaves, wiping out an entire tomato plant in a matter of days. For this reason, tomato hornworms are considered a major pest by home gardeners and commercial tomato growers alike. Their voracious feeding can lead to complete loss of fruit and plant if infestations are severe. So tomato hornworm caterpillars certainly have the potential to cause extensive plant damage.
Do tobacco hornworms cause damage?
Closely related to the tomato hornworm is the tobacco hornworm (Manduca sexta), named for its habit of feeding on tobacco plants. As larvae, these large green caterpillars voraciously consume leaves of tobacco, tomato, potato, peppers, eggplant and other Solanaceous crops. A tobacco hornworm outbreak can defoliate entire fields of tobacco plants, causing dramatic financial losses for farmers. So tobacco hornworms are considered a major agricultural pest. Home gardeners may also find them feeding on tomato plants in the vegetable garden, where they can quickly strip plants of leaves. The potential for damage from tobacco hornworm caterpillars is high given their wide host range and rapacious appetite.
Do hummingbird moths cause damage?
Hummingbird moths comprise several fast-flying hawk moth species in the genus Hemaris. They get their common name from their ability to hover in front of flowers while feeding, similar to hummingbirds. Probably the best known is the hummingbird clearwing moth (Hemaris thysbe), found throughout North America feeding on nectar from various flowers. The larvae, which are light green caterpillars with white or pale yellow stripes, feed on the leaves of viburnum, honeysuckle, snowberry and other woody ornamental plants. While they may nibble on plant leaves, hummingbird moth caterpillars do very little damage and typically go unnoticed in gardens. So hummingbird moths are not considered pests. Their role as important pollinators far outweighs the minor foliar feeding by their larvae.
Do grapevine hawk moths cause damage?
Grapevine hawk moths (Deilephila elpenor) are common visitors to gardens where they feed on nectar from flowers. The plump, green and purple striped caterpillars feed primarily on grapevines, but may also eat leaves of Virginia creeper, ampelopsis and other woody vines. While they eat portions of vine leaves, grapevine hawk moth caterpillars are not usually present in high enough numbers to significantly damage grape crops. Their minor leaf feeding typically goes unnoticed by most growers. Home gardeners with just a few grapevines likely won’t see any negative impact. So in most cases, the foliage feeding by grapevine hawk moth larvae causes little or no meaningful damage overall. Their role as pollinators is viewed as more important.
Do white-lined sphinx moths cause damage?
The white-lined sphinx moth (Hyles lineata) is a common hawk moth found throughout North and Central America. As caterpillars, they feed on the leaves of a diverse range plants, including willow, elm, apple, plum, grape, and tomato. High populations can result in defoliation of host plants, but significant damage is not commonly reported. The white-lined sphinx caterpillar’s impact is viewed as minor compared to other caterpillar pests. And their value as pollinators in their adult moth stage outweighs the small amount of foliage they consume as larvae. Overall, white-lined sphinx moths are not a pest species causing major economic damage. Their intricate caterpillars may munch on leaves in gardens, but widespread devastation is rare.
Do big poplar sphinx caterpillars cause damage?
The big poplar sphinx (Pachysphinx modesta) is one of the largest sphinx moths, with a wingspan up to 5 inches. Their very large green, brown, and white striped caterpillars can grow over 4 inches long. They feed on the leaves of poplars, cottonwoods, willows and other trees. While they eat quite a bit of foliage while mature, populations are typically low enough that even extensive leaf nibbling rarely harms their host trees. A healthy poplar or cottonwood will quickly replace any eaten leaves without real consequence. So the big poplar sphinx caterpillar generally does not inflict serious damage, even in parks or urban areas lined with their favored tree hosts. Any cosmetic harm is temporary and not a major concern.
Do not all hawk moth caterpillars damage plants?
While certain hawk moth larvae like tomato hornworms and tobacco budworms can damage crops, many other hawk moth caterpillars do negligible harm to plants. Species like hummingbird moths, big poplar sphinx, grapevine hawk moth, and white-lined sphinx moths have larvae that eat plant leaves but rarely in high enough numbers to warrant control measures. The minor cosmetic damage they inflict is tolerated by most growers. Other hawk moth larvae feed on inconsequential weeds and cause no damage to valued plants. So it’s inaccurate to say all hawk moth caterpillars are destructive pests. Many have only minor impacts on foliage despite their large appetites. And their essential pollination services as adult moths can outweigh any larval damage.
Do hawk moth caterpillars provide any benefits?
Despite the potential for some species to damage crops and ornamental plants, hawk moth caterpillars also provide ecological benefits:
– Food source for predators: Many birds, small mammals, and other insect predators prey on hawk moth larvae, helping to control their populations while gaining nutrition.
– Nutrient cycling: As part of the food chain, hawk moth caterpillars help break down and cycle nutrients through the ecosystem. Their frass (excrement) contributes organic matter to the soil.
– Pollination: Adult hawk moths are important pollinators of many night-blooming flowers, like petunias, jasmine, and evening primrose. Their long proboscises allow them to access nectar from tubular flowers.
So while certain species cause damage, the hawk moth family overall contributes positively to natural ecosystems and gardens in multiple ways. Their ornamental caterpillars and essential pollination services outweigh the harm caused by a few pest species.
Conclusion
Only some hawk moth larvae are significant agricultural and horticultural pests, particularly the tomato hornworm and tobacco hornworm. Many other hawk moth caterpillars do little, if any, damage to plants while contributing to pollination and nutrient cycling as adults. Each species must be evaluated separately. Well-known pests like the tomato hornworm can certainly wreak havoc in vegetable gardens and fields. But innocent species like the hummingbird moth do not warrant control measures. In fact, their pollination services make them desirable visitors to gardens and natural areas. The diverse hawk moth family features relatively few notorious plant pests amidst many innocuous and ecologically beneficial species. While certain problematic larvae require management, most hawk moth caterpillars are harmless and even contribute positively to ecosystems.