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From egg to adult moth: The amazing life cycle of the diamondback moth revealed!
The diamondback moth (Trichoplusia ni) is a medium-sized moth belonging to the family Noctuidae, commonly known as fall moths. Its name comes from its primary host plants and its unique crawling behavior, with a particular preference for cruciferous greens such as cabbage, bok choy, and broccoli. The larvae of the diamondback moth are called "ringworms" because their backs form an arched ring when they move. Although plants from the cruciferous family are preferred, over 160 plant species can serve as hosts for diamondback moth larvae. The adult diamondback moth is a migratory moth found throughout North America and Eurasia, from southern Florida to northern British Columbia.
Although diamondback moth larvae are considered small pests, their wide distribution and resistance to many insecticides make management increasingly difficult.
Each stage of the life cycle
Mating
Diamond moths raise their abdomens and extend their wings when preparing to mate. Males fan the hairs on their abdomens and open their genital clamps to attract females. Mating usually occurs around 2 a.m., but may occur as early as 12 a.m. to 4 a.m. Females will seek out host plants to lay their eggs after mating.
Egg stage
The eggs of the diamondback moth are generally yellow-white, dome-shaped, with obvious ridges, and are about 0.6 mm in diameter. The female can lay 1,000 to 2,000 eggs a day, which hatch after about three days. Usually, the eggs are laid individually on the underside of leaves.
Larva stage
When the larvae first hatch, they are green and slightly hairy, but then they gradually lose their hair, leaving only a few fine hairs. They move in a circular manner and can reach a body length of 3 to 4 cm. Larvae at this stage undergo four to seven molts, which takes a total of about 9 to 14 days.
Pupal stage
During the pupal stage, the diamondback moth attaches to the underside of a leaf and forms a silky pupa. This stage usually lasts 4 to 13 days, and the size of the pupa varies between sexes, depending on the ambient temperature.
Adult moth
The adult diamondback moth has gray-brown forewings and light brown hindwings. It is about 2.5 cm long and has a wingspan of about 3.8 cm. The period from egg to adult moth is generally 24 to 33 days.
Distribution and Migration
The diamondback moth is widely distributed in North America and Eurasia. As the seasons change, the diamondback moth in North America migrates from Mexico to Canada. These diamondback moths in particular tend to overwinter in Mexico or Southern California during the winter.
The activity of diamondback moths is closely related to temperature. When the temperature in the area exceeds 16°C, they will begin to migrate northward.
Defense and Enemies
Diamond moth faces threats from multiple predators and parasites. Common predators such as spiders, ants and ladybugs pose a threat to the eggs and larvae of the diamondback moth. According to studies, about 50% of the eggs and 25% of the larvae can be removed within three days. Among parasites, the most common is the orange lice, which is the main parasite according to the latest research and is more frequent in winter and autumn.
Conclusion
The life cycle of the diamondback moth illustrates the adaptability and reproduction strategies of animals in nature. The interaction between the survival of this organism and its environment is becoming increasingly noteworthy. How can we understand and respond to its impact on agriculture?
