Boll weevil
The boll weevil is a small beetle known for its destructive impact on cotton crops, first identified in the United States in southern Texas in 1892. This pest primarily feeds on cotton bolls, which are the seed pods of the cotton plant, and has historically been a significant threat to cotton growers across the southern United States and parts of Mexico. The beetle measures approximately 1/4 inch (1/2 centimeter) in length and is characterized by its reddish-brown to brownish-black body covered with coarse yellow hairs and a distinctive long snout or proboscis used by females to lay eggs inside cotton bolls.
Boll weevils undergo a life cycle that includes an egg-laying phase where a single female can produce between 100 to 300 eggs, leading to a potential population explosion if not controlled. Historically, the pest was widespread, particularly in cotton-growing states like Virginia, Kentucky, and California, but populations have been managed more effectively since the mid-2010s. The boll weevil's life cycle includes a feeding stage that lasts a few days, followed by larval development within the bolls, which can cause significant damage within just one or two weeks. The insect hibernates during winter, re-emerging in spring to continue its cycle. Understanding the biology and lifecycle of the boll weevil is crucial for effective management and control in agriculture.
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Boll weevil
The boll weevil is a small, destructive beetle first discovered in the United States in southern Texas in 1892. Since then, it has been an agricultural pest to generations of cotton growers. The boll weevil is named for the cotton bolls on which it feeds.
Kingdom: Animalia
Phylum: Uniramia
Class: Insecta
Order: Coleoptera
Family: Curculionidae
Genus: Anthonomus
Species: Grandis
Until the early 2010s, the boll weevil was common throughout the southern United States and Mexico wherever cotton was an important crop. It was particularly common in Virginia, Kentucky, Missouri, Oklahoma, New Mexico, Arizona, and California south to the Gulf Coast and Mexico. By the mid-2010s, Boll weevils occasionally infested crops in Louisiana and some areas of Texas, but the population was controlled.
The boll weevil may grow up to 1/4 of an inch (1/2 centimeter) long. Its body may be reddish brown to brownish black with coarse yellow hairs. Like other beetles, the boll weevil is divided into three main body parts. Those parts are the head, the thorax, or middle section, and the abdomen, or tail section.
The head of the boll weevil is its most unusual part. Extending from the front of the boll weevil's head is a long, narrow snout called a proboscis. It looks similar to an anteater's snout. The proboscis is a tube-like structure that the female boll weevil uses to bore holes into cotton bolls to lay eggs. The name weevil is given to all beetles with proboscises. Near the end of the proboscis are the two antennae of the boll weevil. The boll weevil uses its antennae to sense its surroundings. At the base of its proboscis are the boll weevil's compound eyes, or eyes with many lenses.
Behind the boll weevil's head is its thorax. The thorax is a rounded connecting piece between the head and abdomen. The boll weevil's front pair of legs extend from this part. The other two pairs extend from the insect's abdomen. Each of the boll weevil's six legs bears the same coloring and hair texture as the rest of its body.
Like other beetles, the boll weevil's front wings form hard, protective coverings that shield its more delicate, rear-flying wings from the environment. Each of the boll weevil's front wings forms an elytrum, or wingcase. The two elytra come together and rest on the boll weevil's back. When the boll weevil flies, it lifts its elytra and unfolds its rear wings that flutter and flap as they carry the boll weevil into the air. Like the rest of the boll weevil's body, the elytra are brownish or reddish with coarse yellow hairs.
Like the dung beetle, the boll weevil is named for its eating habits. This insect feeds mostly on cotton bolls. Cotton bolls are the yellowish, round seed balls of cotton. Sometimes, the adult boll weevil feeds on flower buds and leaves, but larval boll weevils live and feed in cotton bolls.
The mating season for the boll weevil is during the spring and summer after the adult boll weevils have returned to the cotton plant from their winter hibernation, or rest. The boll weevil feeds for several days before mating. After mating, the female bores holes into developing cotton bolls and lays one egg in each boll. A single female boll weevil lays between 100 and 300 eggs. Soon after mating and depositing their eggs, the adult boll weevils die. In their lifetime, a pair of boll weevils may produce two million offspring.
Boll weevil eggs hatch after three to five days. The larval young then begin feeding on the cotton boll in which they live. It takes one to two weeks for a larval boll weevil to destroy a cotton boll. At that time, the boll weevil larvae pupate, or develop, into a mature boll weevil. It remains active until the first frost. It then hibernates for the winter and emerges in the spring to mate.
The boll weevil has an average life span of about six months.
Bibliography
"Boll Weevil (Anthonomus grandis)." Insect Identification, www.insectidentification.org/insect-description.php?identification=Boll-Weevil. Accessed 17 Mar. 2024.
Perkin, Lindsey C., et al. “The Identification of Boll Weevil, Anthonomus grandis grandis (Coleoptera: Curculionidae), Genes Involved in Pheromone Production and Pheromone Biosynthesis.” Insects, vol. 12, no. 10, Oct. 2021, p. 893. doi:10.3390/insects12100893. Accessed 17 Mar. 2024.
Vallie, Sarah. "What to Know About Boll Weevils." WebMD, 23 Nov. 2022, www.webmd.com/a-to-z-guides/what-to-know-about-boll-weevils. Accessed 17 Mar. 2024.