Weevil

• The town of Enterprise, Alabama, raised a monument in its honour in 1919: the pest forced farmers to diversify into peanuts and they fared far better than they had with cotton.
• A decades-long eradication programme based on pheromone traps and coordinated treatments has removed it from almost all of the United States, one of the few cases of a pest eradicated at continental scale.
• The adults overwinter hidden in the leaf litter at the field margins and reappear with the following crop.
• It is the most destructive agricultural pest in the history of the United States. It entered from Mexico around 1892 through Brownsville, Texas, and in the five years following contact, cotton production would fall by around 50% in each affected area.
• Its cumulative impact has been put at more than 16 billion dollars up to 2009, around 91 billion adjusted to current prices.
• It changed the social history of the South: it ruined hundreds of landowners and pushed sharecroppers and labourers to leave for the north, in what is known as the Great Migration.
• And it has a monument. In 1919 the townspeople of Enterprise, Alabama, put up a statue in its honour, thanking it for forcing them to abandon the cotton monoculture and switch to peanuts. It is the world's first monument dedicated to an agricultural pest.
• The national eradication programme, begun in 1978, has eliminated it from almost the entire country; it holds out only in the lower Rio Grande valley, in Texas, and in northern Tamaulipas.
• A single pair can leave two million descendants in one season.
• Despite forty years of almost exclusive use of malathion in the eradication programme, it remains susceptible to that insecticide, something exceptional.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Cotton crops and wild cottons

Size at birth

The larva is a white legless grub with a brown head that reaches about 12 mm before pupating inside the flower bud

Sexual maturity

The newly emerged adult feeds for about five days before mating; six to ten generations are completed a year depending on the region

Gestation / incubation

The eggs hatch in 2-5 days; the larva goes through four instars in 7-18 days and the pupa lasts 4 to 10 days; the full cycle ranges from 16 days at 32 °C to 46 days at 18 °C

Litter / clutch size

About 200 eggs per female over 10-12 days, with a recorded maximum of 251 at 25 °C; she normally lays a single egg per flower bud and seals the entrance with a mixture of faeces and secretion

Sources consulted: https://es.wikipedia.org/wiki/Anthonomus_grandis; Bugwoodwiki, Anthonomus grandis grandis; NCBI PMC10380894; LSU AgCenter, ficha Boll weevil; NCBI PMC10380894, tabla de vida en Brasil; Animal Diversity Web; Texas A&M, guia de insectos; Animal Diversity Web, Anthonomus grandis; IUCN GISD, ficha Anthonomus grandis; Bugwoodwiki

Best time: It overwinters in diapause in the leaf litter and returns to the cotton fields between March and July, with the emergence peak in late May