Boll weevil

What you are looking at

Small punctures in cotton squares, the flower buds that would otherwise open and set a boll, each surrounded by a slightly raised, warty scar. A punctured square yellows, withers and drops from the plant within days, a stage growers historically called flared squares, since a heavily infested field carried noticeably fewer developing bolls than punctures would suggest on their own. Cut a puncture open and there is often a grubby white, legless, curved larva feeding inside.

The adult is a greyish-brown beetle about 6 mm long, distinguished from almost anything else on a cotton plant by a long curved snout that runs to roughly a third of its total body length, used to bore the puncture and lay a single egg inside it.

A genuine eradication success story

Few pests illustrate the difference between “established” and “everywhere it could survive” better than this one. Native to Mexico and Central America, it crossed into Texas in the 1890s and spread through the entire United States Cotton Belt within thirty years, becoming the single most consequential agricultural pest in the country’s history and the direct inspiration for the boll weevil monument in Enterprise, Alabama, erected because the crop failures it caused forced a shift to more diverse farming that left the region better off in the long run.

A coordinated, decades-long eradication campaign combining pheromone traps and targeted, precisely timed insecticide applications has since removed it from nearly every cotton-growing state. The most recent reporting places the only surviving US population in a small area of the Lower Rio Grande Valley in extreme southern Texas, kept under active suppression rather than left to recover. It remains established through Mexico and parts of Central and South America, and it has never established anywhere outside the Americas.

What to do about it

Outside the Lower Rio Grande Valley, a weevil matching this description is unusual enough to be worth reporting to the state eradication programme or plant health authority rather than treated as a routine field pest, since catching a reintroduction early is what keeps decades of progress from being undone.

Within an area still managing a population, destroy cotton stalks promptly after harvest rather than leaving them standing, and support the area-wide pheromone trapping programme rather than relying on individual field measures alone, since this is a pest that coordinated regional action brought under control and individual action alone did not.

What it gets mistaken for

Capsid bugs leave ragged marks on leaves and shoot tips rather than the small, round, warty-rimmed punctures this weevil leaves specifically on squares and bolls. A dropped, yellowing flower bud carrying a clear puncture mark is the more distinctive sign to look for.