AS an apprentice anthropologist, I once had the misfortune of attempting to converse with the Indian critical theorist Gayatri Chakravorty Spivak. Professor Spivak, who translated the work of the French philosopher Jacques Derrida and wrote the famous essay “Can the Subaltern Speak?”, was visiting Dhaka, Bangladesh, and I went to meet her. After patiently listening while I asked a series of dumb questions about discursive practice, she turned and said, cryptically, “I came for the mangoes.”

Ah, the mango. It may be a clichéd pitfall for the South Asian writer, but for this academic, famous for her impenetrable prose, the mango brought the esoteric down to earth. Ms. Spivak is regarded as one of the great minds of her generation, but in Dhaka, she was, like everyone else, there for the mangoes.

In Bangladesh, the obsession with the mango comes from its evanescence. The fruit’s intense seasonality means that even the more prosaic varieties are available for only a few weeks of the summer. The most prized is the langra: Its floral, slightly sour flavor is more complex than the overly sweet chaunsa or Alphonso mangoes. Aficionados love the langra in part because it is almost impossible to catch at its peak — too green and your tongue will swell and itch; a few hours late and its flesh turns to mush.

But this year, the langra is nowhere to be found. The markets are empty.

On the roads that lead into Dhaka, the precious fruit lies rotting by the truckload. The reason: chemical poisoning. The langras are said to be contaminated with formalin, a strong solution of formaldehyde that is sprayed on the fruit to extend its life.