The date stone beetle or button beetle, Coccotrypes dactyliperda, is an insect belonging to the bark beetles (Scolytinae). It feeds on and spends part of its life cycle in dates, the fruits of the date palm (Phoenix dactylifera). Because of its damage to dates, it is considered a pest.
Adults of the species are reddish-brown and 1.8–2.3 mm (0.07–0.09 in) long, with a convex shape and hairs on the dorsal surface. Characteristic of beetles, they have four wings, with the pair of hardened forewings protecting the pair of hindwings used for flying. They chew a round hole into green unripe dates, causing the fruit to drop 1 or 2 days later.
The species uses the haplodiploid sex-determination system: females are diploid while males are haploid; unmated females produce male offspring by parthenogenesis while mated females produce both male and female offspring. Both in beetles from collected date stones and in laboratory cultures, about 85–93% of the adults are females.
When a flying unfertilized female reaches a target such as a date stone, sweet almond, betel nut, nutmeg, cinnamon bark or a button made from vegetable ivory, hence the name "button beetle"), she bores a hole in it and excavates a chamber. (Males cannot penetrate the stone.) Inside, she produces a brood of four or five males. She mates with the first son that reaches maturity, then proceeds to eat them all. She then enlarges the chamber and lays a brood of about 70 offspring. Some of the females mate with their brothers.
It takes about 22–25 days for an egg to develop through a larva and pupa into an adult, with males developing faster than females. Mated females live on average 73 days while unmated ones live on average 63 days.
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—Mark Twain [Samuel Langhorne Clemens] (1835–1910)
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—Alfred Döblin (1878–1957)
“After the planet becomes theirs, many millions of years will have to pass before a beetle particularly loved by God, at the end of its calculations will find written on a sheet of paper in letters of fire that energy is equal to the mass multiplied by the square of the velocity of light. The new kings of the world will live tranquilly for a long time, confining themselves to devouring each other and being parasites among each other on a cottage industry scale.”
—Primo Levi (1919–1987)