Answer: The answer is Geckos die from eating poisoned flies
Explanation: In "Top of the Food Chain" by T.C Boyle, several events happened. However, the one that happened first was the geckos eating the poisoned flies. The narrator tells how they discovered the death of a big amount of lizards. The geckos feasted on the contaminated and poisoned flies without noticing it and that is why they started to die.