He no formal training in advanced mathematics and lived a fairly quiet and somewhat secluded life partly due to his past illness.
During World War II, the bureau shifted its focus to controlling rat and mouse populations in grain silos.
[2] After the war, Leslie expanded the application of his matrix method to study the growth rates of various animal species, including birds and beetles.
Second, he conducted groundbreaking studies on stochastic equations to better understand predator-prey and interspecies relationships, contrasting these with simpler deterministic models.
From 1948, Leslie collaborated closely with Thomas Park of the University of Chicago, who studied competition between Tribolium flour beetles.