Tehran Enjoys Respite From Annoying Whiteflies

The tiny white insects that swarmed the capital Tehran in the past summers have not been present so far this year, much to the relief of the residents who already suffer such distressing metropolitan challenges as horrendous traffic jams and air pollution.
Although no definite reason for their presence, and now absence, is known, experts and officials have presented a number of theories. 
Alireza Davoudnejad, an environment expert at Tehran's office of the Department of Environment, has highlighted three factors which are chiefly responsible for their invasion, namely changes in the ecosystem, expansion of their host plant and warm weather. 
"Excessive spraying of pesticides had eliminated the species that feed on whiteflies, thus allowing them to increase in number," he said, Zist Online reported.