He estimated how many species of insects lived on each plant species in England, and then extrapolated that figure across the whole planet. âIf we say 400,000, we shall, perhaps, not be very wide of the truth,â he wrote. Today, scientists know the Westwood figure is far too low.
Symptoms: A chronic dry cough that's worse at night, disturbing sleep, and sometimes with wheezing and shortness of breath. Causes: An irritating night cough is often the first sign of asthma, especially in children, but you can develop it at any age. It's also a sign asthma is worsening or not being well controlled.
Cause of a Dry Cough. As mentioned, most coughs may initially start off as a non-productive cough (dry cough) but can progress to a productive cough (wet cough) with time. Apart from certain infections, any irritation of the airway as result of allergies, air pollution, cigarette smoking and certain drugs may result in a dry cough. Infectious Causes