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.
These coughs may occur at the start of the illness or most often, towards the middle or the end of the infection. Other causes of a dry cough include: 1  Side-effect of medication â some medicines, particularly those for high blood pressure, can result in a dry cough. 2  Hayfever-this is an allergy to grass and tree pollen.