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.
A dry cough is known as ânonproductiveâ; whatâs called a wet cough is âproductiveâ (i.e. mucous-producing). The most common causes of a dry cough are asthma, allergies and acid refluxâin which other symptoms may or may not be present. Asthma Asthma, a condition in which the bronchial tubes become inflamed, usually causes wheezing, tightness in the chest and shortness of breath.