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.
Nonproductive Cough. A nonproductive cough is one that does not bring up any mucus or other secretion. Also known as a dry cough, a nonproductive cough often is caused by some sort of irritation in the throatâa tickling sensation, for example. Swelling of the airways also can cause a dry cough. Conditions associated with this type of cough include asthma and bronchitis. Sometimes a cold, flu, or other upper respiratory illness can trigger a nonproductive cough, although these illnesses can cause a productive cough as well. Productive Cough