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.
An acute dry cough that comes on suddenly and lasts up to two to three weeks is usually associated with a cold; whereas, a chronic dry cough over a long period of time (lasting more than eight weeks) may be caused by smoking or asthma. A dry cough can be a sign of a serious or life-threatening disorder. If you have difficulty breathing, chest pain, rapid heartbeat, or swollen legs or ankles, seek immediate medical care (call 911) . If your dry cough is persistent or causes you concern, see your doctor.