FACTS: There are about 3,000 species of mosquito, but culex pipiens is the most common. It is found almost all over the world, except in Antarctica.

Spanish for "little fly," mosquitoes beat their wings between 300 and 600 times per second. The unnerving sound they create differs from species to species, and listening for the right note helps male and female mosquitoes coordinate their social lives to find suitable mates!

But only female mosquitoes bite. Their eggs need the protein in blood to help develop. While culex pipiens females will happily snack on human blood, they tend to feed on birds – which implicates them in the transmission of the West Nile virus.

The actual sting of a mosquito is rarely painful, and it is seldom even detected. However, the saliva injected to stop blood from clotting provokes the aggravating skin inflammation and itching associated with a bite. Calamine lotions, and other creams, can help soothe the pain.

FACTS: Technically, all that penicillin does is to inhibit the enzyme transpeptidase in gram-positive bacteria preventing the crosslinking of the peptidoglycan polymers and impairing the generation of cellular walls. But that is enough to change the world!

It is commonly known that Scottish scientist Alexander Fleming discovered the antibacterial effects of Penicillium (from the Latin for paintbrush, Penicillium the mold produces penicillin the antibiotic agent) in 1928. He returned to his lab after a long-weekend and noticed that the growth of Staphylococcus aureus bacteria in a petri dish he had forgotten to clean was constrained.

FACTS: Pneumonia is a lung infection in which the small, air-exchanging sacs of the lungs (called alveoli) become inflamed and filled with fluid. It can come on suddenly and in serious cases it can take your breath away.

There are a number of causes of pneumonia, ranging from viruses to fungi to parasites to physical injury – though being caught in the rain without your coat is not among them. However, the most common cause of bacterial pneumonia infection is Streptococcus pneumoniae.

As the ringleader of a gang of more than 80 Pneumococcus bacteria, Streptococcus pneumoniae is such a common cause of pneumonia that a pneumonia vaccine has been developed to keep it (and 23 other of the worst kinds of Pneumococcus bacteria) at bay.

FACTS: Although there are more than 10,000 species of ants, red fire ants comprise some of the more vicious varieties.

Typically encountered when their mounds are disturbed, they can quickly swarm up an intruder’s legs in an attack coordinated by pheromones (special chemicals that provoke behavior). Although they are well-known for their tendency to bite, their bite is actually only a prelude to their sting – and it is the venom in their sting that causes the fiery, burning sensation that has earned them their notoriety.

Though they originated in South America, fire ants have natural predators in their native lands which tend to keep them in line. However, as stowaways in shipping crates, they have managed to travel the world, and are now invasive pests in many regions.

FACTS: The stomach receives, holds and partly digests food. This pouch-like organ is actually small, but as you eat the stomach wall quickly stretches to hold up to 3/4 gallon or 3 liters. It churns and mixes food with acids and enzymes. The powerful muscles lining the stomach mash food, breaking up fats and proteins. Orange juice… how about some stomach juice?! When you see or smell food, tiny stomach glands secrete gastric juice. This stomach juice is mostly hydrochloric acid with a touch of the enzyme pepsin that digests proteins. The acid activates pepsin, breaks down food, and also kills germs. Your stomach produces up to 3 liters of gastric juice every day. Mucous cells that line the stomach protect it from the acid, so that the stomach doesn’t digest itself!

FACTS: In most of the world’s dark woods and grassy plains, tiny ticks are questing in search of blood. These little vampires can be as small as pinpoints or as large as grapes – but they have an uncanny ability to sense heat and carbon dioxide, and to identify the well-travelled paths that their victims are likely to traverse. When they sense the motion of a nearby host, they drop from the tips of grasses or leaves and plunge their barbed, fang-like hypostome into their victim’s neck (or any other convenient spot) and lap up to hundreds of times their body-weight until they are sated. Or removed.