In the animal kingdom there are many creatures that can bite or sting humans, pets, livestock or wildlife. Many of these bites or stings can cause pain, death or reactions to our systems that can be mild to extreme. This article cannot cover all scenarios, all bites, all stings delivered by every animal or insect on the planet. It will, however, attempt to describe the different problems encountered by humans and domestic animals that are caused by insects, reptiles and others.
Not all insects, reptiles, animals cause pain, sickness, allergic reactions or death. Even of those creatures that have the ability to bite or sting, not all have the ability to puncture human skin. All spiders can deliver toxins but very few can actually deliver these toxins deep enough through human skin to actually cause sickness or death. (See Black Widow Spiders, Hobo Spider, Brown Recluse Spiders.)
Of those that can puncture or cut human skin, most are defending themselves or are looking for a blood meal. Chiggers, mosquitoes, fleas and ticks are examples of those that have mouthparts that enable them to puncture skin for feeding on blood. Horse Flies and Deer flies are examples of insects that have mouthparts that actually cut skin (instead of puncturing) to get to their food, which is blood.

Among the creatures discussed will be spiders, snakes, biting flies, mosquitoes, fireants, bees, wasps, hornets, centipedes, scorpions, chiggers and others. Whether the pain or discomfort is caused by teeth, stingers or even prickly body parts, no one enjoys the self defense mechanisms and feeding habits of pests found in fields and around the home.
Arthropods are insects that live primarily on land and have six legs. They represent about three-fourths of known animal life. The actual number of living species could be as high as 10 million.
The orders that contain the greatest numbers of species are Coleoptera (beetles), Lepidoptera (butterflies and moths), Hymenoptera (ants, bees, wasps), and Diptera (true flies).
First, the creatures that are not insects: scorpions, snakes. Both scorpions and snakes deliver painful (sometimes lethal) doses of venom. The venom has a two-fold purpose: to aid in the capture of prey and as a self defense mechanism.
The venom of snakes is a complex subject due to the different types of snakes and the makeup of their different venoms. The basics of poisonous snakes, pictures of poisonous snakes, their range and description are covered in the Poisonous Snakes section.
Scorpions have a true stinger located at the end of their tail. Many people are intimidated by the "claws" of the scorpion but the pain delivered by this animal only comes from its stinger. This stinger is primarily used to paralyze prey but when cornered, the scorpion will defend itself. In the United States, most scorpion stings are not lethal to humans. The severity and reactions to the sting vary with the size, species and health of the scorpion as well as the age and health of the person stung.
Scorpions feed on spiders, small insects, centipedes, other scorpions or earthworms which technically makes them welcome around homes. However, most people have a fear of scorpions and do not feel comfortable having them as house guests. Parents of small children do not relish the idea of an inquisitive child trying to play with this animal as its sting will in most cases have the impact or feel of a wasp sting. Small children and the elderly are more likely to have the worst results or reaction to the sting of a scorpion. More information about scorpions and their control (if they invade your home) can be seen on the Scorpions web page.

Centipede Sting, Millipedes

There are many stories about the bite or sting of Centipedes and Millipedes, many of them are not based on fact but, rather, fiction.
Millipedes do not have a stinger but there are certain species that can cause irritation to humans due to certain chemicals released when the bug is crushed.
Centipedes can vary in size and severity of sting, based on the particular species, size and health of each centipede encountered. Centipede venom is injected by a pair of modified legs that are located near the head. These hollow appendages (which deliver venom into victim or attacker) are not always visible unless the centipede is intent on using them. Reports vary but deaths caused directly from the sting of a centipede are extremely rare. The sting of a centipede can be quite painful, comparable to the sting of a hornet.
Centipedes do not search out and attack humans. Painful encounters with this multi-legged creature occur when it is cornered, disturbed or otherwise mishandled. Most reports of centipede stings seem to stem from inquisitive children attempting to pick up the bug or an adult simply touching it by accident. Many cases reported are simply stories of someone rolling over on top of the centipede in bed. Waking up to the painful sting of a centipede is as almost as frightening as it is painful. Numerous people have compared the sensation to being burned by a lit cigar are being stung by a large hornet.

Next in our group of bites and stings are spiders. The bite of a spider varies with the species. All spiders have venom. Black Widow Spiders and Brown Recluse Spiders are known and feared because their bites can cause serious or uncomfortable reactions. Their venom differ (see more about Black Widow Spiders, Brown Recluse Spiders and Brown Recluse Bites) but these spiders have one important thing in common: their bites are angled in such a way as to puncture human skin and to deliver their toxins into our system. Not many spiders can actually deliver their venom into humans. Many people fear spiders; some of these fears are founded and some are not. Spiders (like scorpions) are predators that keep insect populations in check, making them a part of nature's pest control.
There can be many reasons for people to not want spiders in their home. A fear of spiders or concern for children and the elderly are two of the most popular reasons why people search for ways to eliminate spiders from homes, schools, nursing homes and other human dwellings.

Hymenoptera is a group that includes insects with true stingers. Bees, Wasps, Yellow jackets, Hornets, Ants, Fireants belong to this group.
The fireant is an insect that bites and stings but the bite itself is not what inflicts pain. This social insect will (when disturbed or when its colony is disturbed) emits powerful pheromones that attract and alarm other members of the colony. These pheromones call the colony members to the attack. Once the fireant locates and contacts what it perceives to be its enemy, it first bites its victim or attacker. This bite is not intended for use as pain inflicting device but rather as a means to hold on so that it can use its stinger. The fireants that cover your feet, ankles and legs after you step on their mound are all female ants. The stinger is actually a modified ovipositor which (by definition) is an egg laying apparatus of a female insect.
After attaching itself to your skin with its teeth, the fireant can better deliver its painful sting. The ant swivels around as it holds on, delivering multiple stings in a circular pattern. The fireant stinger is not barbed (as is the stinger of the honey bee) and does not remain impaled in the skin. This allows each fireant to deliver many stings without causing its own death. (Insects with a barbed stinger can only sting one time, as the barbs cause the stinger to remain in its victim, also causing death in the insect delivering the sting.)
Another difference between the sting of the fireant and the sting of other insects lies in the substance injected by its stinger. Wasps, bees, yellow jackets and other stinging insects deliver certain proteins into our skin that cause the painful, burning sensation associated with their stings. The fireant sting, however, does not contain this type of material. The venom of fireants contains alkaloids combined with relatively small amounts of protein. This venom is very effective for killing insects and also kills certain fungi and bacteria.
The sting of a single fireant is not nearly as painful as a single sting from a wasp or centipede. The pain and danger lies in the multiple stings delivered by a single ant and (most important) the fact that fireants rarely attack alone. Their powerful pheromones tell their colony members that help is needed. The real pain of fireants comes from the combination of hundreds of angry insects - and each one stings numerous times.

Bees, Wasps, Yellowjackets

Other stinging insects such as bees (female carpenter bees, bumble bees), wasps, yellow jackets can also cause a great deal of pain but these stings can be painful if even a single sting is inflicted on its victim. Mud Daubers are stinging wasps but are not social insects as are honey bees, yellowjackets.
Bees, wasps and hornets belong to the Family Vespidae.
The most dangerous encounter would be the attack of multiple stings from these insects. Being social, these insects will attack as a group if they sense that their colony is under attack. Wasps and yellowjackets not only attack as a group but (just like the fireant) each individual can and will continue to sting until it senses that the perceived or real danger has passed.
The barbed stinger of the honey bee prevents the bee from stinging more than once. After stinging its victim (or attacker) the honey bee loses its stinger. It flies away to die later on. The real danger lies in the pheromones released by alarmed honey bees which attracts colony members to the attack.
Much has been reported on the Africanized Honey Bee. The major note to be made about this particular species is its aggressiveness. The Africanized Honey Bee has the same venom in its sting as the more passive (although painful) European bee. The danger lies in how many bees respond to the danger pheromones and how persistent the insect is in defending against its enemies. On average, the domestic honey bee will defend its nest in an area which extends as far as 150 feet from the nest. The Africanized honey bee will defend an area extending more than 400 feet from the bee's nest.

Diptera include Biting Flies (horse fly, deer fly, stable fly, etc.), mosquitoes. Insects in this group do not sting but their bite can be painful or irritating. This group is divided between those that cut skin and those that burrow or puncture skin. These cutting, burrowing, puncturing actions are possible because of the specialized mouthparts of each bug and are necessary for one important part of their lives: feeding on the blood of animals. The female mosquito and the female biting fly are both responsible for bites as they have the need for blood meals. (Male biting flies are more likely to spend their time gathering pollen, nectar and do not need blood in their diet for reproduction or survival.)
Chiggers (the larval stage of the Harvest Mite) can actually burrow into the skin of its host - but it does not remain there. The chigger will burrow into the skin just long enough to get the blood meal it needs to survive and to continue to grow into its final adult stage as a Harvest Mite. Many people still believe that the burrowing insect remains in their skin after feeding. This belief can be derived from the irritation caused by the intruding insect.
There are substances in the saliva of the chigger that first desensitize the area so that the host does not immediately react to the presence of the blood feeding insect. There are also substances in the chiggers saliva that prevent the wound (caused by its feeding habit) from healing too quickly, thus insuring that the chigger is not trapped by coagulating blood. These substances are very irritating to humans.
The desensitizer is very powerful, lasting for several hours. For this reason, we do not feel the effects for up to 48 hours after being exposed to chiggers. The redness and irritation associated with chiggers has given these insects the nickname of Red Bugs. To determine where you were when you encountered chiggers, count back 24 to 48 hours from when you began exhibiting irritating signs of their "bite." For more about this irritating little insect and how to eliminate them from your property, go to the Chiggers Information article.
Mosquitoes have a mouthpart that enables them to puncture the skin of people and animals. In this manner they can obtain the blood meal they need to reproduce and to survive. Mosquitoes, fleas and chiggers all have substances in their saliva that refine this feeding to protect them from their hosts, substances that also cause irritations to our skin. Mosquitoes, however, pose far more possible hazards to humans and pets than most insects.
As these insect flies from one host to another, it can easily spread certain diseases. The most notable are malaria and West Nile virus.
Mosquito Control article.
Female biting flies require blood meals to survive and reproduce but their mouthparts are different from the flea or mosquito. Rather than puncturing the skin to siphon a meal of blood, this group of insects actually cut or saw the skin to expose the blood needed by the biting fly. This sawing and cutting action brings immediate pain to the victim. Mosquitoes can be repelled from feeding on humans by a product recommended by the CDC called DEET. Biting flies, however, are rarely ever repelled by DEET when it is used alone. For more information:
Biting Flies (Deer Fly, Horse Fly and others) Mosquitoes
Repelling Mosquitoes Repelling Biting Flies Mosquito Control Fly Control

The bite of a tick does not inflict pain as does the bite or sting of most insects discussed on this page but they are listed here for their importance in health issues of people, pets and livestock as well as importance as a general household pest.
Ticks are arachnids that attach themselves to a host or hosts in order to obtain a blood meal. These blood meals are not only for basic nutrition but are absolutely necessary in order for female ticks to produce and lay her eggs. Varying among different species (which are broken down into two basic groups: Hard Ticks and Soft Ticks) the female might need multiple blood meals or a single blood meal to further along her egg laying cycle. Immature ticks (called nymphs) also need blood to further their development from one instar (life stage) to another. Immature ticks can go without food for much longer periods than can adult ticks. This is an important factor to remember when dealing with an indoor tick infestation.
Ticks are important disease carriers, the most notable being Lyme Disease. For more information on ticks and diseases, basic tick biology and information on how to eliminate ticks from your home, property or pets, go to the Tick Information web page. If you only need information on how to control or prevent a tick infestation, go to the Tick Elimination page.