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Arthopods
Spiders, Mites, Chiggers, Scorpions, Ants, Bees, Wasps, Mosquitoes, and Biting Flies are all nuisances to long distance hikers, and are discussed in this chapter.

Ticks carry many debilitating diseases and are one of the most significant dangers to long distance hikers. Therefore, ticks are covered separately in the next chapter.

Anaphylaxis and Allergic Reactions
In the following sections, various arthropod species commonly found in North America are discussed. For many of these species, most hikers will only suffer temporary pain due to a sting, bites, or etcetera. For all arthropod bites, and many other wilderness occurrences, allergic reactions up to and including anaphylaxis are possible. Anaphylaxis is an allergic reaction so severe that death may result. Persons who have had severe allergic reactions before should consult with their doctors and possibly carry epinephrine and antihistamines and be trained in their use. All bug bites are important!

Wolf Spiders Lycosa
North American Wolf Spiders bites typically don't cause more than transient local pain and inflamation. They live in various ecosystems, range in size from 3-25mm, and sometimes live in underground dens.

Jumping Spider Phidippus
North American Jumping Spiders are small, furry, and aggressive. Often, the spider bites and never lets go, even if squashed. The bite may have dull, throbbing pain, irritation, and swelling.

Brown Recluse Spider Loxosceles reclusa
Brown Recluse Spider bites are justifiably infamous for killing skin at the bite, and for systemic reactions such as kidney failure, anemia, blood in urine, jaundice, etcetera. The natural range of Brown Recluse spiders is limited to the southeastern US, but some spiders have travelled in vehicles and caused bites in other US areas. Furthermore, other Sicariidae family spiders (brown and violin spiders) live elsewhere in the US. Though these other spiders are less aggressive and less venomous than the brown recluse, I myself have been bitten and lost a significant amount of skin in the chaparral backcountry of San Diego County, California. The Arizona Brown Spider, Loxosceles arizonica, also has as symptoms of a bite tissue necrosis and systemic reactions, as does L. rufescens. Brown spiders inhabit all of the southern US, coast to coast. Any spider bite should be taken seriously.

Brown Recluse Spiders are ¼ - ¾ inches, and light to dark brown or grey, black, etcetera. Sometimes a black fiddle shaped line is on the back, with the neck of the violin pointing rearward, giving nicknames like fiddleback, brown fiddler, or violin spider. Other types of spiders also have fiddle shaped markings. Though most spiders have 8 eyes, recluses and just a few others have 6. The abdomen has hairs that make it appear furry.

Brown Recluse Spiders live 2-3 years. In May, June, and July, females produce 2 or 3 egg sacs, each with ~50 eggs. It takes about a year to gow from egg to adult. These spiders can survive up to six months of drought or lack of food.

On seeing people or other potential predators, they usually jump or run away: Bites often occur when the spider is trapped between clothes and skin, and can not escape.

Brown Recluse Spiders build irregular looking, sticky webs in hidden spaces (under rocks or wood, or in cluttered gear) and walk around at night to hunt. They hunt for soft bodied insects like roaches and crickets. They may crawl under clothes or into shoes to hide from flashlights or at dawn, later leading to being trapped between the clothing and skin, and to bites.

The bite typically involves moderate pain or is not felt at all. In 37% of cases, some skin dies around the bite, and in 14% of cases, there is some systemic sickness, such as nausea, vomiting, fever, rashes, and muscle or joint pain. Rarely, blood problems, organ failures, or death occur.

When envenomated, over 2-36 hours, the bite are area becomes itchy, swollen, and painful. Necrosis, or skin death, develops over several days. The damaged skin discolors, becomes gangrenous, and eventually falls away. Healing of the skinless area may take months.

Black Widow Spider Latrodectus
There are five North American Widow Spider species, three of which are black. Bites may cause severe muscle spasms leading to muscle pain.

Widow Spiders are usually black and glossy with orange red markings. In one species, two reddish equilateral triangles join to form an hourglass shape. In others, the two triangles are separate and point at each others. These markings are on the ventral side, or under the spider. Females have bodies up to ½" and legs that span up to 2". Males are smaller but cannot bite through human skin. They range from New England down the east coast to Florida, and west to California. Though most common in the south, they live in cooler areas and up to 8,000'.

During mating, the female sometimes, but does not always, kills the male. Female Widow Spiders build an irregular looking web in a spot protected by rocks, wood, junkheaps, corners, etcetera. The female would rather run away than attack a human, except that she guards egg masses with her life, and her venom. Most bites occur between April and October, mostly to adult men, and usually on hands or forearms. Historically, when outhouses were more common, webs were built and protected there, and bites around the privates were common. Stay away from shaggy webs in spots protected by rocks, sticks, or junk, and don't use outhouses with shaggy, irregular webs.

Widow venom is strong enough to kill a 30 pound child. The initial bite causes little pain. The bite site may show minor swelling and two fang marks 1mm apart. Cramping pains radiate from the bite for 15-60 minutes, and continue for a few hours. The back, shoulder, thighs, and abdomen may cramp severely enough that the patient writhes. Pain may reccur for a few days in lesser amounts. A neurotoxic protein causes massive releases of acetylcholine and norepinephrine at synaptic junctions, causing the body wide muscle spasms. Paralysis, respiratory arrest, nausea, vomiting, headache, weakness, increased salivation, or anxiety may occur. Severe high blood pressure is possible.

Tarantula Avicularia
North American Tarantulas may have 2¾" bodies and their legs may span 5". Females may live 20 years. Their bite produces local inflamation and swelling that lasts a few hours. Some South American Tarantulas have much more toxic venoms. Beware of exotic tarantula pets or stowaways, as they may be much more dangerous than US Tarantulas. Tarantulas have urticating hairs - hairs with barbs that dig into skin and irritate. The hairs can transfer with rubbing to other skin areas, eyes, etcetera. If it seems that hairs are causing irritation, do whatever is required to keep from rubbing that area of skin elsewhere.

Scabies Mites Sarcoptes scabiei
Many people associate Scabies with poor hygeine, but anyone coming in contact with Scabies mites can be infected. People with scabies, dogs with mange, and clothing or bedding that has been in contact with scabies infected skin all can be scabies sources. Female Scabies Mites burrow in skin for 30 - 60 days and lay eggs, causing severe itching. After hatching, the larvae mature in 2 weeks, and the cycle repeats. Secondary infections from scratching are common. Creams kill the scabies, but itching may continue for weeks due to feces and secretions left in the burrows. Cream treatments must be repeated in about a week to kill hatchlings, as the cream does not kill eggs. All clothing must be washed in hot water, and all persons in contact with the must be treated, even if they don't have symptoms, or mites can reinfect the patient.

Chiggers Mites Trombicula alfreddugesi
Chiggers are red and less than .4mm long. They live in wild lands and their larvae climb up grass and bushes like ticks. Larvae drop or grab onto passing animals or hikers and bite to get a meal. They dissolve living skin and digest the fluids that ooze through. They form a tube of dried fluids and their wastes and live in it for a few days. After 3 or 4 days, they have accumulated enough food to metamorphose, and they fall off. They leave the tube, full of irritating secretions, feces, etcetera. Itching and inflammation may last for weeks. Secondary infections from scratching are common.

Bark Scorpions Centruroides exilicauda, sculpturatus
Of the ~40 species of scorpions in the US, only the Bark Scorpion has a venom potentially lethal to hikers. It occurs in the southwestern US and northwestern Mexico. It is often near trees, loose bark, and downed wood. Typically, this scorpion is 2" or less, and has a uniform color of yellow, tan, or brown. It sometimes hides in shoes, clothing, or bedding left on the ground, day or night. Hikers are stung when they pick up firewood or clothing without checking for scorpions and shaking them off. Stings of this potentially deadly scorpion can be distinguised by having the victim look away and gently tapping on the envenomation site. With this scorpion, the pain will increase dramatically, but generally not with other scorpion species. There is usually local pain, and the sting puncture may be too small to see. Pain may radiate up the affected limb, or pain may show up in unrelated body areas. Patients may feel a thick tongue or have swallowing difficulty. They may rub their eyes, nose, and ears frequently. Slurred speech, heavy salivation, blurry vision, and abnormal eye movements may occur. The extremities may jerk and shake. Fevers to 104°F (40°C) may occur.

Most scorpion stings will be locally painful for a few hours. Scorpions have 8 legs and two forward appendages with claw like pincers. They have a segmented tail which ends with a stinger: the tail is often curved up over the back. Scorpions glow under UV or black light. The flourescence may be due to beta-carboline or riboflavin. Scorpions hide in bark, under rocks, and in other places that retain humidity and comfortable temperatures. They roam around at night to hunt other arthropods. Larger scorpions sometimes kill small mice, lizards, etcetera. The scorpion typically grabs the prey with its claws and stings it, injecting neurotoxic venom. The claws pull bits off the kill, which are placed in a pre-oral cavity. Digestive juices are added, and only pre-digested liquids are then consumed, while anything remaining solid is ejected. Scorpions can live up to a year without eating. Most species reproduce sexually, but some can reproduce parthenogenetically. Mating involves a dance as the scorpions determine whether the mate is suitable and the male finds a spot on the ground where he can put a spermatophore and maneuver the female over it. Scorpions bear live young, and the young remain with the female through their first moult. Young scorpion instars look like adult scorpions.

Desert Centipedes Scolopendra polymorpha
Known variously as the Banded Desert Centipede, Tiger Centipede, Common Desert Centipede, or Sonoran Desert Centipede, this centipede often has a stripe across each of its segments. It can be 4–7 inches (10–18 cm) long. It lives in the southwestern US and innorthwestern Mexico, in dry forests, grasslands, and desert. Usually, it lives under rocks or wood, but it can burrow in some soils and rotten wood. Its bite can produce burning pain, swelling, dizzyness, anxiety, and nausea.

Some other centipedes are harmless.

Blister Beetles Meloidae
Blister Beetles are fairly common in the dry and arid southwest, but are also present in the east. There are many species of various descriptions. The beetles release Cantharidin, which causes skin blistering. Thin walled blisters up to 2 inches in diameter have occurred. The blisters form over 2-5 hours, and are not typically painful. Healing the blisters takes a week or two, during which the area should be kept bandaged, clean and dry to avoid infection. No special treatment is required.

DEET
N,N-Diethyl-m-toluamide
N,N-Diethyl-3-methylbenzamide
C₁₂H₁₇NO
DEET is a slightly yellow oil which repels arthropods such as mosquitoes, biting flies, midges, ticks, fleas, and chiggers. It is not an insecticide, and does not kill bugs. It is, by far, the most popular and effective bug repellant.

DEET was developed by the US Army following the Pacific campains with their jungle warfare. Use by the military began in 1946, and in the civilial world in 1957.

Biting insects are attracted to hikers by organic gases like octen-3-ol, lactic acid, or carbon dioxide, all given off by the hikers. There are various theories with varying amounts of evidence as to how DEET works. Historically, it was thought that DEET blocked receptors for octen-3-ol, present in breath and sweat, making it harder for insects to find people to bite. It does not appear that DEET blocks the ability to find victims via CO₂. Some evidence suggests that DEET, and other repellants such as eucalyptol, linalool, and thujone are smelled by insects, and that the scent repels the insects. Various studies of the structure of insect genes and proteins versus the structure of the repellant molecules show they are somewhat complementary. Further research may nail down the mechanisms by which repellants work and suggest better repellants.

DEET is sold in pure form and in diluted prepatations. Generally speaking, applications of 100% DEET repel insects up to 12 hours, whereas applications of diluted DEET are effective for lesser periods, well correlated with the lesser concentration. Some countries forbid sale of 100% DEET.

In some cases, DEET irritates skin. DEET should be washed off and not used again if it irritates you. It should not be applied to damaged skin, wounded areas, etcetera. In rare cases, especially with prolonged use, DEET affects the nervous system. If you develop problems when using DEET, discontinue its use. DEET inhibits the action of acetylcholinesterase, a central nervous system enzyme.

DEET repels insects when applied to the skin or clothing. However, DEET dissolves some synthetic fibers, especially the elastic components of stretch garments like Lycra, Spandex, etcetera. If you notice holes or spots with blown out elastic forming in your clothes or gear, consider being more careful when applying DEET. Carefully apply it to other areas, keeping it from that gear. DEET can dissolve paint and plastics like bottles, compasses, eyeglasses, watches, and etcetera. Make sure the cap on the DEET bottle is screwed on tight, and consider keeping the bottle in a plastic bag in case of leaks. A major leak in a pack can cause significant equipment failures, ruin food, and etcetera.

Permethrin
3-Phenoxybenzyl (1RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate
C₂₁H₂₀Cl₂O₃
Permethrin is an insecticide, acaricide, (kills insects, mites, chiggers, and ticks) typically applied to clothing.

Pyrethrum is a strong natural insecticide extracted from daisies, Crysanthemum cinerariifolium. Permethrin is a synthetic Pyrethroid.

After arthopods come in contact with Permethrin, it attacks their nervous systems, leading to death.

In studies, Permethrin was very effective, killing nearly 100% of Dermacentor occidentalis (Rocky Mountain Spotted Fever Vector) and Ixodes dammini (Lyme Vector) ticks. DEET is much less effective; typically 85%.

Permethrin should be applied to fabrics such as clothing, tents, mosquito nets, etcetera, but not directly to skin. It has low odor and is unlikely to stain cloths. It lasts through a couple of weeks, even in through heat, sun, and laundering. Application is by spraying both sides of the fabric (outdoors), just enough to moisten, and drying the garment for several hours.

Permethrin is toxic to fish and aquatic life, so avoid washing or rinsing treated clothes in water sources. Permethrin is highly toxic to cats: Keep treated fabrics from them.

Permethrin has low toxicity to humans, is poorly absorbed through skin, and is rapidly broken down in the body. However, large doses can cause nausea, headache, muscle weakness, excessive salivation, shortness of breath, and seizures. It may be a carcinogen.

Next: Tick Borne Disease

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