Protection From Blood-Feeding Arthropods
Of all the hazards, large and small, that may befall the outdoor enthusiast, perhaps the most vexatious comes from the smallest perils—blood-feeding arthropods. Mosquitoes, flies, fleas, mites, midges, chiggers, and ticks all readily bite humans (Box 39-1).
Personal Protection
Personal protection against insect bites can be achieved in three ways:
Habitat Avoidance
Avoiding infested habitats reduces the risk for being bitten.
1. Mosquitoes and other nocturnal bloodsuckers are particularly active at dusk, making this a good time to be indoors.
2. To avoid the usual resting places of biting arthropods, campgrounds should be situated in areas that are high, dry, open, and as free from vegetation as possible.
3. Areas with standing or stagnant water should be avoided, because these are ideal breeding grounds for mosquitoes.
4. Attempts should be made to avoid unnecessary use of lights, which attract many insects.
Physical Protection
1. Physical barriers can be extremely effective in preventing insect bites, by blocking arthropods’ access to the skin.
2. Long-sleeved shirts, socks, long pants, and a hat will protect all but the face, neck, and hands.
3. Tucking pants into the socks or boots makes it much more difficult for ticks or chigger mites to gain access to the skin.
4. Light-colored clothing is preferable because it makes it easier to spot ticks, and it is less attractive to mosquitoes and biting flies.
5. Ticks will find it more difficult to cling to smooth, tightly woven fabrics (e.g., nylon).
6. Loose-fitting clothing, made out of tightly woven fabric, with a tucked-in T-shirt undergarment is particularly effective at reducing bites on the upper body.
7. A light-colored, full-brimmed hat will protect the head and neck.
a. Deerflies tend to land on the hat instead of the head.
b. Blackflies and biting midges are less likely to crawl to the shaded skin beneath the brim.
8. Mesh garments or garments made of tightly woven material are available to protect against insect bites.
a. Head nets, hooded jackets, pants, and mittens are available from a number of manufacturers in a wide range of sizes and styles (Box 39-2).
b. With a mesh size of less than 0.3 mm (0.01 inch), many of these garments are woven tightly enough to exclude even biting midges and ticks.
c. As with any clothing, bending or crouching may still pull the garments close enough to the skin surface to enable insects to bite through.
d. Shannon Outdoors addresses this potential problem with a double-layered mesh that reportedly prevents mosquito penetration.
e. Although mesh garments are effective barriers against insects, some people may find them uncomfortable during vigorous activity or in hot weather.
9. Lightweight insect nets and mesh shelters are available to protect travelers sleeping indoors or in the wilderness (see Box 39-2).
Repellents
1. Development of the perfect insect repellent has been a scientific goal for years and has yet to be achieved.
2. The ideal agent would repel multiple species of biting arthropods, remain effective for at least 8 hours, cause no irritation to skin or mucous membranes, and possess no systemic toxicity, and it would be resistant to abrasion, greaseless, odorless, and not easily washed off.
3. No commercially available insect repellent meets all of these criteria.
4. Repellents do not all share a single mode of action, and different species of insects may react differently to the same repellent.
5. To be effective as an insect repellent, a chemical must be volatile enough to maintain an effective repellent vapor concentration at the skin surface, but it must not evaporate so rapidly that it quickly loses its effectiveness.
6. Multiple factors play a role in effectiveness, including concentration, frequency and uniformity of application, the user’s activity level and overall attractiveness to blood-sucking arthropods, and the number and species of the organisms trying to bite.
7. The effectiveness of any repellent is reduced by abrasion from clothing; by evaporation from and absorption into the skin surface; by its tendency to be washed off via sweat, rain, or water; and by a windy environment.
8. Each 18° F (10° C) increase in ambient temperature can lead to as much as a 50% reduction in protection time.
9. Insect repellents do not cloak the user in a chemical veil of protection; any untreated exposed skin can be readily bitten by hungry arthropods.
