• Choose a category
• All
• Classic-Fiction

By Root 770 0

is that they burrow deeply into the skin of their hosts where they embed themselves (like ticks), but this is where the two parasites couldn’t be more different. Once chiggers find a suitable patch of skin (usually an epidermal pore or at the base of a hair shaft), they pierce the skin with a pair of short fangs called chelicerae. As these daggers work back and forth, muscular contractions inject saliva into the wound. This saliva contains strong digestive enzymes that produce two very different reactions in the areas adjacent to the bite. Within a few hours, the outer layer of the epidermis immediately surrounding the injection site responds to the corrosive spit by hardening into a strawlike structure called a stylostome (or histiosiphon). The stylostome, which soon extends down into the dermal layer, is formed (at least in part) by keratin, a waterproofing substance released from the hosts’ own epidermal cells. As the chigger’s saliva flows down the stylostome’s central canal, the powerful enzymes within it reach the deeper layers of the epidermis and eventually spread into the dermis. Here the enzymes liquefy the surrounding connective tissue and the contents of nearby cells. This cellular soup is the preferred diet of chiggers and although blood cells may accidentally become part of the recipe, they are not true vampires. The rudest part of the chigger’s feeding gig begins as the liquefied dermal stew is snorked up through the stylostome and into the parasite’s muscular pharynx.

Since chiggers generally feed continuously for three or four days, humans usually scratch them off long before they’re finished. Once displaced, chiggers cannot attempt to feed again and die without developing further.

Meanwhile, back at the bite site, the host’s immune system reacts to the stylostome and foreign chemicals. The resulting inflammation produces some serious and prolonged itching, which can lead to secondary infection.

In addition to misconceptions about how chiggers feed, another myth concerns ridding yourself of the pests (or at least alleviating the itching they cause) by applying clear nail polish to the irritated skin. The truth of the matter is that the chigger has probably been scratched off already and nail polish has never been renowned for its therapeutic properties. Instead, it’s recommended that the bite area be cleansed thoroughly. Following this, antihistamines and topical anesthetics can help to alleviate the itching, but even so, the welts and the urge to scratch the bites can sometimes continue for ten days or longer—basically until the stylostome has broken down and is reabsorbed by the body.

Although most chiggers do not get to complete their human meals, some chiggers lucky enough to find a nonhuman host eventually drop off (generally within three days) and burrow into the ground. There, they go through two more larval stages before a final molt results in an eight-legged adult mite.

Ticks are a much smaller group than mites (or even chiggers) and they’re divided into two superfamilies: the Ixodoidea (or hard ticks) and the Argasoidea (or soft ticks). Ticks are obligate blood feeders, and as such, their feeding habits are far more specialized than those seen in mites. Ticks feed solely on vertebrate blood, and they parasitize mammals, birds, reptiles, and amphibians, which basically means that they pester every major group except fish. Ticks are a huge problem for humans even though we are not the primary hosts of a single tick species.

Hard-bodied ticks, ixodids (which cause the most grief for humans), range from 1.7 to 6.1 millimeters in length and soft-bodied ticks can get even larger yet (3.6 to 12.7 millimeters). Amazingly, when their bodies are bloated with blood, ticks from both groups can reach lengths of between 20 and 30 millimeters.

In the United States and elsewhere, tick control has focused on hard ticks since these parasites are responsible for the transmission of eleven different diseases to human hosts (which places them second only to mosquitoes in the variety of diseases that they transmit