AUGUST
2001

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

8-09-01

Dog Ticks Find Humans to be Suitable Hosts

They are tenacious blood-suckers that are protected with a heavy chitin covering. These creatures can withstand long periods of starvation and can regenerate lost limbs and mutilated mouthparts. They can feed on a wide range of animals, but almost nothing feeds on them.

Ticks! That scourge of the good old summertime. This is not the latest sci-fi thriller from the movie moguls of Hollywood, but one of nature's creatures.

Ticks are not insects. These animals, like insects, are classified as arthropods but are more closely related to scorpions, spiders and mites. Unlike insects, ticks do not have a head and, in the adult stage, have eight legs.

Like insects, ticks have four life stages, and they molt, or shed, their exoskeleton as they grow. The stages are egg, the six-legged larva, which is sometimes called a seed tick, the eight-legged nymph and the adult.

It is the blood-sucking habit of ticks that makes them a problem for humans. Ticks must have blood to develop. During feeding, they attach to their host. Following the blood meal, the tick drops off the host.

So how does a tick go about its life anyway? The newly hatched seed ticks climb upon grass or small trees to await the arrival of a host animal. The young tick will climb on the host and may wander around for a time before finding a place to attach. Once attached, the larvae feed and become filled with blood. When blood-filled, called "engorged," most ticks drop from the host to develop to the next stage.

Then, the tick molts into a nymph and must find another host for a second meal. Play it again, Sam! The nymph feeds and drops from the host to become an adult. Then, the adult finds another host and, after mating and a blood meal, the female drops from the host to lay eggs.

Now the good part, to the tick, that is. When a tick gets on a host and finds a suitable feeding site, it takes a firm grasp with its forelegs. The tick then drives its mouthparts through the host's skin. While feeding, the tick typically voids excretory products, which might contain pathogenic organisms that can enter the host's body through the puncture.

Ticks, as organisms, are well adapted for survival. They lay a large number of eggs-as many as 4,500 for a single female. Ticks are also able to survive for long periods without food or water. One species of tick survived for three years while confined to jars of sand.

The most common tick that humans encounter is the American dog tick. It is usually found in woods and areas of uncut vegetation. This tick will feed on a number of different animals, including dogs, cattle, horses and humans. The deer tick is also of concern since it is the primary vector of Lyme disease. It is much smaller than the dog tick and has no white markings on its back.

The best way to avoid contacting ticks is to stay away from the places where they live. If you are in tick habitats, try not to brush vegetation. Also tuck in your shirt and pull socks over pant cuffs. Application of an insect repellent to shoes and pants also helps. 

When returning from outings, it is a good idea to check yourself, children and pets for ticks. Many times you will find the tick before it has found a place to feed. If it has attached, use blunt tweezers and grasp the tick close to the skin; pull with a steady pressure. Then disinfect the bite.

Turn about is fair play. If the tick spends its entire life finding host animals, it makes sense that we can spend a little time finding the tick when it decides to make us a host! 

 

Writer: Tom Turpin
Editor: Olivia Maddox