by David Moore
Manager of Technical Services and Board Certified Entomologist
with contributions by Eric Smith, PhD, BCE
This is the second blog on ticks and we will discuss the American dog and brown dog ticks. These species are typically encountered outside the home while walking in yards/parks or hiking and are important vectors of some diseases.
Ticks are not insects, but are actually arachnids (like spiders). Adults are usually greater than 1/8″ long, flattened, and oval in shape. Unlike insects, ticks do not have antenna and the adults have 8 legs instead of six.
Immature ticks, also called seed ticks, only have 3 pairs of legs. They may or may not be capable of transmitting disease organisms to humans, depending on the tick species.
Identification to species is critical because different species vector different disease causing organisms. If bitten, be sure to carefully remove the specimen, put it in rubbing alcohol, and take it with you to the doctor. A pest management professional using a microscope is often necessary to confirm species identification.
American Dog tick
Unfed adults are about 3/16″, but after they have fed on blood, they swell up to 5/8″ long and 3/8″ wide. Their color is brown with whitish to grayish markings on the area/shield just behind the mouthparts. This shield is restricted to the front half in the female, but covers most of the top in the male. Their abdomen has rectangular areas divided by grooves along its rear margin. American dog ticks are found where small and large animals frequent, readily bite humans, and vector/transmit diseases.
Brown Dog tick
Unfed adults are about 1/8″, but when engorged with blood, they swell up to 1/2″ long. Their color is reddish brown, but when engorged with blood, the engorged parts of the body change to gray-blue or olive in color. Their area just behind the mouthparts is restricted to the front half in the female, but covers most of the top in the male. Their abdomen has rectangular areas divided by grooves along its rear margin. Brown dog ticks are typically found where dogs frequent and are commonly brought into homes, but rarely bite humans and usually do not transmit disease causing organisms.
Diseases They carry
American Dog tick: This tick is an important vector of Rocky Mountain spotted fever and tularemia, and also causes tick paralysis.
Brown Dog tick: This tick will only occasionally feed on humans, and it may vector Rocky Mountain spotted fever.
Rocky Mountain spotted fever (RMSF) has thousands of cases reported each year in the United States. The typical indication of infection is fever, rash, and a history of a tick bite; other indications are malaise, severe headache, chills, and sometimes gastrointestinal symptoms of abdominal pain and diarrhea. The rash typically begins on the fifth day, starting on the extremities and then spreading to the rest of the body; there are a few cases of RMSF with no rash. It can be successfully treated about 96% of the time with one of the tetracyclines, but if left untreated, the mortality rate is about 20%.
RMSF is transmitted by the bite of an infected tick. It is generally thought that only about 1-5% ticks in a given area that can be a vector are infected.
Tick Paralysis: No disease organism is involved. It is believed that a neurotoxin produced in the tick’s ovaries causes the problem. It travels to the salivary glands and is then secreted by the tick into the host as it feeds. This usually occurs when the tick is attached in close proximity to the spine or base of the skull.
Tick Habits and Control
American Dog Tick: These ticks climb up on low-lying vegetation and grasses/weeds along trails frequented by their hosts. Here, they cling to the vegetation and wait for a host to pass to grab ahold of the host. Host animals typically travel along established trails/paths. Such areas include paths through the woods and the grass-forest transitional zone (where your grass yard meets the trees). Avoid these situations when possible.
For adequate control, you will need to take numerous items into consideration. Below are some of the most effective methods to limit exposure.
- Keep grass mowed to 3″ or less which reduces tick and rodent harborage and grass seeds (favorite food of rodents).
- If there is a fence line, remove any vegetation for 6-10″ from under the fence.
- Trim back vegetation along trails, paths, and yard edges.
- Remove debris. Moist areas attract insects (a favorite food of rodents) and provide rodent harborage.
- Removal of rodent food attractants such as bird-feeders, fruit producing shrubs, etc.
- Removal of hosts.
- This can be done by the use of rodenticides and/or traps.
- Create a 12-18″ wide vegetation-free and mulch-free zone around the perimeter or foundation of your house. Use landscape cloth under 4-6″ of crushed rock/brick or pea gravel. Keep this perimeter zone free of vegetation.
- Pesticide application. Treat likely tick habitats such as any grass-tree transitional zone/area, along paths/trails, unmaintained fence lines, etc. with appropriately labeled pesticide according to label directions. The first application should be in the early spring.
Brown Dog tick: The engorged adult female drops off the dog and climbs upwards to find a sheltered spot (wall hangings, pictures, ceiling, roof) to lay her mass of 1,000-3,000 eggs that hatch in 19-60 days. Although dogs are the preferred host, they will feed on pets and humans.
The application of residual pesticides will be required more than non-chemical measures for this tick. Remember that this tick is a pest only in areas that dogs frequent, not in the fields and woods. Removal of weeds and brush, along with properly mowed grass will reduce tick build up and the need for insecticide application. Thoroughly clean and remove all debris to reduce tick hiding places and facilitate pesticide application inside the home or kennel. Make sure you also wash any pet bedding. The dog/pet must be treated on the same day as the premises are treated. The treatment of structures and grounds must be comprehensive, so the services of a pest management professional are advised.