by David Moore
Manager of Technical Services and Board Certified Entomologist
with contributions by Eric Smith, PhD, BCE
Ticks: Part 1
Please remember that this blog cannot be a substitute for the expertise and services of a pest management professional, nor can all aspects of this important topic be covered in a blog. In this first of two blogs on ticks, we’ll review the 2 species that are more commonly encountered and are of greater medical importance to humans. This first group of two species consists of the deer tick (also called the black-legged tick) and the lone star tick. These are typically encountered outside the home while walking in yards/parks or hiking, and are important transmitters of the organisms that cause diseases affecting humans. In the next blog (August), we’ll review the second group of two species (the American dog and brown dog ticks), which are commonly brought into homes on pet dogs and occasionally transmit the organisms that might cause diseases affecting humans.
RECOGNITION. Ticks are arthropods (have an exoskeleton and jointed appendages) but are not insects. Adults are usually greater than 1/8″ long, oval in shape, and are flattened. Antennae are lacking (present in insects), and they usually have 4 pairs of legs (insects have 3 pairs).
Seed ticks are immatures that have only 3 pairs of legs. They may or may not be capable of transmitting disease organisms to humans, depending on the tick species.
IDENTIFICATION. Correct identification to species is critical because different species may transmit different disease-causing organisms. If bitten, be sure to carefully remove the specimen (see below), put it in rubbing alcohol, and take it with you to the doctor. A pest management professional with a microscope is often necessary to confirm species identification.
- Black-legged or deer tick (scientific name is Ixodes scapularis).
Unengorged adults are about 1/8″ long. The female’s color is dark reddish brown except that her body’s rear half is orangish brown; males have their entire body reddish brown. The abdomen does not have small rectangular areas divided by grooves along its rear margin.
- Lone star tick (scientific name is Amblyomma americanum).
Unengorged adults are about 1/8″, but when engorged with blood, they are up to 7/16″ long and 3/8″ wide. Their color is reddish brown, but they become slate gray when engorged with blood. The female has a single whitish to silvery spot on the center of her back, whereas the male has several whitish spots along its rear margin. The abdomen has small rectangular areas divided by grooves along its rear margin.
DISEASE ORGANISMS TRANSMITTED
- Black-legged or deer tick. This tick is an important transmitter of Lyme disease (the most common animal-transmitted disease in the United States), bacteria caused human granulocytic anaplasmosis, and babesiosis (a malaria-like disease caused by a protozoan).
- Lone star tick. This tick transmits the bacteria causing tularemia, and may transmit a Lyme-like disease spirochete and/or ehrlichioses (bacteria caused disease).
- All of the above are serious human diseases and require medical attention.
LYME DISEASE. Because symptoms may or may not be evident for days to years, it is very important to capture the tick and take it with you to see a physician. The most common symptom is a spreading ring-like rash at the bite site, but it is seen in only about 70% of people bitten. So, the absence of a ringlike rash at the bite site does not mean that you are free of a Lyme disease infection.
Symptoms are usually divided into 3 stages, but they mimic several different commonly occurring diseases.
- Stage 1: Expanding rash from bite site; appears about 3-30 days after the bite.
- Ringlike/bullseye-like appearance to rash.
- One or more rash sites.
- May or may not have flu-like symptoms.
- May come and go, or persist.
- Stage 2: Complications or disorders of the heart or nervous system.
- Heart: Varying degrees of blockage of the heart muscle.
- Nervous system: Meningitis, encephalitis, facial paralysis.
- “Bells’s palsy,” other conditions involving peripheral nerves.
- Migratory pain in joints, tendons, muscles, and bones; often without joint swelling or redness.
- Stage 3: Months to years after the disease onset.
- Arthritis that appears and disappears intermittently for several years.
- Enlarged knee joints.
- Erosion of cartilage and bone.
- Note: Once bitten by a black-legged/deer tick possessing the Lyme disease spirochete, antibodies may not be produced by your body for up to 6 weeks. Therefore, it takes time to verify an infection.
AVOIDING TICK BITES
- Wear light-colored clothing to make ticks easier to see, and a long-sleeve shirt and long- legged pants are a must.
- Pull the top of your socks over the outside of the bottom of the pant legs.
- Wear a broad-rimmed hat.
- Wear permethrin-treated clothing, or treat especially your pant legs and exposed socks, top of shoes, and hat with an appropriately labeled repellent DEET containing product.
- Perform a tick check because removal within 24 hours usually prevents disease transmission. Be sure to include the back of the neck, a favorite tick attachment site.
TICK REMOVAL. Using sharp-pointed tweezers, grasp the tick as close to your skin as possible and then slowly but steadily pull the tick out. This should mean that you are pulling the tick out by grasping its mouthparts with the tweezers. If you grasp the tick by its abdomen, you may force its internal juices containing disease organisms into yourself. Put the tick into a small vial containing rubbing alcohol (kills and preserves for identification). Clean the area of the bite with rubbing alcohol and apply an anti-itch cream.
Most ticks climb up on low-lying vegetation and grasses/weeds along trails frequented by their hosts. Here, they cling to the vegetation with their hind legs and wait for a host to pass. As the host brushes against the vegetation, they grab on with their front legs.
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.
If your dog is not on a treatment regime for ticks, be selective where you walk your dog, and it is best not to take them hiking. Ticks transmit many disease-causing organisms to dogs.
CONTROL. The primary reservoir of Lyme disease in the white-footed mouse (Peromyscus leucopus), and small animals serve as hosts for the lone star tick. Our common white-tailed deer serve as the primary host for adult black-legged or deer ticks.
- Habitat modification.
- 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 habitat 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.
If you want help with your rodent control program, obtaining the proper rodent control equipment, and/or help in making appropriate pesticide applications, contact a pest management professional.
Ticks: Part 2
Please remember that this blog cannot be a substitute for the expertise and services of a pest management professional, nor can all aspects of this important topic be covered in a blog.
In this second of two blogs on ticks, we’ll discuss the second group of two species, the American dog and brown dog ticks. American dog ticks are found where small and large animals frequent, readily bite humans, and vector/transmit diseases. Brown dog ticks are found only where dogs frequent and are commonly brought into homes on pet dogs, rarely bite humans, and usually do not vector/transmit the causal organisms of diseases affecting humans.
In the July blog on ticks, the first group of two species (black-legged/deer and lone star ticks) was discussed. These species are typically encountered outside the home while walking in yards/parks or hiking and are important vectors of the causal organisms of diseases affecting humans. Also discussed in July was tick identification, avoiding tick bites, safe removal of ticks, and tick habits.
RECOGNITION. Ticks are arthropods but are not insects because they have only 2 body regions (insects have 3), lack antennae (insects have antennae), and they usually have 4 pairs of legs (insects have 3 pairs). Adults are usually oval in shape and flattened, but they swell up and become enlarged with a blood meal. Seed ticks are the first tick out of the egg and they have only 3 pairs of legs.
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 (scientific name is Dermacentor variabilis). Unengorged adults are about 3/16″, but when engorged with 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 abdominal has rectangular areas divided by grooves along its rear margin.
Brown dog tick (scientific name is Rhipicephalus sanguineus). Unengorged 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 dorsal shield (area just behind the mouthparts) is restricted to the front half in the female, but covers most of the top in the male. Their abdominal has rectangular areas divided by grooves along its rear margin.
Diseases They Vector
- 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). There are about 2,000 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 myalgias, 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. Of the ticks that vector the disease, generally only about 1-5% of such ticks in a given area 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.
Habits and Control
- American dog tick. Follow the habits and control information given in the July blog.
- Brown dog tick.
- The problem is that 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 other mammals including domestic animals 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.
- Because these ticks can drop from any dog any time, leash laws are helpful as is a coordinated community control effort.
- Inside the home or kennel, thoroughly clean and remove all debris to reduce tick hiding places and facilitate pesticide application. Wash 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.