Photo: Jim Occi, BugPics, Bugwood.org blacklegged tick Ixodes scapularis
The blacklegged tick (aka, deer tick), Ixodes scapularis, has now been identified in all 67 of Pennsylvania’s counties. For many years, western Pennsylvania has experienced fewer problems when compared to the eastern part of the state. That is no longer the case.
People who work outdoors, including arborists, landscape professionals, and nursery growers are thus at risk for contracting this often-misdiagnosed disease. While public officials warn residents to avoid tick-prone areas, that is not option for those who work in such areas. Fortunately, there are steps you can take to minimize the risk of contracting Lyme disease for yourself and your customers.
Know The Enemy
The blacklegged tick has a two-year life cycle, starting with engorged females laying eggs in mid-to late spring, usually near where they have detached from their hosts. Adults die after mating and laying eggs. The six-legged larvae hatch in summer and first attach to small mammals such as mice and chipmunks or birds to feed. Larval activity peaks in mid- to late summer. Newly hatched larvae do not carry the causal organism for Lyme disease (or other tick-borne pathogens), but become carriers after they feed on infected mice, chipmunks or birds. Engorged larvae drop off to the ground where they overwinter and molt into the nymph stage.
The eight-legged nymphs become active in the spring of the following year, with peak activity occurring from May through July, depending on environmental conditions. If the nymphs fed on a host infected with the Lyme disease causal organism as larvae, they may have the potential to transmit the disease to humans, or domestic or wild animals. Nymphs also attach to small mammals or birds, and they molt into adults after feeding. Nymphs are often the life stage that transmits Lyme disease to humans. Because nymphs are so small - maybe the size of a poppy seed - it is hard to see and remove them.
Nymphs molt into adults in the fall, when they seek out medium to large mammals, such as white-tailed deer, as hosts. While blacklegged tick adults may be infected with the Lyme disease causal organism, they are more likely to be seen and removed from people or companion animals before they have a chance to feed. Adult blacklegged ticks remain active in fall and warm winter days into the following spring. The blacklegged tick is often not killed by cold, winter weather, especially when there is an insulating snow pack on the ground.
The white-footed mouse (Peromycus leucopus) is an important host for both the larval and nymphal stages of the blacklegged tick, and is also a primary host for the bacterium that causes Lyme disease, Borrelia burgdorferi. They also are important hosts for other tick-borne diseases such as babesiosis and ehrlichiosis. Deer are not hosts for the Lyme disease causal organism, but they do provide a means of transport for the adult, reproductive stage of blacklegged ticks.
The blacklegged tick is most abundant in densely wooded areas and the edges of woods; ornamental plantings and mown lawns are less attractive to them, except where they abut the woods. Blacklegged ticks prefer dense cover that maintains a humid environment.
Always wear long pants, socks, and close-toed shoes. If you can, wear light-colored clothing so that even small life stages can be seen more easily and removed promptly. Have crew members check each other's backs for ticks. If you are working on tick-prone properties, tuck your pants into your socks to make it harder for them to get under your clothing. I know it looks nerdy, but looking nerdy beats contracting Lyme disease any day of the week. The use of tick repellents that contain DEET or permethrin, when used according to label directions, may provide protection.
If a tick attaches to you, remove it carefully so as to avoid squeezing its stomach contents into you. Fine-tipped tweezers work well, as do any number of tick pullers available on the market. Grasp the tick as close to the skin as possible and pull upward slowly with a steady, even pressure. You may be surprised at how much force it takes to dislodge such a small creature. See your family physician as soon as possible; most will start you on a preventative course of antibiotics to minimize the chance of contracting Lyme disease.
Tick Management as a Niche Service
There are a number of landscape pest management practices that can make your customers' yards less suitable habitat for blacklegged ticks. If you manage large residential properties, consider managing the portion of the landscape the family uses the most to minimize blacklegged tick habitat, including walkways, patios, play areas, gardens, and service areas (sheds, trash cans, etc.).
- Regular clean up of brush, fallen leaves and removal of weeds and brush at woodland edges.
- Keep grass mowed regularly throughout the growing season.
- Restrict the use of dense groundcovers in areas heavily used by family members and pets because they maintain a humid environment that blacklegged ticks prefer.
- Discourage rodent activity by keeping grass, brush and weeds trimmed, cleaning up leaf piles, and sealing stone walls.
- Exclude deer through the use of fencing and deer-resistant plantings. Rutgers University lists landscape plants by how likely or unlikely they are to be browsed by Bambi. While deer will eat almost anything when they are hungry, it is a good place to start. Excluding deer may reduce the number of egg-laying adult blacklegged ticks brought into customers' yards.
- Discourage customers from feeding birds near the areas family members use the most because bird feeders attract deer and white-footed mice, especially in winter when other food sources are scarce.
- Suggest that customers locate children's play sets and sand boxes away from woodland edges. Use hardwood mulch around these items rather than grass or other vegetation.
- Create borders of wood chips or gravel at woodland edges and around stone walls to make them less attractive to rodents and blacklegged ticks.
- Do not sacrifice good plant health, but limb up trees and thin their crowns to allow more sun in and to reduce humidity, which makes an area less attractive to blacklegged ticks.
- On residential properties known to have blacklegged tick issues, consider perimeter sprays of registered acaracide formulations applied according to all specimen label directions. Active ingredients for such applications include registered formulations that contain bifenthrin, cyfluthrin, lambda-cyhalothrin or permethrin.