Blood Feeder Identification Guide
Blood Feeders-General
Blood-feeding arthropods are of great concern to the public not only because of their annoying and often painful bites but more importantly because many are vectors of pathogens that cause diseases affecting humans and domestic animals.
Human Lice
Pest control operators are frequently asked either by individuals or organizations, to apply insecticides to surfaces to control human lice outbreaks. Accordingly, there seems to be some controversy over the technician’s role in these cases. Should technicians treat premises for lice infestations? And if not, why? These are questions that will be addressed in this Technical Release. First, it is important to understand the characteristics of these ectoparasite insects and their medical importance.
IMPORTANCE
The body louse and head louse have been implicated in the transmission of human diseases, particularly typhus, relapsing fever, and trench fever. Historians have noted that outbreaks of typhus have influenced the outcomes of battles and wars. Outbreaks of these diseases are often associated with war or natural disasters. Pediculosis, the infestation of lice, is not a new problem. The infestation may involve not only one but on occasion all three types of lice. Discomforts such as itching and scratching may result from a louse infestation. And when excessive scratching occurs it can lead to a secondary infection. However, infested individuals are sometimes without symptoms and may not experience any itching or scratching.
TYPES AND IDENTIFICATION
The lice that infest humans are the sucking lice, belonging to the insect order, Anoplura. They are usually, but not always, found on a certain part of the body and are named according to the region of the body they infest and/or their physical appearance. The three species infesting humans are:
- Head Louse, Pediculus humanus capitis. Adults are elongate, usually 1/6-1/8 inch (1.0-2.0 mm) long, reddish-brown in color with dark margins. Their legs are equal in length and each one has a claw to grasp the hair. Thus, head lice cannot hop, jump, or fly, they can only crawl. The immature forms (nymphs) are similar in appearance to the adults but are much smaller. The adult female is larger than the male. She glues her grayish-white eggs (nits) to the hair shaft. Nits can be found anywhere on the head, including the nape of the neck, eyebrows, eyelashes, behind the ears, and at the crown.
- Body Louse, Pediculus humanus corporis. The major difference between this louse and the head louse is that the body louse is larger than the head louse, averaging 1/8-7/32 inch (2.0-4.0 mm) in size and do not have the dark margins typical of the head louse. Most importantly, these lice live on a person’s clothing, however, they return to the body to feed. Unlike head lice, a body louse infestation may reflect poor hygiene.
- Crab Louse, Pthirus pubis. The smallest of the three lice is usually 1/16 inch or less (0.8-1.2 mm) in length. It is easy to recognize the distinctive body shape and legs which give this insect its common name. The legs are unequal in length and specially modified for grasping hair. The crab louse is more sedentary in nature than the other two species and prefers an area where the hair is more widely spaced; i.e., pubic areas, although they have been found in moustaches, eyebrows, and beards. However, the latter examples are rare. In some situations, children are found to have infestations in their eyebrows. Infestations of these lice can cause the skin of the infested area to develop purple pigmentation.
As mentioned earlier, all three species need human blood to survive and must stay close to the host, either on the body or in the case of the body louse-to the clothing of the infected individual. There is controversy as to how long a louse can live off the host, however, it is currently believed less than 24 hours, depending on environmental conditions such as relative humidity and temperature. Egg hatch generally occurs within 7-10 days, depending on environmental conditions.
TRANSMISSION
The most prevalent means of contracting a louse infestation is person-to-person contact, but they can also be indirectly transmitted by combs, brushes, towels, hats, upholstered furniture, etc. On the other hand, crab louse infestations are almost always obtained through intimate contact. Children may pick up infestations from their parents, older siblings, and other children. The practice of sharing combs and brushes should be discouraged to avoid the transmission of head lice. Crowded conditions can cause infestations to spread and increase rapidly. Unsanitary conditions often cause a body louse infestation to go unnoticed.
These insects, like most other ectoparasites, cannot survive on alternate hosts. Therefore, dogs, cats, and other animals do not need to be treated for human lice.
CONTROL AND THE TECHNICIAN
Insecticidal premise treatments are not necessary since these insects cannot survive for long periods away from the human host. Although nits can survive longer than adult lice, they need moderate temperatures to hatch and must locate a host immediately upon hatching to feed, or they will die.
Body louse controls include improved individual hygiene and laundering of the individual’s clothing and bedding. All family members and other persons who may have come in recent contact with the infected individual should be examined closely for louse infestation by a physician or public health professional who generally recommends the local application of pediculicides to the areas of infestation.
The Center for Disease Control states that epidemiological studies indicate that most transmissions of head lice occur by direct person-to-person contact and not by the person-environment-person route. For this reason, the home or school environment should not be treated with insecticides. Vacuuming will remove fallen hairs with attached nits from furniture, mattresses, rugs, stuffed animals, toys, and car seats. Frequent and vigorous vacuuming should be encouraged. Laundering of hats and similar head attire will remove nits.
The pest control industry receives numerous requests for assistance to control lice. The professional response should include accurate information on the life cycle of the louse and helpful guidance on prevention and management procedures. And, most importantly, management does not include applications of insecticides to the premises.
For additional resources and information on head lice management, contact the National Pediculosis Association (NPA), a nonprofit health organization dealing exclusively with this problem. The NPA sponsors National Pediculosis Prevention Month as a back-to-school prevention campaign each September and offers for purchase a recently published book entitled, Keep Your Wits Not Your Nits. To contact NPA, write P. O. Box 149, Newton, MA 02161; or call 617/449-NITS.
The information contained in NPCA’s technical publications should not be construed as standards of the Association. The information describes methods and procedures that should be regarded as recommendations or optional guidelines. Each company or person using or distributing this publication is responsible for ensuring its accuracy and applicability all the time and under the circumstances used or distributed. This release is subject to periodic review and update by NPCA technical staff. This release supersedes ESPC 037113, 6/10/77.
Fleas & Ticks
Blood-feeding arthropods are of great concern to the public not only because of their annoying and often painful bites but more importantly because many are vectors of pathogens.
- More than 2,400 species exist worldwide.
- Attracted to animals by body heat, movement and the carbon dioxide that animals exhale.
- Adults feed on blood; larvae feed on organic debris.
- Found on cats and dogs year-round, but most common during warm and humid weather.
- Life span on dogs is typically more than 100 days — enough time for a pair of fleas and their descendants to produce millions of offspring. Under ideal conditions, assuming no mortality, a pair of fleas has the potential to produce more than 20 trillion descendants in one year.
- Found on opossums, rats, other rodents and humans.
- Can transmit tapeworms from dogs and rodents to other animals and humans.
- Can jump up to 150 times the length of their body.
- Transmit several major human diseases including plague, murine typhus, Bartonellosis and tapeworms.
Pest Facts: Blacklegged (Deer) Ticks
Description
The black-legged tick is named for its dark legs, which are a contrast to its pale body. Blacklegged ticks are sometimes called deer ticks.
Pest Facts:
Color: Dark brown to black body
Legs: Eight
Shape: Flat; broad oval
Size: 1/8 inches
Antennae: No
Flying: No
Region: All 50 States
Habits: These ticks like to feed on the blood of white-tailed deer, which is why they are sometimes called deer ticks.
Habitat: Blacklegged ticks prefer to hide in grass and shrubs.
Threats: Blacklegged (deer) ticks can spread Lyme Disease.
Prevention: When in an area where ticks are common, wear long-sleeved shirts and pants, preferably light-colored so ticks will be easy to detect. Tuck pants into socks. Use a tick repellent. When you return indoors, inspect clothing and skin thoroughly for ticks, including the head. Wash clothes immediately.
Pest Facts: Mosquitoes
Description
One of the best-known summer pests, mosquitoes breed in stagnant water or soft soil and can develop from egg to adult in 10 to 14 days.
Pest Facts:
Color: Varies; Pale brown with whitish stripes across abdomen
Legs: Six
Shape: Narrow Oval
Size: 1/4-3/8 inches
Antennae: Yes
Flying: Yes
Region: All 50 States
- Can transmit West Nile encephalitis, a sometimes fatal inflammation of the brain.
- Acquire the West Nile Virus from infected birds.
- Breed in stagnant or putrid water. Mosquitoes are unlikely to breed in clear, clean water such as a well maintained swimming pool.
- Are effectively repelled by products containing DEET (N,N-diethyl-meta-toluamide).
Habits: Female mosquitoes suck our blood. Male mosquitoes feed on plant nectars. They can develop from egg to adult in 10 to 14 days. They are most active from dusk to dawn and will fly up to 14 miles for a blood meal.
Habitat: Mosquitoes breed in stagnant water sources such as storm drains, old tires, children’s wading pools, and birdbaths.
Threats: Mosquitoes are well-known to spread diseases such as West Nile Virus, malaria, and dengue fever.
Prevention: Eliminate or reduce mosquito breeding sites by replacing all standing water at least once a week. This includes birdbaths, ponds, and unfiltered pools. Remove unneeded vegetation or trash from around any standing water sources that cannot be changed, dumped, or removed. Introduce mosquito-eating fish such as gambusia, green sunfish, bluegills, and minnows to standing water. Screen windows, doors, and other openings with mesh. Avoid going outdoors when and where mosquitoes are most active: during dusk or dawn. Use insect repellent containing DEET on exposed skin whenever or wherever mosquitoes are likely to bite.