Bed Bugs - Biology and Control
Michael Waldvogel and Charles Apperson, Entomology Extension Specialists
|Insect Note - ENT/rsc-#31|
Bed bugs have become a common problem across the country infestations showing up in residences, hotels, college campuses and other places. Many people associate bed bugs with unsanitary conditions, as often is the case with pests such as cockroaches. However, bed bug infestations occur across the spectrum of social and economic settings. Experts have speculated that the increase is more likely due to a number of factors such as to be more related to increased travel & tourism, changes in tactics used for controlling pests such as cockroaches, and an increasing resistance by bed bugs to the most commonly used insecticides.
Our primary concern is with the “common” bed bug, Cimex lectularius. Another species in the bed bug family (Cimicidae), Cimex hemipterus, is usually found in more tropical areas and may show up particularly for people engaged in international travel. A number of other species are more frequently associated with birds and bats but on occasion invade homes.
Bed bugs adults are reddish-brown, oval, flattened insects about 3/16" long and up 1/8" wide. Engorged (blood-fed) adults are swollen and dull red. Though wingless, adult bed bugs do have small wing pads. The dark-colored eyes stand out and the sides of the collar-like pronotum curve slightly around the head and is covered with long hairs. The nymphs (immatures) resemble the adult but are smaller in size. Newly hatched nymphs are almost colorless whereas engorged (blood-fed) nymphs are reddish and swollen. Bed bug eggs are white, oval egg is about 1 mm long.
Life Cycle and Habits
Although humans are the preferred host, bed bugs feed on many warm-blooded animals including rats, mice, dogs, cats, poultry and other birds. Bats, swallows and chimney swifts may serve as hosts and may be responsible for causing infestations in or around buildings but they are more typically fed upon by other species in those situations.
There has been no scientifically-based evidence showing that bed bugs transmit diseases. Our major concern is more about the affect of their feeding. Bed bugs do not bore into the skin.They insert their mouthparts into the host's skin and suck out blood. As bed bugs feed, they inject saliva which may produces an allergic reaction that often causes slightly delayed swelling, itching, and irritation that can persist for a week or more. Large infestations of bed bugs may have a noticeable "sweet" odor.
Bed bugs can feed and breed year round under favorable conditions. They typically hide during the day in mattresses or cracks and crevices. The picture above shows a bed bug and fecal stains in a mattress seam. Under favorable conditions, each female lays 200 to 500 eggs. When the insects feed regularly, eggs are laid in batches of 10 to 50 at 3 to 15-day intervals. Maximum egg laying occurs when the temperature is above 70°F (21°C). Eggs are typically not deposited when temperatures drop below 50°F (10°C). The eggs are coated with a sticky substance that dries after the egg is deposited and causes the eggs to adhere to the object on which they were deposited. Eggs and the eggshells are found, singly or in clusters, in or near the crevices bed bugs are hiding. At temperatures above 21°C (70°F), eggs hatch in about 10 days. At lower temperatures, hatching may take as long as 28 days.
Newly hatched bugs feed at
the first opportunity. They molt five times before reaching maturity
and require at least one blood meal between each molt. Immature stages
can survive more than two months without feeding; however, most
nymphs usually develop into adults within 2 to 6 weeks. Indoors, three or four annual
generations may be produced and you will find all stages of bed bugs in an established infestations. Bed bug adults
can survive up to a year or more without feeding, which means that infestations may continue to survive even if a house was left vacant for several months.
Bed bugs cannot fly or jump and do not normally crawl long distances. Their primary means of dispersal is through human activity, i.e., people move them from one place to another in luggage, laundry, etc. Animals, particularly birds and bat, may be involved in bed/bat bug dispersal. Piles of cast nymphal skins often accumulate in bed bug hiding places. The picture at the right shows piles of shed skins at the base of bed headboard.
Eliminating Bed Bugs
Step One - confirm that you do have bed bugs. Bed bug bites often leave a reddish slightly swollen welt that can resemble a mosquito bite but typically last longer. Some people do not react as severely. The bites may be in a pattern of 3-4 in a row (depending on the number of bed bugs present and how a person lies on a mattress). However, a bed bug problem cannot be reliably identified solely on the basis of welts or other seemingly insect-related bite marks. It is critical to find actual evidence of the bed bugs: actual insects, shed skins, fecal spots, etc. as shown in the pictures above.
Step Two - Locate all of their hiding places:
Step Three - Control
Many pest control services now recommend (or require) that treated mattresses and box springs be placed inside sealable casements (shown at right) that prevent bed bugs from escaping the treatment and also keep other bed bugs from re-infesting the items. When treating furniture for bed bugs make sure you use only products that are labeled for application to these items. You can click on the following links for examples of pesticides available to the general public and pest management professionals. Always read the label and follow directions and safety precautions. Here are some important reminders about using pesticides:
For extreme or difficult infestations, fumigation may be used (picture at right). Fumigation is not the same as using a "fogger" (total release aerosol). Foggers are not effective in eliminating bed bug infestations. Fumigation uses a toxic gas and you must either seal the entire house (or entire apartment building) or place furniture and other items into an isolated container (e.g., a panel truck or steel storage container) and sealed for treatment. Fumigating an entire house (or apartment) may require that the entire building be covered with a tarpaulin (or completely sealed) in order to treat it. Fumigation will kill all of the bed bugs and is an alternative to other insecticide applications if an entire house is infested; however, it leaves no residual (killing) insecticide.
Some people prefer to dispose of infested mattresses and other furniture rather than deal with treating them. It is important to dispose of these items properly. First, you must wrap the items in plastic sheeting before carrying it outdoors so you bed bugs do not crawl onto you or drop off indoors unseen which may further spread the infestation. Second, whether you live in a house or an apartment building, never put infested furniture at the curb or next to a dumpster (if allowed) without first rendering it unusable (e.g., cutting the fabric). Otherwise, someone may take the items which only spreads the bed bug problem further. If you replace infested items, do not bring them into the house until you know you have the problem under control or else these new items will become infested. Clothing and some other items that are infested (or suspected of being infested) can be washed in hot water (or follow the tag on the article); however, washing alone will not always kill bed bugs and their eggs. Heat (drying in clothes dryer on ‘High’ for about 30 miinutes or until dry) will kill them. Other items may require dry cleaning which can become an expensive option. Simply isolating clothing or other infested items in trash bags may work but remember that bed bugs can survive for more than six months without feeding.
Physical barriers such as double-sided tape on the legs of beds can help keep bed bugs from crawling onto the frame. There are also commercial traps available online that claim to stop bed bugs from migrating onto beds from surrounding areas. However, none of these barriers will help unless you keep bedspreads, blankets, etc. from touching the floor and providing bed bugs with an "alternate route" onto the bed. Keep in mind that these physical barriers help but they are not a fix for bed bug infestation.
Many pest control companies now offer freezing and/or steam treatments for some types of infested furniture such as mattresses and box springs. Another control method that has proven to be effective is heat treatment. This requires that all of the suspected items or in many cases the entire living area be sealed and heated for several hours to >120°F (picture at right). Heat treatments are not simply a matter of raising the air temperature. The heated air must penetrate all areas of the room/house in order to kill bed bugs that are hiding in household articles, in furniture or clothing, or even in walls. Excessive heating can damage furniture, electronics, and other items and may even start a fire if not done properly
The best approach to dealing with bed bugs combines both chemical and non-chemical methods in order to provide a greater likelihood of control. However, even with the use of fumigation, heat and/or conventional insecticides, there is currently no treatment method that can prevent bed bugs from being reintroduced into and reinfesting a home or any other building..
Protect Yourself From Infestations
Information and the bed bug image used in this publication were taken
from Insects and Related
Pests of Man and Animals
|Pest information and control
recommendations presented here were developed for North Carolina and may
not be appropriate for other states or regions. Any recommendations for
the use of chemicals are included solely as a convenience to the reader
and do not imply that insecticides are necessarily the sole or most appropriate
method of control. Any mention of brand names or listing of commercial
products or services in the publication does not imply endorsements by
North Carolina Cooperative Extension nor discrimination against similar
products or services. All recommendations for pesticide use were legal
at the time of publication, but the status of pesticide registrations
and use patterns are subject to change by actions of state and federal
regulatory agencies. Individuals who use chemicals are responsible for
using these products according to the regulations in their state and to
the guidelines on the product label. Before applying any chemical, always
obtain current information about its use and read the product label carefully.
For assistance, contact the Cooperative
Extension Center in your county.
Distributed in furtherance of the acts of Congress of May 8 and June 30, 1914. North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
RSC Insect Notes