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Bed Bugs, House Dust Mites - What's the Difference?
Sometimes people can mix up these indoor pests, so this blog post will describe some of the differences between the two.
The main noticeable difference is size. Bed bugs are visible to the naked eye. Adult bed bugs are about 5 - 7 mm in size. So they are comparable to the size of an apple seed or about half the area of your pinky fingernail. In contrast, dust mites can really only be seen under the microscope. House dust mites are about 0.1 - 0.4 mm long, less than one tenth the size of a bed bug, at least. House dust mites are translucent to white in colour and have been described as "globular" in shape. Although young bed bugs (called nymphs) are translucent to yellow before they have fed, once they have a blood meal they are red. Adult bed bugs are brownish and have flat, oval shaped bodies before feeding and are more reddish, elongated and round after feeding. Other differences in appearance come down to the different categories that these organisms belong to. Bed bugs are members of the insect class, which means (among other things) that they have a pair of antennae and three pairs of legs. Dust mites on the other hand aren't insects at all! They belong to the arachnid class, so they have eight legs, no antennae and are related to spiders.
What about feeding and lifestyle? Well, bed bugs are parasites. This means that they benefit at the expense of their hosts, and unfortunately their hosts can be humans. Specifically, bed bugs pierce the skin and feed on the blood of vertebrate animals including humans. Unlike some other blood feeding parasites, bed bugs don't remain on their host. Once they have finished their meal, which takes about 5 minutes, they move away from their "victim" and hide in a nearby nook or crevice. This is the reason why although it is physically possible to see bed bugs with the unaided eye, you often won't catch site of them on your bed or other furniture. House dust mites are not parasitic and they cannot bite you. Dust mites feed on "dander," which is skin scales or flakes shed from people and animals and often found in dust. Lastly, adult bed bugs can live for 6 - 12 months, though this depends on feeding, while adult dust mites have an approximate life span of 1 - 2 months.
Despite all their differences both bed bugs and dust mites can cause problems for the people whose houses they share. For some people bed bug bites cause an itchy, red skin reaction while other people don't react at all. The greater harm can be psychological. Many people are understandably greatly distressed by bed bug infestations. House dust mites cause harm because of the allergens present in their bodies, fecal matter and secretions. Inhalation of these dust mite allergens can cause symptoms such as asthma attacks and wheezing.
In this blog post we have only scratched the surface of the bed bug and dust mite fields of knowledge. Our research team have studied them far more closely and are travelling to Orlando for the 2016 International Congress of Entomology (ICE 2016). Dr Natasha Gordon is giving a presentation on her bed bug research and Rose Waldron is presenting a poster on her house dust mite research. The poster that Rose is presenting at the ICE 2016 conference is about her experiments studying how dust mites react to dry conditions. House dust mites thrive at high (70 - 80%) relative humidities, but cannot survive well at relative humidities less than 50%. Natasha's conference talk is about her use of molecular techniques to discover a new way to detect bed bugs. In the last decade incidences of bed bug infestations have increased, so it is important to devise methods to detect the presence of these pests.
- Bedbugs in the 21st Century: The Reemergence of an Old Foe. Williams, K. and Willis M.S. Laboratory Medicine Aug 2012, 43 (5) 141-148.
- Mites and other indoor allergens - from exposure to sensitization and treatment. Raulf, M. Bergmann, K.C., Kull, S. et al. Allergi Journal International (2015) 24: 68.
- University of Florida - Featured Creatures. Common name: House Dust Mites, Scientific name: Dermatophagoides spp.
- House Dust Mites (ENTFACT-646) - Entomology at the University of Kentucky.
- Bed Bugs Biology. Centers for Disease Control and Prevention
Thanks to Maiklas Duda for his help in reviewing the literature for this blog post.