Compared with most mites, this is a large species, roughly the size of your little finger nail (6-8 mm long). The adults are bright red with a velvety coating of fine hairs. They typically emerge from the ground after spring rains, in this case after a February rain in the Anza-Borrego Desert of southern California. They remain in the soil most of the year and only spend a few hours above ground, probably to feast on other prey which also emerge in great numbers after spring rains. The larvae are known to be parasitic on grasshoppers, while the adults feed on subterranean termites.

A Record-Breaking Mite At Walnut Grove Park In Twin Oaks Valley, City Of San Marcos, California Documented in Peer-Reviewed Scientific Journals

It is practically impossible to capture the quick multidirectional movements of these tiny mites in real-time with an ordinary smart phone or video camera. They appear like tiny dots and are easily missed if you blink. Try the following real-time mp4 video and see if you can spot the very quick erratic movements of several mites that appear like microscopic dots across the dirt clearing.   Short Real-Time mp4 Video Originally Taken At 1080P   Ideally you need a high speed video camera to capture the movement of these mites. In fact, I can barely focus on them with my unaided eye. In my case they are difficult to resolve because they resemble moving floaters in my vitreous humor, diffraction patterns cast on the retina by red blood cells 7.5 microns in diameter! I have captured many soil mites in my ant traps but none have the exceptional running and turning performance of Paratarsotomus macropalpis. In fact, this is precisely why scientists are interested in this remarkable creature, especially in the fields of robotics and biomimetics. Two cropped frames from the 10 frames taken in Burst Mode with 16x optical zoom (Sony DSC-HX9V). This large cat runs very fast in short bursts up to 60 mph. Once considered the fastest land animal, it was running in its enclosure in my direction while I stood on a hillside at the San Diego Zoo Safari Park. The specific epithet "macropalpis" of this unusual mite (Paratarsotomus macropalpis) refers to its palps that flank its tiny jaws (chelicerae).

When I first collected these mites I assumed they were house dust mites in the family Pyroglyphidae. My original assumption was based on their minute size and infestation in a house in southern California. The typical length of an adult body (excluding legs) is approximately 0.5 mm, slightly larger than an average grain of table salt (NaCl) that measures about 0.3 mm on a side. House dust mites are even smaller and are generally not visible without magnification. There are several reasons why I changed my original assumption, and have now concluded that they are parasitic mites of the family Macronyssidae and not house dust mites. Parasitic mites are very difficult to identify and require detailed microscopic examination. Based upon illustrations in Insects of the Los Angeles Basin by Charles H. Hogue (1993), they resemble bird mites of the genus Dermanyssus or rat mites of the genus Allodermanyssus. The fact that a rat was observed behind the wall in the same area where the mites were discovered is a strong argument in favor of rat mites.

Note Regarding Photography of House Dust Mites: These minute, translucent arthropods are only about 250 micrometers in length, smaller than an average grain of table salt. They are not visible without at least 10x magnification; ideally with 100x. They have 4 pairs of hairy legs, no eyes, no antennae, and a mouth region at the anterior end that resembles the head. Long setae (bristlelike hairs) extend from the outer margins of the body. Because of the lack of depth of field, all of these structures are difficult to capture with a camera attached to an ordinary light microscope. In addition, when preparing them on a microscope slide, the legs and setae are seldom all extended and visible. Ideally you need a scanning electron microscope or a good scientific illustrator. The following images of dust mites were taken with a compound microscope and a Sony W-300 digital camera (magnification 400x). Because of the limited depth of field, the bristlelike setae are not visible in most of the images. Left drawing modified from the Ohio State University Extension Fact Sheet on House Dust Mites: (http://ohioline.osu.edu/hyg-fact/2000/2157.html)

House dust mites are among the smallest arthropods. Because of their minute size and pale color, they are generally invisible to the naked eye. Although they vary in size, the typical length of an adult body (excluding legs) is approximately 0.25 mm, smaller than an average grain of table salt (NaCl) that measures about 0.3 mm on a side. In fact, the specimen I photographed is only about twice the length of a pine pollen grain! Dust mites of the genus Dermatophagoides are a serious household pest in southern California. Although they do not bite humans, they are a common cause of bronchial asthma and other allergies. Their chitinous exoskeltons and feces containing digestive enzymes are readily inhaled in airborne dust and serve as potent allergens that induce antibody and cell-mediated immune responses in hypersensitive people. Typical symptoms include itchiness, inflamed eczema, watering & reddening eyes, conjunctivitis, sneezing repeatedly, runny nose and clogging of the lungs.

A typical mattress may contain tens of thousands of house dust mites, not to mention pillows where you place your face. Dust mites prefer warm, moist areas where you are sleeping, although they are also common in carpets and sofas. Dust mites feed primarily on flakes of dead skin shed from your body each day. In fact, your bathtub ring is composed of dead skin cells in addition to grime and dirt. It is debatable whether dust mites and their fecal pellets add significantly to the weight of your favorite old pillow. Basic knowledge of dust mites gives new meaning to sleeping in motel beds. It might be reassuring to carry your own pillow, unless it is already mite infested. Dust mite exoskeletons and fecal pellets are the primary allergens involved in severe allergic reactions, so in a motel bed it probably doesn't matter whose skin cells the dust mites were feeding on. However, there are other concerns for hypochondriacs, including pathogenic organisms (viruses & bacteria), lice and bedbugs.

The following image shows how incredibly small these mites really are. They are compared in size with the reverse side of a U.S. Lincoln penny (one cent) and an ordinary grain of table salt (NaCl):

Of all the many thousands of plant and animal images I have taken and uploaded to Wayne's Word, this is truly one of the most amazing. It even surpasses the dust mites I found in my pillow. I didn't have to travel that far or spend a lot of money on gasoline or airline tickets. I didn't even have to look any further than my nose to find such a remarkable animal. In fact, I actually found this microscopic relative of spiders deep in a sebaceous gland of my nose. Most of the images were taken with a compound microscope and a Sony W-300 digital camera. Although the backlit, high magnification images appear two-dimensional with limited depth of field, you can clearly see the slender, fusiform body and eight stubby legs, each tipped with a pair of pincerlike claws. Illustration (left) modified from T. Ross and photos of the dorsal side of Demodex brevis by W.P. Armstrong.

Hair follicle mites of the genus Demodex are among the smallest multicellular animals. They were first described in humans in 1841 by Frederick Henle who reported this minute parasite from "miliary glands" of the ear canal. He was uncertain about the parasite's taxonomic position in the animal kingdom. [Henle is also known for the Henle's loop in the vertebrate nephron.] Another scientist from this time period by the name of Berger (1845) thought it was a member of the phylum Tardigrada. Tardigrades are minute animals often found on lichens and mosses. According to Desch and Nutting (1972), there are two species of follicle mites on humans. Demodex folliculorum measures 0.3 to 0.4 mm in length and typically occupies hair follicles. It is also called an "eyelash mite" because it commonly occurs in follicles at the base of eyelashes. Demodex brevis is about half that size (0.15 to 0.2 mm) and typically lives in sebaceous glands adjacent to hair follicles. The latter mite is only about the size of a unicellular Paramecium and appears to be the species I found in my nose.

These microscopic spider relatives (arachnids) live in the hair follicles and adjacent sebaceous glands of human eyelashes, noses, cheeks and foreheads. In heavily infested cases, the posterior ends of D. folliculorum can be seen around the bases of eyelashes. Their mouthparts resemble those of spiders, scorpions and other arachnids, but are much smaller. They are designed to feed on skin cells (cytoplasm) and the oily sebum produced by sebaceous glands. Males come out at night and move around on the skin surface to look for potential females to mate with. Unsubstantiated reports state that these mites can move on your skin at a rate of 8 to 16 mm per hour. Their digestive system is reportedly so efficient that they have very little excretory waste and no excretory orifice. This is reassuring news to those of us who worry about them defecating on our faces and in our eyes.

Most people have these minute parasites living relatively harmlessly in their skin pores and hair follicles, although people with oily skin, or those who use cosmetics heavily and don't wash thoroughly, reportedly have the heaviest infestations. They are transferred by facial contact and are apparently more common in adults than in children. In some people, high mite populations can cause demodicosis and blepharitis, possibly due to a suppressed immune system. Theses conditions are characterized by itching and inflammation of the skin and eyelids. High densities of Demodex have also been found in people with the skin disorder rosacea. A cell-mediated immune response involving cytotoxic "killer" T-cells may be involved in the inflammation associated with acne rosacea. There are numerous species of Demodex that live on many different mammals, including rodents, monkeys, cattle and bison. In fact, they have been found in 11 of the 18 orders of eutherian (placental) mammals, with most species harboring two or more species of Demodex (Desch, 2009). One species Demodex canis lives on domestic dogs and causes a condition called "demodectic mange." There is a plethora of information about these amazing animals on the Internet. You might start with an excellent summary of Demodex on Wikipedia.

All species of Demodex are obligate ectoparasites that cannot live independently of their host. In parasitism, the parasite benefits by obtaining nutrients from the host's body, which is often harmed by the relationship. In most humans, these ubiquitous parasites may not cause any harm to their host. In fact, some author's refer to the relationship as commensalism rather than parasitism. In commensalism, one organism benefits from the relationship while the other neither benefits nor is harmed. The dorsal fin of the remora is modified into a sucker which forms a temporary attachment to the shark. The shark does not seem to be inconvenienced by this and makes no attempt to remove the remora. When the shark feeds, the remora is in a good position to pick up scraps of food left by the shark. Marine mammals, including whales and manatees, often carry harmless hitchhikers called barnacles on their backs. The barnacles benefit from the ride through nutrient-rich waters. In my opinion, the term parasite is more appropriate because these mites are definitely feeding on human cells and glandular secretions (sebum). A few mites feeding on dead skin cells and sebum deep within hair follicles are probably harmless unless their populations get out of control. Recent peer-reviewed articles accessible through Google Scholar indicate there is considerable dermatological research on human follicle mites and different opinions regarding their detrimental effects.

.

The following images of a folicle mite came from my own nose. Based on its size and presence in sebum, it appears to be Demodex brevis. I squeezed a skin pore and collected the whitish sebum from sebaceous glands. With a toothpick I carefully transferred the sebum to a drop of olive oil on a clean microscope slide. [Other salad oils, such as soybean oil, will work just as well.] I added a cover slip and examined the slide under low magnification (40x) with a compound microscope using substage illumination (not a dissecting microscope). When I spotted a small fusiform body with eight stubbly legs, I switched to higher magnifications of 100x, 400x and 1000x. This may seem a little gross to some readers, but it is not nearly as shocking as the bot fly larva that emerged from a colleague's arm after returning from Central America.

Return To WAYNE'S WORD Home Page Return To NOTEWORTHY PLANTS Page Go To Biology GEE WHIZ TRIVIA Page Go To The LEMNACEAE ON-LINE Page