Archive for the ‘Mesostigmata’ Category

Mites in the News

February 4, 2015

Zerconid_Idaho_3As the Good Book says: “To every thing there is a season, and a time to every purpose under the heaven” (Ecclesiastes 3:1). The last year hasn’t been the season for much new at Macromite’s Blog. Mites, alas, have been getting short shrift and I’ve been chasing platypus and butterflies and littering Facebook with the result. However, while I’ve been trudging around my new neighbourhood under the skeptical gazes of the kookaburras and wallabies, others have taken up the mite-art palette and brush with outstanding success.

Sam Bolton (or ‘Bolten’ as The Guardian misspelled his name) struck first in classic greyscale with his ‘Buckeye Dragon Mite’. Such is the power of a good monster picture that I’m told his paper was the most downloaded from The Journal of Natural History last year. Let’s hope someone also cites the paper in a scientific journal or two.

And now, Martin Oeggerli’s long quest to bring the wonders of the acarine world to the public’s attention has been fulfilled. Quite a spectacular feat, both in colour use and in attracting the attention of National Geographic, something that several acarologists that I know of were not able to do. But if you compare Martin’s header image – a zerconid mite – with my more pedestrian zerconid image above, it is easy to understand his success. The text is by Rob Dunn (and The Inquisitive Anystid and I checked it for accuracy).

For those who are not squeamish (and if you are please don’t go there), y0u can see Rob among others bringing you up-to-date on follicle mite research in this video:

Even I am feeling itchy after watching that, but at least the rumour they explode on your face has been put to rest.


Moving to and fro on leaves: Phytoseiidae

July 20, 2012

Phytoseius oreillyi – Peter O’Reilly’s Leaf Rover

There are good mites, and bad mites, and many that are indifferent, but not many mites that are our friends. The Phytoseiidae (Acari: Mesostigmata), however, are our friends. This is because we share a common interest: spider mites (many of which are really bad mites). The species pictured above belongs to the type genus of the family: ‘Phyto’ (Greek for plant) and ‘seius’ (Greek for one who moves to and fro, or  shakes). The generic name perfectly captures the Gestalt of the family: they are mites that scurry across leaves looking for other mites to eat. This species was named for (Big) Peter O’Reilly of OReilly’s Guesthouse in Lamington National Park, Queensland. Although Peter preferred birds, he was always supportive of scientific research, even on mites. This species lives on the leaves of rainforest trees in the canopy of Lamington National Park. Peter seemed delighted that I named the mite for him, but Peter was never less than polite, so he may have been humouring me.

Man’s best mite friend: Phytoseiulus persimilis

O’Reilly’s Leaf-Roamer may or may not be of help to us in our long war with spider mites, but its cousin the Chilean Predatory Mites (Phytoseius persimilis) certainly is. The common name may or may not be accurate. The species was first described from the Mediterranean Region by the great Belgian-French acarologist Claire Athias-Henriot, but it was a cosmopolitan synathrope long before it was described. Our agricultural systems are very favourable to spider mite outbreaks. Phytoseiulus persimilis is a specialist predator  of spider mites, especially those that produce dense webs of silk such as the Two-spotted Spider Mite (Tetranychus urticae), a very bad mite. Although it tends to follow us around, good biological control requires using your predators at the appropriate time in the prey’s population cycle. Fortunately, nowadays you can buy boxes of Chilean Predatory Mites to sprinkle on your greenhouse crops, strawberries, and other crops to fend off damage by spider mites.

Amblyseius sp. – a genus with many good mites

A triple tribute to Funk: Funkotriplogynium iagobadius

July 7, 2012

Juvenile antennophorine mite

For no particular reason, other than it being a really good mite, I offer a view of a very dead juvenile collected in association with the infamous Funkotriplogynium iagobadius Seeman & Walter, 1997. Mites in the Antennophorina (Mesostigmata) are best known as associates of large arthropods, especially beetles and millipedes, but some live with ants, bees and termites, and others with cockroaches and earwigs living in stable habitats such as under rocks and in logs. For example, Paradiplogynium nahmani Seeman, 2007, was described from Australia’s Colossus Earwig Titanolabis colossea (Dohrn 1864) – at about 6 cm long, one of the World’s largest Dermaptera. Antennophorine mites are no slouches when it comes to size either. Adult Diplogyniidae, the earwig mite’s family, usually approach a millimetre in length and some of the Megisthanus on passalid beetles reach 5-6 mm in body length, as large as some ticks. Diplogynium Canestrini, 1888, type genus of Diplogyniidae Trägårdh, 1941, is but one of forty-odd genera and almost 100 described species in that family , and although the largest family of Antennophorina, is but one among 21 families grouped in 7 superfamilies.

Mop-like cheliceral excrescences of Micromegistus – an associate of carabid beetles

In spite of these mites being relatively large and living on often well-studied arthropods, little is know of their life history. The ant associates in Antennophorus make their living by making ants regurgitate food (sounds disgusting, but it’s a life). But for others it isn’t clear: the adults hang out on their hosts doing something with their mouthparts from which large mop-like excrescences dangle. What they are doing, however, is a mystery. Some authors have hypothesized that they feed on the ‘dermal secretions’ of their hosts. The larvae and nymphs are usually not found on the arthropods, so they are almost completely unknown, but some have been found wandering in galleries and have been thought to ‘scavenge’ or feed on fungi, the usual default guesses for  ‘I don’t know’.

Mysterious mouthparts of Megisthanus – an associate of passalid beetles

Fortunately, not all Antennophorina are inveterately found on large arthropods: a few are more or less free-living. One such group is the rather plesiotypic family Triplogyniidae, based on the then new genus and species Triplogynium krantzi Funk, 1977, from Central Africa. In 1985 AK Datta described a second genus in the family and added Dick Funk’s name to create the rather earthy, but not at all syncopated, name Funkotriplogynium. This latter genus also occurs in Australia and a student, Owen Seeman, and I were able to both observe feeding by the adults and describe the juveniles. This gave us an indication that predation was the basal mode of feeding in Antennophorina and gave Owen the opportunity to win fame and infamy with his species name. Owen has a lot of things to answer for (my having to feed chickens the first thing in the morning immediately comes to mind), but he has earned his spurs as an acarologist by almost singlehandedly exposing the mysteries of antennophorine development and ecology. Although much remains to be explained, including the function of those fabulous excrescences, it seems clear now that taking a bite out of whatever arthropods or worms are encountered while wandering in the galleries and nests of their hosts is the first thing on the minds of many antennophorines.

These teeth were made for biting and that’s just what they do


Datta AK. 1985. A new genus and species of the family Triplogyniidae (Acari: Mesostigmata) from Assam, India. Indian Journal of Acarology 9: 48-56.

Funk RC. 1977. Triplogynium krantzi n.g., n. sp., type of Triplogyniidae (Mesosligmata: Celaenopsoidea). International Journal of Acarology 3: 71-79.

Seeman OD & Walter DE. 1997. A new species of Triplogyniidae (Mesostigmata: Celaenopsoidea) from Australian rainforests. International Journal of Acarology 23: 49-59.

Seeman OD. 2000. The immature stages of the Fedrizziidae (Mesostigmata: Fedrizzoidea). Acarologia 41: 39-52.

Seeman OD. 2007. A new species of Paradiplogynium (Acari: Diplogyniidae) from Titanolabis colossea (Dohrn) (Dermaptera: Anisolabididae), Australia’s largest earwig. Zootaxa 1386: 31-38.

Seeman O.D. 2012  Larva and deutonymph of Promegistus armstrongi Womersley (Acari: Mesostigmata: Trigynaspida: Promegistidae). Memoirs of the Queensland Museum – Nature 56(1): 255-269.

Conundrum of the Cusps: Or too many teeth

December 17, 2011

Snap and Grab: One way to snare a springtail

One of the interesting things about the human mind is that although we tend to be fascinated by the diversity in Nature, we endlessly try to simplify what we see, to control Nature by reducing it into a smaller number of units. We value simple explanations over complex ones and even codify this preference in science with Occam’s Razor. This has various formulations, but Frustra fit per plura quod potest fieri per pauciora at least comes from Occam’s writings and fits this posting: ‘It is futile to do with more things that which can be done with fewer’.

Another long bite for a springtail

It is winter now, if a rather mild one so far, but still not the best time for observing living arthropods. However, a friend has posed a challenge – how many living arthropods can you find during winter in Alberta? So, I’ve been wandering around the house taking bad pictures of tiny insects and far too large spiders and trying to coerce my wife into taking better ones. However, exams and marking reign at the moment and she suggested: why not see what is living in the soil of our house plants? Brilliant idea! – at least 21 species in the first extraction, 2/3rds mites, but also 7 species of Collembola – springtails. As I was perusing said springtails I noticed that the large entomobryid and isotomids all were missing the distal segements of their antennae.

Entomobryid springtail with its antennae intact

Although Tennyson’s “Tho’ Nature, red in tooth and claw, With ravine, shriek’d against his creed [i.e  God’s]” is most colourfully exemplified by vertebrate predators at their dinner, you can get an idea of what life in the soil is like for springtails by viewing Jeffrey Newton’s entertaining video. The spring in the springtail is one way these animals avoid being eaten, as are the slippery scales on some (as in the SEM above) and the chemical defenses of others. Apparently, shedding the ends of the antennae is another (good news is that they can grow back – as one victim with half-regrown antennae demonstrated).

Another snap & grab - but more shear-like than toothy

In my house plant ecosystem, the antenna-snapper seems to be a species of Holaspulus. These are rather large predatory mites (Mesostigmata, Parholaspididae) more typically found in tropical areas. But then, I guess the greenhouses these plants came from do all they can to mimic the tropics including, it seems, hosting tropical mites.

Long snapping chelicerae on a Holaspulus adult female

As you can see from the image above (this mite is from Queensland), Holaspulus  have very long chelicerae, almost half the length of their body. These chalicerae can be shot out to snap and grab prey, such as springtails. I know this is true through my own observations, but I also know this for the other chelicerae of the very different mites illustrated above and several other unrelated genera.  Just as springtails have a diversity of means of escaping becoming dinner, so do their predators of capturing them.

Diagram of Holaspulus chelicera deployed: snap and grab

And just to keep things clear as mud, I know of many mites with much less impressive chelicerae that also seem to have no problem catching springtails, e.g. the parasitid mites in Jeffrey’s video. Another example,  species of Podocinum have fairly typical chelicerae, not obviously enlarged at all, but are seemingly efficient predators of springtails.

Business end of a Podocinum: not at all springtail-challenged

Such cheliceral modesty is true of many mesostigmatans that prey on springtails – they lack the snap-trap type of chelicera. But  some such as Podocinum species do have extraordinarily attenuated legs.

Podocinum fishes for springtails with it elongate front legs

I’ve watched Podocinum fishing for springtails. They are slow-moving, stately mites, but as they wander the front legs dangle in front exploring their world. When a springtail is encountered by the light touch of the long distal setae, the mite pauses, and then quickly scopes their prey in towards their chelicerae: another springtail become mite fodder.

Epicriid mite with sticky setae to trap springtails

Epicriid mites carry this long-legged fishing one step further. The long ventral setae on the tips of the front legs have blobs of glue with which they capture their collembolan prey (see Alberti 2010*). So we have yet another way to scarf-up a springtail, but why such diversity in such a simple pursuit?

Another toothful springtail nemisis?

As far as I know, no one has studied the feeding behaviour of the mite above, but I suspect springtails are part of its diet. For those who like a challenge, try naming the unnamed cheliceral images. A genus would do and you have five such unlabelled images to guess upon.

I know of only one genus with multiple rows of retrorse teeth - care to guess?

*Alberti, Gerd. 2010. On predation in Epicriidae (Gamasida, Anactinotrichida) and fine-structural details of their forelegs.  Soil Organisms  Volume: 82  ( 2);  179-192.  (Open Access – search for the title and the pdf is yours)

Acroseius, Polyaspinus, Trachytes: Cerotegument Galore

June 5, 2011

Acroseius - undescribed species from Queensland - venter

I recently had a request for an image of Polyaspinus tuberculatus Womersley, 1961 and I realised that my Polyaspididae, I mean Trachytidae (current usage), were not in very good nick. Actually, the mite in question is now Acroseius tuberculatus (Womersley, 1961) too.

Polyaspinus sp. (probably undescribed) from Queensland - venter

The short answer is that I do have images of what appears to be an undescribed species of Acroseius and also a probably undescribed species of Polyaspinus from Queensland. I also have an undescribed Polyaspinus from Alberta (no image yet) and a species of Trachytes  that is probably described from Oregon.

Trachytes sp. from Oregon - dorsum

All of these mites are interesting for several reasons, but I will have to wait to post on that – I’m being dragged off on family duties.

New Photo-Electron Challenge & Old Answers

May 14, 2011

What is my secret name and what do I want from life?

‘To-morrow, and to-morrow, and to-morrow, Creeps in this petty pace from day to day’, but at last the the tomorrow promised in the last post (in March no less) has finally arrived. I plead overwork – I’ve had two massive taxonomic projects to complete including a listing of all of the species of mites known from Alberta – before the new field season commences.  Above is one of these little monsters saying high and below are a number of them clinging to an insect collected from a rotting oyster mushroom (Pleurotus ostreatus). Any guesses to the mite, insect, spores, ecological interactions?

Mites & insect - name them both and what is happening.


I’m fairly pleased in how well everyone did in the first Photon Challenge, especially considering the quality of the pictures.  Ray even got the fly to genus and Kaitlin got pretty close to the family of the mesostigmatan – at least according to the Manual of Acarology 3rd Edition the Halolaelapidae belongs in the Rhodacaroidea and they certainly are phoretic as deutonymphs, as one would expect in that superfamily. So Kaitlin gets points for that. Bruce got the family, and, I believe, the genus correct, at least in the broad sense: Halolaelaps s.l.  Bruce has the advantage of having described the only known Australia species of the group and to have pointed out how messy the generic concepts are (see Halliday 2008 Systematic & Applied Acarology 13, 214–230). I am neutral on what superfamily Halolaelapidae belongs to – Rhodacaroidea is unlikely to be monophyletic and deutonymphal phoresy is probably a ‘primitive’ behaviour in Mesostigmata.

Deutonymph of Myianoetus - note bifurcate claws

Alas, no one guessed the genus of the histiostomatid – Myianoetus! All acarologists should know this genus if only because it contains one of the few mites to lurk among the pages (as an anoetid) of  a large circulation, general science magazine – Science itself – and the interesting concept of ‘fly factors’:

Greenberg & Carpenter (1960) Factors in Phoretic Association of a Mite and Fly. Science 132: 738-739.

“Abstract: Combined rearing of the mite Myianoetus muscarum (L.), and the fly Muscina stabulans (Fall.) has revealed adaptations of the hypopus to a series of fly factors. These adaptations favor the mite’s dispersal. Hypopi are attracted to the pupa by a volatile substance and cluster on the anterior end, from which the fly emerges.”

Read the whole thing, as they say, but, although published over 50 years ago, you will still need access to Science to do so (and to read the next paper entitled  ‘Licking Rates of Albino Rats’). Rat licking trailer aside, I think the most interesting thing about the Myianoetus paper is that I can’t remember any follow-ups that explain ‘fly factor’ or ‘beetle factor’ or ‘ant factor’. Most of the chemical clues used to induce or terminate phoretic behaviour in mites remain unknown. Only skatoles and dung beetles come to mind. If someone out there in the ether knows of other studies, please let me know – I can use the information to help a student.

Photon Challenge: Last Chance

March 19, 2011

Business end of Antennolaelaps

Well, this Photon Challenge has gone on long enough: last chance for demonstrating your acarological expertise. Tomorrow I will reveal all.

Kaitlin and Ray have done well to the family level of the histiostomatid, but I don’t think a leap to the genus is impossible. After all, just how many mite genera have made it into the pages of Science magazine?

Ray has an embarrassingly detailed grasp of the anthomyiids breeding in indelicate accumulations of organic matter. But no one seems to be willing to stick their neck out on the phoretic mesostigmatan deutonymphs with two dorsal shields that have a death grip at the base of the abdomen of the Eutrichota. Last hint: the family of the phoretic mesostigmatan is currently placed in the same superfamily as the Antennolaelaps featured above.

Photon Challenge: New Hints

March 5, 2011

A closer view of a mitey fly

Kaitlin and Ray have both demonstrated that even the smaller of the two mites hitching a ride on our fly can be identified to family from a not so great photo: heteromorphic deutonymphs (aka hypopi) of a member of the Histiostomatidae. They also correctly placed the larger mite to order: Mesostigmata. Not much luck on the fly, though, so I guess that means mites are easier to identify than flies? Anyone who has struggled with the generic key for this family in Nearctic Diptera might very well say yes. However, the family of the fly should be an easy guess for a dipterist.

Genus anyone?

Here’s a light microscope view (this is a Photon Challenge) of the venter of one of the histiostomatid hypopodes (yet another name for these deutonymphs) and a closeup of one of the pretarsal claws. The ventral shot is layered from three images in the wonderful CombineZP and the claw from two shots. The host association and characters visible in this image should give the discerning astigmatologist a good guess at the genus (I have checked with the North American authority on this one and he had no problem).

I’ll give one more hint on the mesostigmatans too – they also are deutonymphs.

Biennial Bits & Pieces: Bat Mites

November 28, 2010

A patch of soft tick cuticle

The data is in and my hypothesis that putting up bits and pieces of mites would increase my frequency of posting is falsified (sorry Kaitlin). In fact, in spite of the interesting discussion the last posting generated, and my intent to propose a General Theory of Oribatid Mite Leg Well Ornamentation (sorry Dave, could not resist the pun), I have let other duties drag me away from macromite. Now all is snow and ice and bare trees, though, and so sitting at the computer on a Sunday morning no longer seems like chore. So how about a bit of a bat mite – or tick if you prefer?

Ventral view of a soft tick nymph Carios sp.

As a general rule, mammals are an okay habitat for mites: primates, even lemurs, carnivores, even and odd toed ungulates, sloths, armadillos, shrews, hares, rabbits, rodents, and marsupials all sport specialized mite parasites. Even duck-billed platypuses and echidnas have to deal with ticks and chiggers. Whales, dolphins, and porpoises are an exception – as far as I know they seem to have left their mites behind when they moved into the ocean – but other marine mammals such as sea lions, elephant seals, fur seals, and walruses are hosts of nasal mites in the family Halarachnidae. It is the bats, however, that seem intent on outdoing all other mammals in terms of the diversity and creepiness of their acarine inhabitants with at least 18 families and over 1000 species known. Several of these families are restricted to bats and there is even a genus of soft ticks, Antricola, that are exclusively parasitic on bats (well, there was a genus, recent research submerges Antricola into Carios).

Say hi to a bat mite and be glad you are a primate

Of course, bats are ONE OF the most successful group of mammals, with about 1,100 species known (~20% of all mammals), so this is only about one species of mite per species of bat. In comparison, only about 3,000 species of bird mites are known (from ~10,000 species of birds). So, either a higher proportion of bat mite species have been found or bats are great hosts. A simple explanation for the success of mites on bats is that bats like to hang out close together in protected spots and tend to be philopatric – they like to return to the same spot. Presumably these behaviours help bats to survive, but they also make life easy for parasites: lots of bats to eat and if they get bored with one bat, it is relatively simple to move to another. One of my favourite families of bat mites is the Spinturnicidae. These mites spend their lives on the wing membranes of bats and suck their blood and, well, they are strange and rather creepy looking – all fat legs and long hairs, especially in males where the body behind the legs is highly reduced (somewhat as in sea spiders).

Venter of male spinturnicid bat mite: X-leg arrangement is a good character

Spinturnicids have been the subject of a fair amount of scientific study and some of the most interesting has been published by a Swiss researcher at the University of Lausanne, Nadia Bruyndonckx, and her colleagues (from around the world). One of their recent papers (see below) tested for co-speciation between European bats and spinturnicid mites. They found some evidence for co-speciation, but also for failure to speciate and for host switching. So, like much of evolutionary history, that of bat mites is complicated. That may be especially true in North America. Those behaviours that have favoured mites in the past probably facilitate the spread of whatever agent causes white nose syndrome: bat mites here may be facing a lonely future.

For more on bat mites see:

Bruyndonckx, N., Dubey, S., Ruedi, M., Christe, P. (2009): Molecular cophylogenetic relationships between European bats and their ectoparasitic mites (Acari, Spinturnicidae) Molecular Phylogenetics and Evolution 51: 227–237

Krantz, G.W. & Walter, D.E. (eds.). (2009): A Manual of Acarology 3rd Edition. Texas Tech University Press, Lubbock, 807 pages

Walter, D.E. & Proctor, H.C. (1999): Mites: Ecology, Evolution and Behaviour. University of NSW Press, Sydney and CABI, Wallingford. 322 pp.

Mouthparts and genital opening of male

Mite Farm or Some animals are more equal than others

February 14, 2010

Microscydmus – a very small beetle that eats even smaller mites

Although possibly apocryphal, one John BS Haldane is claimed to have mused that the Creator had an inordinate fondness for beetles. With all due respect, though, I note that one might also make this claim for mites. Because of their small size and insinuatory nature, mites readily associate with many different kinds of organisms both externally and internally. These various symbiotic (=living together) relationships may be good for the mites and bad for the host (parasitism); good for the mites and good for the hosts (mutualism); good for the mites and of little importance to the host (commensalism); or mysterious (i.e. unstudied and unknown, but still living together). Now there are some insects that actively seek out mites with dinner in mind. The Microscydmus beetle above, about 0.63 mm in length, was a bit of a bully and attacked only mites half its size (Mollerman & Walter 2001 Acarology: Proceedings of the 10th International Congress). But in general, it is the mites that do the seeking, and beetles are often the habitat of choice.

Some mites are larger than the smallest beetles, but the smallest mites are in a class by themselves

Australian carabid beetle hosting Micromegistus mites

Although mites like to hang out on beetles, not all beetles are equally attractive. Beetles that live in discrete habitats seem to have the most mites. Ground beetles (Carabidae) that like to hide under logs or rocks, for example, are a prime mite habitat. Many beetles have a peculiar fascination for dung and most of these have similarly prurient mites hanging on to them, at least to and fro the dung pat. Hitching a ride on a winged animal (phoresy – ‘to be carried’) is the norm in mites that live in patchy habitats such as flowers, tree holes, beach wrack, compost piles, carrion, and dung. Some dung mites like to hang onto dung flies, but by far the majority prefer to use beetles. Indeed, the fascination that mites have for beetles does seem to go well beyond the ordinary and well beyond the dung pat. Take almost any beetle that lives in wood and you may find them covered with mites. For example, the Mountain Pine Beetle (MPB Dendroctonus ponderosae) that is slaying its way through Canada’s lodgepole pines has at least a dozen different kinds of mites that hitch a ride from dead to dying tree on the beetles in Alberta. The better known and just as pine-unfriendly Southern Pine Beetle (SPB D. frontalis) has more than 100 species of mites associated with it over its broad range. These mites do just about anything one could imagine, from feeding on the beetle larvae, to feeding on potential beetle antagonists in the galleries, to feeding on fungi, to transmitting their own preferred fungi that may out compete the fungus the beetle grubs need to survive (and thus bring an outbreak to a halt).

Promegistus armstrongi – one of many kinds of mites found on ground beetles

One could go on and on about mites’ fondness for beetles, and I’m just the kind of person who might want to. However, it is Valentine’s Day and I’m making dinner for my wife, so I’ll end on an exceptional note. Even among the beetles, some beetles are more mitey than others. I think the pre-eminent position must be held by the beetles of the family Passalidae – Betsy Beetles. More than two dozen different families of mites make their homes, or at least their transportation, on Betsy Beetles. Many of these are only known from these beetles – although little is known about the interactions. In many cases, as with the extremely large (up to 5 mm in length) mites in the genus Megisthanus, only adults are found on the beetles. Although these mites have fearsome-looking chelicerae, they seem to do the beetles no harm and when living off the beetles in their galleries in logs, feed on other small invertebrates and possibly help keep beetle pests down. What seems most likely is that the adult male mites use the beetles as a place to find mates (usually only one male is found on a beetle, although several females are often present) and the mated females disperse to new logs on the beetles.

Very large Megisthanus mites on Betsy Beetle

Feasome looking chelicerae of Megisthanus

Saltiseius hunteri - a passalid mite that jumps

Saltiseius hunteri – a mite that jumps onto betsy beetles for a ride

As I warned you, I could go on and on and on about beetle mites, but I think I’ll end here for the moment with one of the better known associations – sextant sexton beetles (Nicrophorus spp.) and Poecilochirus mites (Parasitidae).  The exceptional research by David Sloan Wilson and others has demonstrated that this classic mutualism between mites and beetles is actually a bit more complicated – it can vary from mutually beneficial to parasitism depending on circustances. And that is probably true of most of these associations. Although we like nice clear answers, simple dichotomies, real life is just one complication after another.

An outraged Nicrophorus beetle feeling the pinch, but probably liking the mites