Arachnews: June 23, 2020

The latest news, art, and science from the world of arachnids.

Neville Park
Jun 23, 2020 · 9 min read

In this edition: synthetic silk, scorpion stings, social spider struggles, Spanish species surprises, and much more.

Terms in bold are defined in the Glossary at the end of the post.

Art & Social Media

Adorable tarantulas! Which species can you identify? • pikaole
“Gave me a lot of ’tude” • /u/WelcomeToMary
A pseudoscorpion in Nick Porch’s compost.
A Larinioides orbweaver nesting in a moth cocoon • Meghan Cassidy
Holoversia nigra harvester origami • Fernando Chura Huanca
The late Norman Platnick’s story, told by his son William on Humans of New York.
A jumping spider tries to steal a fly • Laura Hill via Tone Killick
A Common Yellowthroat pilfers from a spider’s web • Brad Balliett
It’s orbweaver spiderling time! • Phil Torres
Spiders as metal album covers, the thread • Nick Keiser

Education & Outreach

Watching animals from your home — and they can be anything from sparrows to spiders on windowsills — can give solace through the shift in perspective that the writer and philosopher Iris Murdoch called ‘‘unselfing.’’

  • The indispensable Helen Macdonald, reflecting on life in quarantine, discusses how simply observing animals can be an escape from our own circumstances. [NYT Magazine]
  • Alexandre Michelotto has an educational thread on pseudoscorpions, an under-studied and often-overlooked order of tiny arachnids. [Twitter]

Events & News

  • Three Bolivian boys goaded a black widow into biting them with the hopes of gaining superpowers. They were hospitalized for several days. They did not gain any superpowers. [Telemundo]
  • The American Arachnology Society’s virtual meeting is this week (June 25th–June 29th)! Registration for the meeting is now closed, but expect coverage of it here and on Twitter. [AAS]


Social orbweavers (Parawixia bistriata) in Argentina • Nicolas Olejnik
  • Parawixia bistriata, a South American orbweaver, is one of the rare species of social spiders. They live together in big colonies, hunting and feeding together. A fascinating paper finds that the type of prey affects whether spiders co-operate or fight over it. Younger, smaller spiders co-operate to take down prey. Moths are especially exciting, and so many spiders join in that no one spider can hog the catch. But when a spider can catch something by herself, her neighbour might try to fight her for it—and when that happens, the bigger spider usually wins. [Paper] [Sci‑Hub]
The fruit fly Anastrepha fraterculus Gerson Tavares
  • Some flies have markings on their wings that look (at least to us) like jumping spiders’ legs — the idea is that these might help the flies avoid being eaten by other jumping spiders. A study on the fly Anastrepha fraterculus, which has these markings, found that while this species is attacked less often that a regular housefly, removing the wing markings doesn’t affect this. Instead, the fly’s predator-response behaviour of presenting and moving their wings seems to be more important than the pattern on the wings themselves. [Paper 🔓️]
  • Just as habitats change as you climb a mountain, so do the species that live there. A new study of the spiders of Kozuf Mountain in North Macedonia discovers how different species live in different zones of the mountain. [Paper] [Sci‑Hub]
  • Here’s a new paper from the team who brought you that one on Arctic wolf spiders slowing climate change by eating each other rather than springtails. Warmer temperatures generally mean the spiders get bigger and have more offspring, but the researchers found fewer young than they expected. It seems increased cannibalism cancels out this effect. For more coverage, see the ScienceAlert article. [Paper] [Sci‑Hub]
  • Some animals travel by phoresy — hitching a ride on another species. Pseudoscorpions are particularly known for this behaviour. A new hitchhiker-transport relationship was just discovered: the pseudoscorpion Americhernes oblongus was found traveling on a fly from the genus Scipopus in Panama. This is also the first time A. oblongus was found in Panama! [Paper 🔓️]
The jumping spider Hasarius adansoni has bright white patches on its pedipalps • Nhobgood
  • Male Hasarius adansoni jumping spiders sport bright white patches on their pedipalps. These eye-catching markings help get female spiders’ attention—and possibly also predators’. One hypothesis is that males with more visible markings must be correspondingly better at avoiding predators, but recent experiments don’t bear this out. [Paper]

Pest Control

The quirky courtship of the thin-legged wolf spider Pardosa agrestisPardosaSpp
  • Neonicotinoids, or neonics for short, are a common type of insecticide, and have been in the news because they’ve been shown to mess up the chemical communication of a lot of insects. But what about spiders? The wolf spider Pardosa agrestis normally follows silk to a female and then commences a courtship dance. But in the presence of the neonic Mospilan, males were less likely to follow silk and to court. (Here’s a related paper previously featured.) [Paper 🔓️]
  • Pesticides often have a drawback — they can also kill natural predators of the pest in question. That is the case with the mite Blattisocius dentriticus, which preys on pests like cheese mites (Tyrophagus putrescentiae) and flat mites (Tenuipalpidae). The chemicals chlorfenapyr (a relatively new greenhouse pesticide) and chlorpyrifos (a widely used organophosphate) inhibit the growth and reproduction of this predatory mite. [Paper, in Chinese 🔓️]
  • What affects the number of citrus rust mites in an orange grove? A study tracked the population of this pest species and found that the mites vary in number, and where they are on the tree, based on the season, weather, and number of predatory mites in the area. [Paper 🔓️]
  • Does urbanization make European lizards more vulnerable to castor bean ticks (Ixodes ricinus)? A study from Poland found that sex, age, and habitat all interact to determine how tick-infested lizards are. Young lizards are less likely to have ticks than older ones. Males in natural environments have more ticks than in males in urban ones, but the effect is the opposite for females. [Paper 🔓️]

Health & Medicine

  • A recent paper gives a great overview of why controlling ticks and the diseases they carry is so challenging. For instance, the bacteria that cause many tick-borne diseases normally live in wildlife, which becomes yet another thing to control; people are unwilling to constantly do tick checks or pay a lot of money for pesticide application; a lot of products marketed as tick control don’t work; it takes ages to develop effective products and get them on the market; and pest management companies suck. The authors focus on the northeastern US, but similar factors operate elsewhere as well. [Paper 🔓️]
  • What happens when a pregnant woman is stung by a scorpion? A new study from Iran found that over 80% of the time, the baby is carried to term normally and without complications. But stings from some scorpion species, as well as stings to the head or torso, are more dangerous. [Paper 🔓️]
  • The neurotoxic venom of the North African scorpion Androctonus australis hector provokes a stronger immune response during the day, when stress- and immunity-related hormone levels are higher…IN MICE. Also, the authors abbreviate it as “Aah venom”, which is also what you yell when the scorpion stings you. [Paper] [Sci‑Hub]


  • Three new species of long-jawed orbweavers (Tetragnatha) described from South America and east Asia. However, the type material for three other Tetragnatha species is kind of sketchy, so those species might be removed eventually. So I guess it all evens out. [Paper] [Sci‑Hub]
What is the official name of this fossil amblypygid? • Poinar Jr. & Brown (2004)
  • Back in 2004, some scientists discovered a fossil amblypygid preserved in amber and named it Phrynus mexicana. In Latin, -us is a masculine ending and -a is feminine, so it really should be Phrynus mexicanus. The problem: a non-extinct species, Paraphrynus mexicanus, used to go by that name. Species names are like roller derby: they have to be unique, and names can’t be re-used…even if no one’s using them at the moment. A few years ago the discoverers appealed to the ICZN for an exception. Their case has been denied, and the fossil Phrynus mexicanus needs a new name. Watch this space for more gripping developments. [Paper]
  • While surveying spiders in Spain’s national parks, the researchers found something rather odd going on with a group of Theridion cobweb spider species. The results of DNA barcoding did not match up with species identification based on physical characteristics—nor molecular analysis based on a different gene sequence. How is this possible? The gene sequence used in DNA barcoding is from mitochondrial DNA, which is solely inherited through the maternal line. The second sequence they used is from genetic material in the cell’s nucleus, which is 50% the mother’s and 50% the father’s. There are a few possible ways this can happen. One is from interbreeding between different species. Another involves bacterial endosymbionts that are passed down via the female line, much like mitochondria. They have an ingenious way of skewing fertility so females without the endosymbionts can’t produce viable offspring. (See my earlier explanation; Ctrl+F “cytoplasmic incompatibility”.) Anyway, thanks to these interesting discoveries we have yet another Theridion species, T. promiscuum—a reference to the hybridization hypothesis. [Paper 🔓️]
  • Based on physical characteristics and genetic data, Euseius mites collected from plants in Brazzaville, Congo don’t seem to belong to either of the species common in the region. They may be new species, but it will require more analysis to sort out. [Paper] [Sci‑Hub]
  • A new cave-dwelling scorpion species, Euscorpius biokovensis, has been found in Croatia. It’s named after the Biokovo Mountains where it was found. [Paper 🔓️]
A Eurasian blue tit (Cyanistes caerulus) and its presumably mite-filled nest • Oldiefan
  • A survey of mites living in the nests of Eurasian blue tits (Cyanistes caerulus) reveals the population is largely made up of Dermanyssus gallinae, a common bird mite—relatively homogeneous as far as birds’ nests go. [Paper 🔓️]
  • The tick Haemaphysalis concinna, recently sighted in Poland for the first time, has been found on a deer in Lithuania. [Paper] [Sci‑Hub]
  • A survey of phytoseioid mites in Iranian greenhouses turns up 21 species, one of them (Podocinum sagax) a first-time find in the country. Many of these mites prey on plant pests, and some are raised commercially specifically for pest control. [Paper 🔓️]
  • Three new species of Lurchibates water mites found parasitizing newts in southern China. The mites seem to only parasitize certain newt species, which offers tantalizing clues about how to find more. [Paper] [Sci‑Hub]

As always, thank you for reading! Even more thanks than usual to Sebastian Alejandro Echeverri for doing the heavy lifting for this edition. Suggestions, corrections, and other feedback are welcome; just drop us a (silk) line at @arachnofiles. 🕸


  • Amblypygi: a group of arachnids known as tailless whipscorpions, whip spiders, or just amblypygids. Adapted for life in caves and crevices, they are thin and flat, have long, clawlike pedipalps, and have turned their front pair of legs into thin whiplike antennae which they use to feel around in the dark. They don’t make venom or silk and are harmless to humans. Some of them You can put them on your face!
  • endosymbiont: A symbiotic organism (-symbiont) that lives inside (endo-) another species. Typically these are bacteria living inside the cells of plants or animals. We covered a lot of arachnid endosymbionts in the March 9th issue of Arachnews.
  • DNA barcoding: a method of identifying an organism by comparing one of its genes to the same gene from different species. In animals, the standard gene is usually mtCOI, which comes from mitochondrial DNA. But there are other “reference” sequences from different kinds of genetic material, like ribosomal RNA.
  • ICZN: International Commission on Zoological Nomenclature. This organization writes and enforces the many, many rules on how to name animal species.
  • mitochondria: the powerhouse of the cell. Once free-living bacterial freelancers, mitochondria moved inside other cells and then kind of never left. They still retain their own small genome. When two sex cells fuse, the new organism’s mitochondria come from the egg, and mitochondrial DNA is therefore always passed down through the female line.
  • phoresy: travelling by hitching a ride on another animal. Many mites and pseudoscorpions are phoretic.
  • type material: the official specimens used to define a species. Type specimens are preserved in museum collections for reference. If the specimens are in bad condition or don’t match the species description, the species might get reclassified or even removed.


Arachnids are fascinating.

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