On October 18th, 2017 we learned about

Tactile stealth makes mosquitoes more successful at sucking your blood

In addition to keeping your guts in, germs out and providing a convenient canvas for tattoos and scars, your skin is your body’s largest sensory organ. It’s loaded with different types of nerve cells to pick up tiny changes in pressure that might spell trouble for your body, from a cactus needle to a parasitic insect. Unfortunately for us, insects like mosquitoes have evolved adaptions to our epidermal warning system, giving them a chance to sneak in a bloody snack without drawing our attention.

Sneaky stabbing and sucking

When a mosquito “bites” you, it’s actually piercing your skin with its proboscis. In insects like butterflies, the proboscis is a long, delicate tube that is used to suck up nectar from a flower. In a mosquito, it’s a bit more weaponized, and is actually a sheathed set of six thin needles called stylets. Two stylets have tiny teeth to cut through the skin, but they’re sharp enough that they can slip between your skin’s sensory defenses. The next two stylets push the incision open, followed by a labrum that senses for blood vessels.

Finally, the hypopharynx covers the top of the labrum to make it into more of a tube, as well as drip drool back into your incision. In addition to passing pathogens to our bodies, the drool keeps the blood from coagulating, or clotting, too quickly. This allows the mosquito to get her fill of blood cells, even taking the time to poop out excess water while she sucks.

Soft, delicate departures

A mosquitoes departure is no less specialized, as all that blood would go to waste if we detected the parasite and squashed before it could escape to lay eggs. Many insects, and birds and probably pterosaurs, kick-start their flight by pushing off the ground, or skin, with their legs. By catapulting themselves into the air, they save their wings some work and get moving faster. The catch is that they’re exerting all the force of their liftoff in one quick movement, which means that that force feels more punctuated and noticeable to your skin.

To make their departure as gentle and subtle as possible, mosquitoes shift the work to their wings. 61 percent of a mosquitoes liftoff is powered by its wings, which get to push against the air instead of your skin. Their longer legs than the average fly allow them to push with the same amount of force, but that force can be spread out over a longer amount of time. All these adjustments soften the impact of mosquito take-offs, but without sacrificing speed compared to other flies. The one catch is that a belly full of blood does weigh them down a bit, as they move around 18 percent slower in the air than unladen insects. This means a mosquito’s final escape is just less than one mile an hour, although we’re usually too distracted by the histamine-induced itching to notice.

Source: The physics of mosquito takeoffs shows why you don’t feel a thing by Mariah Quintanilla, Science News

On October 11th, 2017 we learned about

Three repulsive reasons to keep houseflies from coming in contact with your food

So you probably weren’t about to invite a fly to land on your food, or even your body, but were you sure about why you had that instinct? Sure, it’s a good rule to not want any creature to sit in the food you’re about to eat, but houseflies quite literally bring a few extra-gross features to the table. Amazingly, the most concerning of a housefly’s activity isn’t their vomit or possibly even their feces, because the nastiest stuff tends to be stuck to their feet.

Puking on your food

Houseflies (Musca domestica), like other insects, can’t chew like you can. Like tiny, more irritating babies, they need their food to be soft and mushy, but without teeth or even jaws they have to liquefy things chemically instead of mechanically. To soften up a blob of food, they barf up a droplet of “regurgitate,” which is basically digestive enzymes that less revolting creatures would keep inside their bodies, or at least some kind of stabby mouth part. Housefly mouths are only good for lapping and sponging up liquids, so they either leave a bit of enzyme hanging off their tongue to help get at softer food, or spew a bigger dose on food that needs more time to break down.

Pooping on your food

Once the food is soft enough, the fly can then lap it up where it will be further digested in the insect’s midgut. Fly digestion, like yours, produces waste, and flies are likely to poop once they’ve gotten stripped their liquefied meals of their nutritional value. This does not mean, however, that they poop every time they land. They poop frequently enough to create what can look like splatter patterns if you know what to look for, but they’re not defecating every time they touch down on you or your food.

Pathogens on your food

As icky as vomit and feces may be, they’re not the most concerning part of a fly landing on your food. Fly feet and bodies are actually much more likely to carry and spread pathogens like, including bacteria that can cause cholera, dysentery and typhoid. A brief touchdown probably isn’t a huge reason to worry, as not enough bacteria will be transferred to necessarily kick off an infection. However, if a fly has had time to really wander around on your dinner, you might want to eat something else, especially if you’re in the countryside.

The reason locales matter is they can influence just how dirty a fly’s feet are likely to be. Flies love things like feces, decaying corpses and rotting vegetable matter, as they provide both food and places to lay eggs. Contact with these items is where the flies pick up bacteria that they can carry back to you, and in general flies in urban areas have fewer encounters with dead animals and feces, unless your neighbor can’t pick up after their dog. You’ve probably seen a fly vigorously cleaning its eyes, wings and body, but until you can get them to use soapy water, that cleaning won’t eliminate the pathogens that you don’t want to eat.

Source: Cough it Up – Fly Vomit by Nancy Miorelli, Ask an Entomologist

On September 27th, 2017 we learned about

Sap beetles steal snacks from inside unsuspecting ants

Jet ants and sap beetles share a lot of similarities. Both insects depend on trails of pheromones to smell their way to their daily destinations. Both eat honeydew secretions obtained from aphids. Both depend on a regurgitation process to share that honeydew. However, all these commonalities don’t mean the two species always get along, mainly since the sap beetles do all this at the expense of the ants, occasionally triggering rapid, if slightly ineffective, retaliation.

Once a jet ant (Lasius fuliginosus) harvests honeydew from an aphid, it tries to carry it home in a special stomach called a crop. As with birds that regurgitate food for their young, the ants don’t digest the food kept in the crop so that it can be delivered “fresh” for friends back home. of course, the sap beetles (Amphotis marginata) have figured this foraging pattern out, and will hone in on the ants’ pheromone trails in order to intercept honeydew-laden workers for meals of their own.

When a sap beetle encounters an ant, it basically just walks up and requests a snack. Mimicking the movement of actual ants, the beetles tap the ant’s legs and antennae which prompts the ant to lick the beetle’s head. The beetles, as evolution would have it, secrete a liquid from their heads that scientists suspect confirms their ant credentials, allowing them to then force their mouth against the ant’s and wait to be fed whatever honeydew the ant was carrying home in its crop.

The beetles have a pretty high success rate, although they do have a plan ‘B’ if the ant catches on that it’s being tricked. They can pull all their appendages under their wing cover and flatten out against the ground. The ants can’t get at them under this protective shell, and are basically forced to move on to replace their stolen honeydew.

Putting numbers to the pilfering

To make sure these behaviors weren’t anecdotal evidence, scientists captured ants and beetles to more carefully track them in the lab. The honeydew was replaced with a sugary liquid doped with radiation that would allow researchers to trace exactly how much food was in each insect’s body, allowing them to quantify exactly how the ants and beetles interact. They found that the beetles truly have a kleptoparasitic relationship with the ants, doing nothing but stealing the ants’ food. In fact, beetles mooched off ants so well that they generally ate 1.8 times more food than ants relying on relayed sugar water. While it may seem like a one-sided relationship like this would be corrected by the ants, it’s possible that the beetles aren’t demanding enough food to force a change in the system. As long as the ants can still successfully reproduce, the beetles are an annoyance, but not necessarily an evolutionary pressure that will force them undergo radical change, like maybe learning what other ants look like.

Source: ‘Highwaymen’ beetles rob ants of the food in their stomachs by Mary Bates, New Scientist

On August 27th, 2017 we learned about

Ants float through floods by assembling into rafts and towers

As devastating as floods can be to human homes and infrastructure, they basically guarantee evictions for creatures that live underground. As water levels rise, insects like ants can’t lay down sand bags to keep their colony dry, but that doesn’t meant they simply drown. Ants in flood-prone areas around the world instead take advantage of their small sizes and large numbers to build themselves into means of escape, from amazingly durable rafts to living towers to scale new heights.

Floating with your friends

During a flood, a colony of ants will evacuate their underground tunnels and begin transforming themselves into rafts. With no executive planning, ants will rush out to the edge of the existing raft, then grab onto neighbors with their mouths, claws or foot pads. With enough workers, a raft of ants can support themselves, plus larvae and their queen that usually get to ride in the center of the raft for extra protection. Once assembled, an ant raft can hold together for weeks, even without individuals rotating positions within the raft’s structure.

The durability and buoyancy of the raft depends a lot on how hydrophobic ant bodies and hairs are. A drop of water on a fire ant’s head is likely to remain a single droplet, rather than breaking and wetting the ant’s whole body. As a group, this effect can trap significant amounts of air in the spaces between ants, to the point that a submerged ball of ants will carry air underwater with them in the process. Air bubbles trapped on ant body hairs can then be used for respiration and to increase buoyancy, keeping even 500,000 ants something approximating “dry” until they find solid ground to land on. If anything, the biggest risk of being in the water is fish, who can pick off ants that protrude from the edges of the raft.

Climbing as a colony

For all the resilience an ant raft provides its… members? (occupants?) it doesn’t work in every scenario a displaced colony might face. When ants find something solid and vertical, like a plant stem, they can start building themselves into a sort of bell-shaped tower. As with the rafts, each individual isn’t working with centralized directions, instead scrambling around to meet a couple of conditions as best it can: one ant can support up to three peers, if linked ants can’t surround the stem with linked arms, the tower needs more layers, and if you sink to the bottom of the pile, climb up again.

The squishiness of the towers means they’re not so much structures as much as processes. Tagged ants were tracked as they moved through the tower repeatedly, and it seems that the whole thing isn’t as static as a raft, but it’s enough to help ants reach new heights that might otherwise be inaccessible. Of course, if the surface of their new scaffolding doesn’t require a tower, they’ll skip it. People have found out the hard way that poking at ant rafts with an oar will very quickly lead to whole new set of unwanted passengers. Even though they can make their own rafts and towers, it seems that these ants are still appreciative of any assistance people can inadvertently offer until things dry out.

Source: How do fire ants form amazing towers and rafts without a master plan? by Craig Tovey, The Conversation

On August 23rd, 2017 we learned about

Lace sheet weaver spiders manipulate moths with their bright white webbing

The lace sheet weaver spider (Psechrus clavis) basically does what its name describes, although that’s really only half the story. Rather than messy tangle webs or circular orb webs, the sheet weaver makes a large, flat web that is usually suspended just over the ground, usually in shadier locales. It’s an unusual arrangement, especially since this spider likes to dine on flying bugs like moths, who presumably would be easier to catch mid-flight in a vertical web. However, experiments have found that the horizontal webs have a special property to help pull moths out of the sky.

As much as a horizontal web may look like a safety net, its success at snaring moths is probably due to looking like open space. Moths don’t have the greatest eyesight, and seem to navigate in the dark by making crude judgments about the amount of open space ahead of them. Having evolved in a world without artificial lighting, open space at night is generally going to be lighter than the dark silhouettes of trees, rocks and the ground. So when a moth is flying at your porch light, it’s likely very confused why this theoretically empty space is somehow solid enough to bang into.

Like the sky, only stickier

At some point the spiders stumbled upon this weakness in moth navigation, and can now use it against them. Their horizontal webs are notably bright and reflective, and researchers hypothesized that that white coloration looked light enough at night to convince the moths it was a safe place to fly. This was tested by covering a set of P. clavis webs in charcoal powder to make them dark black, then comparing how that new coloration affected the number of moths captured in a night. As suspected, the lighter webs caught a lot more prey, indicating that the white webs were more attractive.

The next step is to compare coloration to brightness. Some spiders make themselves, or their webs, look attractive with color for daytime hunting, but these nocturnal traps may instead be based on brightness. More tests are needed, but researchers want to now confirm if it’s the amount of light reflected, and not the specific white hue of the webs, that manages to convince moths that their final resting place is somehow a safe haven.

Source: Spider’s web uses optical illusion to lure nocturnal moths by Karl Gruber, New Scientist

On August 7th, 2017 we learned about

Honeybees can compare quantities from four down to zero

As bees fly through an area to look for nectar, they’re not just listening to their stomachs. Like a good explorer, they’re taking mental notes about where to find the best food supplies so that they can share the good news with the rest of the hive. Their assessments may be more than abstract judgments too, as honeybees have been found to be able to compare specific quantities between one and four. This allows bees to effectively count up to four flowers, on par with the capabilities of most dogs. New research has found that bees can take one big step further though, as they can also understand zero.

Selecting fewer shapes

To test how well bees could count, they were first trained to seek out smaller quantities. Images of different numbers of shapes were displayed at two feeding stations, with the lower number of shapes always being paired with a tasty sugar-solution. Higher numbers were paired with quinine to reinforce the pattern more quickly, and bees regularly flew to the correct, smaller quantity at least 80 percent of the time. What’s more, they were able to correctly compare quantities when the winning option showed no shapes. This may seem obvious, but understanding that “no shapes” is a quantity that can compared is a feat only seen in humans, chimpanzees and monkeys, all of whom have a lot more brain to work with than a tiny bee.

Few can make note of nothing

Understanding that zero is less than one may seem obvious, but that’s largely because you’re used to the idea that zero is a number. Zero wasn’t really recognized as a number until the fifth century A.D. in India, and managed to elude Europeans until the year 1200. Mayans also came up with zero in the first few centuries A.D., but it wasn’t innately part of human mathematics. This doesn’t mean that our honeybees are on the verge of working out multiplication or negative numbers (negative flower counts?), but it does shake our understanding of what kind of brain is necessary to handle a quantity of none.

At this point, it’s also not clear what bees might be counting. Keeping tabs on flower counts may be an option, although it may also be useful for tracking the dances bees perform to communicate their discoveries to each other. We know that bee brains can handle these operations, but figuring when they employ these math skills may be much harder.


My four-year-old asked: Why does zero matter?

This is a tough question to answer for someone still working on counting to 12. To start, it makes dealing with large numbers much easier, as we don’t need as many unique digits. We don’t need a character for ten because we can use 1 and a 0. Zero has also allowed us to deal with numbers less than one, including decimal fractions and negative numbers. It’s also critical for… oh wait, four-year-old.

Zero lets us keep track of amounts smaller than one, as well as work with much bigger numbers more easily. We’ll come back to this in a few years maybe…

Source: Bees are first insects shown to understand the concept of zero by Sam Wong, New Scientist

On July 12th, 2017 we learned about

Tomatoes infuse their leaves with toxins to turn insects against each other

Tomato plants do not want to be eaten. The 31 pounds of tomatoes each American gobbles per year is fine, because that helps with seed dispersal and gives us a reason to plant more tomatoes. The problem for the plants is that too many bugs bypass the red fruit and eat the leaves of the plant, leaving it with no way to produce its own food through photosynthesis. To defend themselves, the plants have found a way to control the bugs’ appetites and populations— they get the bugs to eat each other.

This pest-control concept is actually based on normal behavior in various pest herbivorous insects, like mottled willow moth caterpillars (Spodoptera exigua). When these bugs can’t get enough nutritious food, they don’t really have the means to travel to find something better, as they’re trying their best to hoard calories in preparation for metamorphosis. So when the leaves are scarce, or just low enough quality, the insects will start eating each other instead as the last local source of nutrients and calories.

Turning up the toxins

Tomato plants (Solanum lycopersicum) have evolved to exploit this quirk of pest ecology. Tomatoes in danger can start producing extra toxins in their leaves that make them less nutritious to eat. Manipulating leaf-quality like this then convinces caterpillars it’s time to switch to cannibalism. In experiments, caterpillars offered more toxic leaves started munching caterpillar corpses much sooner than their peers. From the tomato plant’s perspective, adjusting the chemistry of leaves may be energetically costly, so they don’t make their leaves less attractive all the time. When circumstances demand it, this strategy does work well enough to make a measurable difference in just how much each plant gets eaten.

The last layer of this defensive strategy is that a tomato plant doesn’t need to get bitten to start raise its defenses. Like a variety of other plants, tomato plants can warn each other about the arrival of herbivores. They emit a compound called methyl jasmonate (MeJA) that can be detected by nearby plants, giving them a chance to start toxifying their leaves before the insects begin their buffet. There is some interest in manipulating this warning system, since presumably farmers could release MeJA to warn crops whenever they wanted. However, it might be best to follow the tomato plants’ lead on this, since constant warnings and toxic leaves could stress the plants while selecting for only the hardiest, toughest insects around.

Source: Plants turn caterpillars into cannibals by Laura Castells, Nature

On July 4th, 2017 we learned about

Engineers look to Lepidoptera for lessons on manipulating light

Butterflies and moths are masters of light manipulation. Their bodies have evolved specialized structures that allow them to reshape light in ways we can, at this point, only envy. Researchers are doing their best to emulate them though, building new materials based on molecular structures found in these insects’ wings and eyes. With any luck, we’ll soon have new ways to bend and trap light, improving everything from the ways we cool our buildings and stare at our screens.

Skipper butterflies in the family Hesperiidae might not have the saturated oranges or blues of other species, but small flecks of white on their wings have been catching researchers’ eyes. As with blue, there’s no pigment that makes the wings white. To send white light to your eye, the butterfly’s wings are instead covered in tiny scales that are bent or twisted at different angles to control how the light is refracted. The angle of each scale then plays a role in the color produced, which can apparently be manipulated in a why a static pigment can not.

In the case of skipper butterflies, the white dots on the outside of their otherwise brown wings can display more than one color of white. Close examination found that these spots seem to be a key signal to other butterflies, and their wing scales can control just how reflective or dull the white appears. The degree of control can even very between being dependent or independent on the viewing angle of the wing.

This kind of control would be great to build into various technologies, starting with glass and paints. Since white light is made up of all the colors from the visible spectrum, reflecting white light is a good way to keep sunshine off an object. People in hot climates often paint roofs white to try to keep buildings cool, a strategy that could be greatly enhanced if the paint could incorporate some of butterfly scales’ light-bending properties.

Seeing more with less light

Sometimes reflecting light isn’t what you’re looking for. In those cases, moth eyes may provide a good model for how to bend light in order to trap it. Moths evolved specialized structures in their eyes to help keep them from reflecting ambient light at night, which might make them visible to predators. Human eyes really only experience this a problem when a camera flash goes off, but the underlying principles may be very helpful in the design of LCD screens, like those found on your phone.

When light hits the glass of your phone, some of it is reflected back at your eyes. When it’s coming from a source brighter than the screen, like direct sunlight, it can overpower the image the screen is trying to show you, leaving you nothing to see but glare. To compensate, devices crank up their screen brightness, but that takes a lot of power, draining your battery faster. With a moth-inspired film on the outside, the sunlight wouldn’t be reflected, and the screen could remain dimmer without a problem. Engineers are hopeful that this will be available to phone manufacturers soon, but some issues like durability are still being worked out. For all their subtle ways of controlling light, moths and butterflies aren’t the most rugged insects out there.

Source: Penn collaboration produces surprising insights into the properties of butterfly wings

On June 25th, 2017 we learned about

Pulsing lights can make mosquitoes miss their meal times

In a battlefield strewn with netting, pesticides and other deterrents, people’s fight against mosquitoes may soon be aided by some new lighting, and the mosquitoes’ own brains. As with many inter-species conflicts, there’s long been an arms race between humans and mosquitoes, with each new defense being challenged and possibly potentially defeated as one side makes small adjustments against the other. For humans, this has meant adding pesticides or repellents to mosquito netting over our beds, but in many parts Africa those tools are being undermined by hungry Anopheline mosquitoes that have learned to wait until we’re out of bed. Still, this attentiveness to a schedule has opened the door to another line of defense— the circadian rhythms that tell us when to sleep, and the mosquitoes when to eat.

Dining in the dark

Anopheline mosquitoes prefer to do their dirty work in the cover of night, getting a lot of their feeding done in the low-light of early morning and the late evenings. Mosquito netting helps keep the insects off sleepers, but if the female mosquitoes wait a person out by feeding in slightly brighter light, netting can only do so much. To develop a non-chemical way to keep the bugs away from people for other parts of the day, scientists started experimenting with resetting the mosquitoes’ internal clocks with carefully-timed lights. If successful, this would essentially confuse the insects enough to miss their optimal feeding times, making their survival much more difficult.

Two experiments were conducted in dark chambers full of mosquitoes. The control group was kept in the dark, while the experimental group was exposed to ten minutes of pulsing white light. When offered a volunteer’s arm to munch on, the insects that had seen some pulsing light were much less likely to feed or even attempt to fly. In a follow-up, the experimental group of mosquitoes was exposed to pulsing light every two hours over a 12-hour night, and their behavior remained altered for four hours afterwards, meaning they weren’t ready for a normal feeding schedule until well after they’d normally eat.

Sensing light to set a schedule

The idea that brief exposure to flashing lights can reshape one’s behavior has been established in other animals already, including humans. While our eyes and brains evolved around the gradual change in light from sunrise to sunset, it turns out that even brief flashes of light can change when we feel awake, hungry, sleepy, etc. These carefully-timed pulses stimulate special ganglion cells in the eye, which then inform our suprachiasmatic nucleus, which then helps govern things like melatonin production so that we feel sleepy at night. In people, adjusting our light intake can enable manipulations to your daily sleep schedule, but for the mosquitoes it means missing feeding hours entirely.

Knowing such a disruption is possible, researchers hope that lights could be used at night to stop mosquitoes from feeding on sleeping humans. While white light was used in these first experiments, other ranges of light are going to be tested, in case they’re still effective while being less disruptive to people. Either way, if flashing lights can reduce the number of mosquito bites people receive, it should help with the larger goal of slowing the spread of dangerous diseases, like malaria or the zika virus. This probably wouldn’t neutralize mosquitoes forever, but it would be a chemical-free way for a lot of people around the world to sleep easier each night.

Source: Researchers use light to manipulate mosquitoes by Jessica Sieff, Notre Dame News

On June 13th, 2017 we learned about

Assessing the imagined ferocity of several local insect species

According to my kids, our street is on the verge of being inundated in dangerous insects. My four year old has warned me that “if you step on a pincher bug, it will bite your foot!” which… well yeah, most animals try to defend themselves if you step on them. So what vicious mandibles were my kids and their friends uncovering? The pincher bugs turned out to be earwigs, with a few cameos from silverfish (or maybe a firebrat.) Since these creatures really only pose threats to aphids, cardboard and old book bindings, it seems that our suburban street is still as tame as you’d expect it to be.

Encountering earwigs

To be fair to my kids, earwigs (Forficula auricularia) are probably the most intimidating-looking insect in this group. Their abdomens carry curved appendages technically known as forceps, but that have the visual panache of a bug-sized antler crossed with a claw. Since they’re on the abdomen, these forceps can’t really deliver a bite, but a larger male earwig could possibly give you an uncomfortable pinch if you scared it (or stepped on it.) The forceps are more often used to fight with rivals over potential mates, like the hardware on stag or Hercules beetles, and as such are generally larger on male than females.

The name “earwig” of course confuses people’s understanding of these bugs’ ecology. Anecdotes of burrowing into ears aside, the name is most likely the result of a misunderstanding of the name “earwing.” This name would have been much more descriptive, since these aphid-munching creatures have little interest in ears, but do have unusually shaped wings. The only way these bugs do make themselves a problem for humans is when they can’t find their preferred food and attack plant roots in a garden rather than assaulting humans.

Spotting silverfish

A few members of the Zygentoma order have also been found around our house, more commonly known as silverfish (Ctenolepisma longicaudata). These ancient insects can scuttle around at impressive speeds, flattening their bodies out to squeeze through tight spaces where they prefer to stay out of sight. They’re not great at climbing though, which is part of why you find them stuck in smooth-sided containers like your bathtub or a certain kid’s toy bin. They lack any appreciable claws or spines, and, despite some rumors to the contrary, can’t cause harm to you (although your belongings might not be so lucky).

One of the neat things about a silverfish is that they can go months at a time without eating. However, in the average American household, they don’t have to worry much about that thanks to people stocking their houses with papers, glues, cardboard, pastas, as well as veggies and bits of mold. Eating mold probably won’t raise any complaints, but people do run into problems with silverfish eating the starch around the house, which can lead to damaged books, stolen dry food, or holes in clothing. If you have spiders around though, they’ll probably help keep your silverfish populations in check.

Finding firebrats

While silverfish appreciate moist locations, their firebrat relatives prefer heat. Firebrats (Thermobia domestica) basically copy a lot of the silverfish lifestyle, but do it closer to your hot water heater, furnace or other hot spots around the house. Looking like a striped version of a silverfish, they’re equally harmless to people, but also potentially hazardous to books, glues and other starchy objects.

So I think between this collection of creepy crawlies, plenty of craneflies, daddy long-legs, a few black widows plus wasps and bees, it’s probably still safe to let the kids play outside. If we can keep the mosquitoes at bay, we may even survive the summer.

Source: Earwig invasion! Pest inundating gardens eats your fruit -- and those nasty aphids too by Jeff Spurrier, LA at Home