Bug Eric

Yes, the image below is of a crane fly in the family Limoniidae, but what is that other thing attached to it? The crane fly showed up at our backyard blacklight a few nights ago in Colorado Springs, and by itself would have been interesting. Its hitchhiking companion made it even more spectacular.

Pseudoscorpions are tiny arachnids, most of them under five millimeters in length, that never fail to provoke head-scratching among people unfamiliar with them. They look like they could be baby scorpions that are missing their telson ("tail"), but they are literally in an order unto themselves: Pseudoscorpiones. They are fairly common, but seldom seen because they frequent microhabitats under bark on trees, stumps, and logs, or leaf litter or topsoil, or in mammal nests or caves, or other places that require a dedicated effort to uncover them. It is only those species that occasionally turn up in our "caves" (homes) that catch our attention.

I wrote about pseudoscorpions previously, for Missouri Conservationist magazine, thanks to fantastic photographs by Ashley Bradford and Ted MacRae, but this week's find finally allowed me my own imaging opportunities. It is interesting that the insects favored as transportation by pseudoscorpions are frequently those associated with decaying wood: longhorned wood-boring beetles (Cerambycidae), braconid wasps that are parasites of wood-boring beetles, and in this case a female crane fly which I would bet oviposits (lays eggs) in decaying wood.

Pseudoscorpions are predatory on other small invertebrates such as springtails, barklice, fly larvae, and mites. They seize their prey with the pincer-like chelae at the ends of their "arms." Those heavy, muscular appendages are actually modified mouthparts called pedipalps. Many species of pseudoscorpions have venom glands in the chelae that help subdue struggling victims. From there, the prey is passed to the plier-like chelicerae, or jaws, that puncture the body wall of the prey, or crush it, and allow for the introduction of regurgitated enzymes to begin the extraoral digestive process. The resulting liquified material is then ingested by the pseudoscorpion.

Bizarre? We are just getting started. The chelicerae also house silk glands, and pseudoscorpions spin silk to encase clutches of eggs, for shelter during molting and overwintering, or even as a retreat from which they can wait in ambush for unsuspecting prey to pass within reach.

Using another animal for transportation is a behavior called phoresy, and that appears to be the chief means of dispersal for pseudoscorpions. They do not have wings, after all, and are so tiny that getting from one optimal niche to another under their own power is almost impossible. Also, they do not "balloon" as many spiders do, spinning silken threads that are caught by the wind and waft the spider to a new home.

After the crane fly died, the pseudoscorpion disembarked and I was able to get the images you see here. I discovered they are much more agile than I anticipated. This one could scuttle backwards fairly rapidly, run forward quickly, and it could easily climb the slick walls of our casserole dish "studio." Maneuvering the tiny creature with an artist's paintbrush was challenging since the animal could simply grip a single bristle and refuse to let go.

The social life and love life of pseudoscorpions is surprisingly complicated. Members of some species can live side by side without antagonizing each other, displaying unique and rhythmic movements of their bodies and/or pedipalps to communicate. Meanwhile, courtship between male and female in nearly all species is accomplished through a variety of behaviors. In all cases, the male packages his sperm in a spermatophore. In the most primitive scenario, he simply deposits on the ground or other substrate where he hopes a female encounters it. She will then pick up the spermatophore in her genital opening.

Males of other pseudoscorpion species will only deposit a spermatophore if they encounter a female. These males may then spin a simple or elaborate, three-dimensional silken bower to help funnel the female to the location of the spermatophore. This greatly improves the male's chances of reproductive success.

Mating can be more intimate in the most "advanced" species. This involves what is best described as dancing, the male grasping the female's pedipalps in his, and gently but firmly guiding her over the spermatophore he has just deposited. There may be subtle choreography and pre-programmed body movements involved in that. They may even kiss, if you will, interlocking their chelicerae.

Despite the extent of our collective knowledge of pseudoscorpions, new species are discovered with a surprising degree of regularity. Those who study caves and other specialized habitats; and those who study rodents and other vertebrates, would be wise to keep their eyes out for pseudoscorpions. Meanwhile, carefully inspect the insects at your porch light and you might eventually find one of these arachnids on an insect attracted by your beacon.

Sources: Johnson, Elizabeth A., and Kefyn M. Catley. 2002. Life in the Leaf Litter. New York: American Museum of Natural History. 28 pp.
Weygoldt, Peter. 1969. The Biology of Pseudoscorpions. Cambridge, Massachusetts: Harvard University Press. 145 pp.

It has been difficult to build-up enthusiasm this summer because insect abundance is way down here in Colorado Springs, but when I get to witness an event like I did yesterday, it makes me glad I went out and made an effort.

I happened to glimpse a very odd, fairly large insect out of the corner of my eye. It took me a minute to realize it was not a single insect, but two: a female Ammophila sp. thread-waisted wasp toting a caterpillar she had paralyzed. She was trying to locate the concealed nest burrow she had excavated before going hunting, and was wandering around rather aimlessly, but at high speed.

At one point she cached the caterpillar so she could orient herself without such a burden. It worked. She found her burrow, then went back and got the caterpillar. I was lucky to get any images of the transport because she moved so speedily and kept going in and out of focus. Even an attempt at video may have been almost useless. Her agility, with such a heavy load, was impressive. It would be like you or me running at full speed carrying a sofa between our legs.

She abruptly dropped the caterpillar, and in a matter of seconds uncorked the stone plugging her nest burrow. She quickly entered her burrow, turned around inside, and re-emerged to grab the caterpillar and pull it in. She has to be this fast to avoid tiny parasites known as "satellite flies" that will lay tiny maggots on the caterpillar before the wasp can get it secured underground. Indeed, there was at least one miltogrammine fly flitting at the entrance to the burrow.

About a minute or so passed with both the wasp and her caterpillar underground. Finally, she emerged topside and quickly retrieved the stone that had plugged the burrow opening previously. She replaced the stone and began kicking sand on top of it. Notice how she curls her front "feet" to maximize the tarsal rake of spines that aid her in digging and filling. At one point she was startled by a curious ant and took to the air for a spit second. Ants can raid wasp burrows and cart off the caterpillar and wasp egg as food for their own young back at the colony.

By now I was getting a bit stiff from having stood in the same place for a long while. When I left the wasp, she was apparently unsatisfied with the nest closure and was actively chewing down to the rock plug. I left her in peace to finish what she had started.

The whole sequence of events involved in the provisioning of a nest by a solitary wasp is truly remarkable. She has to dig her burrow and, load after load, flies off with armfuls of soil to fling across the landscape, lest some predator or parasite recognize her nest from piles of "tumulous" around the opening. Next, she fills in the burrow entrance, obliterating all evidence of any cavity whatsoever. She may make a brief orientation flight and then go off to hunt. How does she ever find the burrow again? We cannot even remember where we parked our car, or left our cell phone, and we reportedly have much larger brains than wasps do.

Once she has completed her mission of providing one paralyzed caterpillar for a single offspring, she goes off to start the process all over again, somewhere else. Does the wasp immediately forget about the burrow she just completed? How does that instinct work? It has to be plastic enough to address unique situations and overcome obstacles.

Over the coming months, in that underground cell, a wasp larva will hatch from the egg and begin consuming its still-living but inactive larder. Scientists believe that insects have no pain receptors, so that must be a blessing to the caterpillar. Were it deceased, though, the caterpillar would quickly rot under the assault of bacteria and fungi. After consuming the caterpillar, the wasp larva enters the pupa stage, as equally inert as the caterpillar on the outside, but inside the pupa there is a massive reorganization of cells converting the grub-like larva in to a sleek, winged adult wasp. Some genes are turned on, others are turned off. It is amazing to contemplate that a wasp larva, or caterpillar, has inside it the latent ability to execute all the behaviors of the adult. It somehow "knows" it cannot fly, does not need flower nectar, and cannot reproduce as a larva. It understands at some fundamental level that its only job is to eat and grow.

The next time you are out hiking, and a wasp flies up from under your feet, stop for a second. Back up a little. Does the wasp return to the vicinity? If so, keep watching. She is probably in the process of working on a nest burrow and will resume her activities if you stand still. It takes a little practice just to think about this possibility, but the rewards can be astonishing.

The insect world is full of drama, one of the major attractions for entomologists and naturalists and wildlife photographers. Among the more rarely-witnessed phenomena are raids by slave-making ants in the genus Polyergus, known as "Amazon ants."

I have had the privilege of seeing three separate slave raids while living here in Colorado Springs, Colorado. All have taken place in late afternoon or early evening. The latest was on July 1 of this year when my wife and I were hiking a trail in Cheyenne Mountain State Park. She happened to pause at what I initially dismissed as yet another harvester ant trail, worker ants bustling about with grass seeds.

The ants were actually carrying the pupae of their host, ants in the genus Formica. We traced their apparent destination to a Formica colony, but I have learned that this makes sense. The adult slaves on the receiving end of this raid represent members of a colony taken over by an Amazon queen that managed to dupe the workers of an existing Formica colony before killing its queen. Those workers will now set about rearing these most recent arrivals, "adopted" larvae and pupae.

The anatomy of Amazon ant females is such that they are obligatory warriors. Their bodies are sleek and shiny, their slick exoskeletons deflecting the attempted bites of their victims. The jaws of Amazon ants are sickle-shaped and designed to do only one thing well: pierce the heads of the worker Formica ants. Amazons cannot feed themselves, let alone excavate a nest, so they must depend on existing subterranean nests of their Formica hosts. The Formica workers at the receiving end of the Polyergus raid were already enslaved!

The efficiency of a Polyergus slave raid is stunning. One wonders if the victimized colony, pilfered of most of its juvenile workers, ever recovers from such devastation. These ant pirates show now mercy, except for the kidnapped larval and pupa offspring, the majority of which they somehow manage to transport without injury. Not that some of these soft-bodied juveniles will not end up as food instead of slaves, mind you.

How this specialized lifestyle came to be is open to conjecture, though a reasonable theory comes from studies of ant evolution and genetic relationships. There are slave-making species in the genus Formica, some of them obligatory slave-makers, and others facultative. Facultative social parasites are species capable of existing and prospering in the conventional sense, but are also opportunistic slave-makers. It is surmised that Polyergus Amazon ants evolved from the obligatory slave-making Formica species. Indeed, they appear closely related.

An average colony of Polyergus is between 300-500 workers, surrounded by many hundreds of their slaves. Such a colony can include a mix of different Formica species. Raids on Formica colonies are frequent, and so Amazons need a robust population of host colonies that they can draw from.

The genus Polyergus is holarctic (found throughout the northern hemisphere), but reaches its zenith of diversity in the United States. There are fourteen species in the world, eleven of which are found only in the U.S. Polyergus mexicanus is likely the one I have been seeing here along the Front Range of the Rockies. Ant diversity in general is surprisingly great here in Colorado, so it is easy to assume you are only seeing a few species when in fact there are several.

Keep an eye out for interesting ant behaviors, and try and document them as best as you can. You could shed new light on our collective knowledge of these amazing social insects.

Sources: Anonymous. 2017. "Polyergus,"Antwiki
Holldobler, Bert and E.O. Wilson. 1990. The Ants. Cambridge, Massachusetts: The Belknap Press of Harvard University Press.732 pp.

Please do not let the title of this post intimidate you. This would be a typical title for a paper in a scientific journal, but I promise to keep the language understandable, lively, and captivating. I also hope that you will be more likely to visit scholarly publications to learn more about the insect or arachnid subjects that interest you.

I had the good fortune of stumbling upon a small sawmill in Black Forest, northeast of Colorado Springs, in June of 2016. The property owners, perhaps begrudgingly, gave me permission to look for insects in the stacks of Ponderosa Pine logs there, and it proved to be a "Beetle Bonanza." I visited on several occasions and found scores of jewel beetles (Buprestidae), longhorned beetle (Cerambycidae), checkered beetles (Cleridae), and a few bark beetles (Curculionidae: Scolytinae).

Among the more abundant species among the logs was the White-spotted Sawyer, Monochamus scutellatus. These are fairly large insects, 15-27 millimeters in body length, and members of the longhorned woodborer beetle family. The long "horns" refer to the antennae of these beetles. Males have antennae that may be twice the length of their bodies or even longer. The front pair of legs is also longer than in the females, and the front tarsi ("feet") are expanded to better grip the female during mating.

What I observed in one pair of sawyers prompted me to read about the mating behavior of the species, if only to confirm my hypothesis that the male guards the female he has mated with to prevent rival males from usurping his genetic investment in her offspring. It turns out there is even more to the story than I imagined, and I hope to observe those other behaviors at some point, too.

White-spotted Sawyers breed in dead, dying, injured, fire-scorched, or recently-felled pines, true firs, and Douglas fir, and spruce. Such resources are rather scarce in a forested landscape, so it pays males to stake them out with the understanding that eventually females will visit in order to lay their eggs (oviposit). Surprisingly, the males emit a pheromone that draws additional males to an oviposition site. The airborne chemical cue is called an "aggregation pheromone." Despite their size and ungainly antennae and legs, sawyers are accomplished fliers and easily make their way to the source of the pheromone.

Once there, the largest males with the longest antennae may square off in one-on-one duels for possession of the oviposition resource, which is the area of the tree trunk with greatest circumference. They lash at each other with their oversized antennae, and may grapple by locking their jaws and biting. Smaller males generally back off, giving way to larger rivals based on antenna-length alone. The dominant male mates with incoming females that may then disperse to lay their eggs. This is not what I observed, but the reference I am reading goes on to describe what I did record.

I witnessed copulation between a male and female M. scutellatus, during which time the female was "multi-tasking," chewing a small cavity in the bark. At the conclusion of mating, the female turned around to deposit at least one egg in that cavity while the male continued to grasp her in a loose but protective embrace. She then turned again and appeared to resume chewing the bark cavity, but perhaps she was grinding sawdust to cover her egg.

Fret not about the smaller male beetles, they may achieve mating success by protecting a less optimal tree bole; and they may profit from the expensive production of aggregation pheromone by other males. Smaller males are usually more agile and vigorous than their larger conspecifics.

The entire life cycle of the White-spotted Sawyer takes from one to two years as the larva that hatches from the egg bores first under the bark, then tunnels deep into the wood, sometimes reaching the heartwood. It eventually pupates in a cell near the surface, metamorphosing from a larva into an adult beetle. Once it leaves the pupa, it remains in the pupal cavity while its new exoskeleton hardens. It then chews its way to freedom, a journey that is clearly audible to the human ear.

It is important to note that this species, like the overwhelming majority of other longhorned beetles, is not a forest pest. Yes, it can negatively impact logs in situations like the sawmill, before they are cut, but they do not kill living trees outright like the invasive Asian Longhorned Beetle, Anoplophora glabripennis. Sawyers are an important and charismatic part of the invertebrate fauna in coniferous forests across Canada and the northern U.S., and major mountain ranges farther south.

Sources: Coin, Patrick. 2004. "Species Monochamus scutellatus, Whitespotted Sawyer," Bugguide.net
Furniss, R.L. and V.M. Carolin. 1977. Western Forest Insects. Washington, DC: U.S. Department of Agriculture Miscellaneous Publication No. 1339. 654 pp.
Wang, Qiao (editor). 2017. Cerambycidae of the World: Biology and Pest Management. Boca Raton, Florida: CRC Press. 628 pp.

In service to my colleagues who have waning patience as they are bombarded with the latest social media sensation, I offer this explanation to the moth with the "tentacles" coming out of its posterior. Here is the circulating image, but there is also a video that is associated with most Facebook posts.

Ok, first things first. This moth is Creatonotos gangis, an arctiine (tiger) moth from southeast Asia and Australia. The specimen shown is a male. He is everting his androconial glands or coremata (Greek for "feather duster"). The glands are normally concealed within his body, and are inflated at will by air pressure or blood pressure. Less dramatic versions of these organs are known as "hair pencils." Usually concealed within his abdomen, the coremata are deployed when he is seeking acceptance by a mate.

Wait, you thought female insects were the ones using pheromones (scents used mostly to attract the opposite gender, but with other functions, too, especially in social insects)? Well, me, too, so I did a little digging. Turns out that the male's sexual chemicals are not meant for long-distance attraction of females, but to communicate his "fitness" as a mate. So, the products of androconial glands have been likened to aphrodisiacs, tranquilizers, or narcotics, aimed at seducing the female. Ok, but how? It is a long story....

As caterpillars, many tiger moths (subfamily Arctiinae of the owlet moth family Erebidae) feed on toxic plants. Milkweed is a good example. The plant is packed full of cardiac glycosides, potent poisons intended to discourage herbivores, including caterpillars, from consuming it. Not only are some caterpillars able to overcome the toxicity, they incorporate it into their own bodies to make themselves toxic to their predators. This is called sequestering, and the commandeered poison stays with the insect throughout metamorphosis and into adulthood. One of the byproducts in male moths is the pheromone emanating from those androconial glands. He thus demonstrates to the female that he is genetically superior based on a greater quantity of accumulated toxins that she can then pass on to her offspring.

This is a relatively dry explanation of these remarkable structures in male tiger moths. You owe it to yourself to be better entertained and further enlightened by an article in Wired magazine by my good friend and colleague Gwen Pearson. Even the graphics are better, and a GIF has never been funnier, at least in the context of entomology.

So, far from "terrifying" as a similar viral graphic was labeled in a headline from Huffpost, these glands are an amazing example of evolution, just like elk antlers and other male adornments. Please share the fascination, without the sensationalism. Thank you.

My last post here chronicled predation on termites by ants in the wake of swarming events in my neighborhood. Today I shall turn the tables and demonstrate that ants are not immune to predators themselves. Antlions and tiger beetles are among the few predatory insects that kill and eat ants. Ants can bite, and either sting, or spray formic acid to defend themselves. One cannot blame a potential predator for avoiding that kind of trauma when ants are not much more than an hors d' oeuvres anyway.

While looking for tiger beetles in Lake Pueblo State Park, Colorado on March 18, I was surprised to find the funnel trap of an antlion larva in the middle of a game trail. Usually, the pitfall traps of antlions are clustered, and situated in sheltered areas like beneath a rock overhang, at the base of a tree, or other location where rain seldom if ever reaches them. Since the only genus of antlions in the U.S. that makes such traps is Myrmeleon, I knew that had to be the critter lurking at the bottom of the pit.

Buried just beneath the dusty sand was a single, chubby larva, studded with spines on various parts of its body, and with menacing sickle-like jaws. Nearly blind, the insect relies on its sensitivity to vibration to detect potential trouble or potential prey. When an ant or other terrestrial insect blunders into the antlion's steep-walled trap, the larva becomes alert and proactive. It may use those jaws to fling sand onto its victim, hastening its descent to the bottom of the funnel. The predator then grabs its prey and injects it with enzymes that paralyze it and begin the digestive process.

Antlions go through complete metamorphosis, so the larva eventually constructs a cocoon of sand and silk in which it pupates. An adult antlion, more than making up for its youthful ugliness with its delicate wings and slender body, emerges from the pupa at a later date.

The fate of ants in the jaws of an antlion may seem morbid, but it is still better than what happens to ants caught by adult tiger beetles. After two consecutive days of unsuccessful searching for tiger beetles closer to home in Colorado Springs, I finally found at least three Blowout Tiger Beetles, Cicindela lengi, on the afternoon of March 23. I was witness to their ability to swiftly dispatch lone worker ants with their huge, toothy jaws.

Most tiger beetle species are agile daytime hunters that haunt sandy habitats like the sandhill bordering the vacant lot where I found these specimens. The insects run quickly, stop, then run again. They fly a short distance if spooked by a potential predator. Their eyesight is keen, vastly more sensitive to motion than a person; but they focus slowly. They literally outrun their eyesight when pursuing prey, and must stop to refocus before rejoining the chase. This herky-jerky hunting strategy is still effective, and few insects spotted by a tiger beetle will live to tell the tale.

Tiger beetles appear to have the speed and power to attack insects and other invertebrates at least as large as they are, but most of their victims are quite small. Ants seem to be near the limit of what they will take. They make short work of even the feisty Western Harvester Ants, Pogonomyrmex occidentalis, that are abundant in Colorado Springs. The jaws of the beetle quickly dismember the ant, leaving a trail of carnage around the beetle. The beetle's next victim may be a tiny, unidentifiable invertebrate it plucks from between sand grains.

Most tiger beetle enthusiasts are fond of remarking that they are glad tiger beetles do not get any larger in size than they do. Indeed, I would not be prowling around dunes and beaches if there were even raccoon-sized tiger beetles in the neighborhood. Since they are much smaller than that, I recommend going in search of them. Their beauty and behaviors are sure to capture your curiosity and sense of wonder.

My neighborhood walk in Colorado Springs the other day, March 25, was like strolling through living confetti at some points. All the local termite colonies were launching swarms of winged males and potential queens (alates as scientists call them). The frail creatures were not ignored by other animals, either, especially ants. Closer inspection of the swarms revealed three species of ants preying on them.

Termite swarms are not an indication of the impending collapse of your home or any other wooden structure. Yet, that is the first thought that enters the mind of the average person witnessing the spectacle. Such is the power of advertising for pest control companies. Now, a termite swarm inside your home should probably be cause for alarm. Outdoors, subterranean termites like these Reticulitermes sp. are vital to the recycling of decaying wood. They nest in the soil, as their common name suggests, and forage for wood and other dry cellulose in contact with the soil.

The synchronous nature of termite swarms is a marvel. All colonies in a given area need to liberate their reproductive castes at the same time in order to prevent inbreeding, but I have no idea how they "decide" when to do this. The day before we had snow and high winds. The alates issue from the tiniest of cracks in the soil, like toothpaste from the tube, the better to avoid easy detection. Eventually, enough of the insects appear that their gauzy wings reflect the sun and give away their presence. Soldier termites, and workers, too, escort them out and see them off.

Hundreds, if not thousands, of winged termites begin filling the air. Few will survive the alert eyes and hungry mouths of birds, lizards, and other predators. The early season timing of swarms may in fact be tuned to precede the emergence of reptiles and the arrival of migrant birds. Ants, on the other hand, are already on the prowl.

Both ants and termites are social insects, so it is fitting they would be deadly enemies and, one would think, well-matched foes. Watching one swarm happen on the edge of a driveway, I began noticing the appearance of worker ants, Formica sp., crossing the driveway. Eventually I saw one toting a winged termite back to the nest. The ant's nest. More ants followed suit.

Turning my attention back to where the termites were emerging, I noticed something even more frightening. Tiny "pavement ants," Tetramorium sp., were killing both alates and worker termites right at the termite nest opening. Whereas Formica ants are a bit larger than the termites, the pavement ants were smaller than their prey. How they avoided the menacing jaws of the soldier termites confounds me.

Just up the street I noticed heavy ant activity originating at the base of a brick-and-mortar mailbox pillar. These were Formica pallidefulva ants, but appeared larger than the other ones I saw previously. It soon became apparent that they were also taking part in the Great Termite Massacre of 2017. Most of them were carrying wingless alates, though.

Alate termites, once paired, shed their wings easily. Both pairs of wings have a weak spot that allows the termites to break them off so they can quickly seek cover. The male ("king") termite follows on the heels of his mate (queen) as they form a two-car train in search of a potential nest site. They must do so quickly if they are to avoid the marauding ants.

Whether the honey pot ants were taking dealate (wingless reproductives) termites, or just seizing winged individuals and breaking off their wings, remains a mystery. They are certainly easier to transport without those cumbersome wings.

As I turned the corner to go home, I caught sight of yet another ant, possibly Formica podzolica. It, too, was carrying a defeated termite. The ant seemed at least somewhat disoriented, and I eventually lost track of it in the thick grass at the edge of the curb.

So, termites are both integral to keeping soils fertile with their decomposition activities, and also a bounty for many other organisms that depend on them for food when other insect life is less plentiful. Ants are the lion kings and wolf packs of the macroscopic landscape, keeping termites and other insects from overrunning the planet. The ants are not immune, though, and in my next post we see them on the other end of the predator-prey equation.

Note: Special thanks to James C. Trager for identification of the ant species.

At some point in their career, every entomologist will be asked the question "do insects feel pain?" A surprising amount of research has gone into answering that question or, in some instances, unrelated research has provided insight into that query. My answer to that question has more to do with the person asking it, and as far as I know, that is a unique response.

As one who interacts with the public more than many entomologists, it has become evident that while some people have no qualms about ending the life of an insect, even advocating extremely inhumane techniques ("Kill it with fire!" is a common reply to someone else's social media request to identify a household insect), there is an increasing tolerance for insects, even in the home. If the creature is unwelcome, there is now often a plea for a non-lethal means of dealing with the uninvited arthropod.

The flipside of this more empathetic response to "bugs" is the question of whether insects feel pain. The obvious, hoped-for answer is "no, they don't." The person asking is then relieved of guilt for harming or killing any insect in the past, present, and future. So, while the new trend is for more people, especially women, to seek humane methods of insect control, many people still look for examples of how insects do not deserve empathy and compassion as a way to vindicate their own behavior towards other organisms.

The bottom line in the question of whether insects feel pain is thus the unspoken question of whether killing insects and spiders falls into the category of cruelty to animals. Legally, it would be difficult to argue that insects, being animals, are exempt from that crime. Obviously, this is not the case, and I do not see that implied public consensus changing anytime soon. Swatting a mosquito could be an act of "self-defense," though, considering the atrocious diseases that those biting flies can transmit.

Ok, so you want a scientific answer? Most entomologists I know resort to the short answer that insects do not have "pain receptors" like higher animals. This means they have no nerve cells devoted to the perception of pain. Insects can sense heat and cold, for example, and various chemical and tactile stimuli, but not pain as we would define it.

The fact that many insects, and other arthropods, willingly sacrifice limbs and other body parts in order to survive predator attacks is a testament to how apparently immune to pain they can be. A missing leg hardly slows down a grasshopper. Tattered wings rarely encumber a butterfly finishing its mission of mating and procreation.

As a colleague and fellow blogger noted in his own treatment of this question, another important aspect of physical pain is the emotional distress that comes with it. Ascribing human emotions to non-human organisms is known in the scientific community as "anthropomorphism," and is considered a big no-no when attempting to conduct unbiased research and observations. So ingrained is the concept of avoiding anthropomorphism that we now have to question whether the unemotional conclusions we draw in animal behavior studies are really the correct ones. The truth probably lies somewhere in the middle.

The fact that people are asking questions like this that leave open the possibility that insects and other arthropods are sentient beings is a hopeful sign, regardless if that belief is based in reality. We could certainly stand a little more empathy for other living things. Then again, look how we treat other members of our own species.

Source: Ballenger, Joe, 2016. "Do insects feel pain?," Ask an Entomologist.

During the heat of summer, we all perspire. Some insects find that bodily function irresistible. Among them are sweat bees, various flies, and even butterflies. It is believed that the salts, minerals, and other compounds in our sweat are necessary for these insects, and difficult to find elsewhere. While you might assume that any insect landing on you intends to bite or sting, rest assured these insects are harmless.

Solitary and semi-social bees in the family Halictidae are collectively known as "sweat bees" because of their habit of lapping up human sweat with their short "tongues." They may tickle at most, but if you smack one absent-mindedly, it may indeed sting if it is a female bee. Male bees lack stingers.

Sweat bees come in a variety of sizes and colors, from miniscule brassy Lasioglossum species to brilliant metallic Agapostemon species (and related genera). Members of the genus Halictus are medium-sized and brown or blackish with white bands across the abdomen. Nearly all species nest in the soil, each female excavating her own burrow.

Compounding the problem of recognizing the different insects that seek out your sweat is the fact that many flies in the family Syrphidae are wrongly called "sweat bees" in casual and regional language. Syrphid flies are more properly called "flower flies" here in the U.S. and Canada, and "hover flies" in Europe.

Like bees, they can be important pollinators of flowers, but it is in their youth that they are most beneficial. The larvae of many flower flies prey on aphids, which are major crop and garden pests. Thus, the more syrphid flies, the better, even if they do want to drink your perspiration.

Plenty of other flies, mostly blow flies (family Calliphoridae), and flesh flies (family Sarcophagidae), will land on us, too. Even some tachinid flies (Tachinidae) will wander around on bare hands and arms. They may not all be there for moisture or salts.

Some of these flies may be males that are simply using us as convenient perches from which to defend their territory. They will periodically fly off to chase away competing males, or pursue passing females.

Some butterflies are well-known for requiring certain minerals to complete their life cycle. Usually, male butterflies congregate around mud puddles, puddles of urine or piles of scat left by mammals, or even rotting carcasses, where they obtain nutrients that they will pass to females during mating.

Males with a higher mineral content are more desirable to females, though how this is determined remains something of a mystery. She puts the transferred chemicals to good use in producing her eggs.

Occasionally, some butterflies will use us as substitutes for their usual mineral resources. I once had a Hackberry Emperor butterfly land on my toe while I was sunbathing in a park in Cincinnati. I had another land right on my sunglasses in a different location in Ohio, but he viewed me as a convenient perch from which to defend his territory.

Most research into the attractiveness of human sweat to insects has been directed at blood-feeding insects such as mosquitoes and other biting flies. Consequently, there is relatively little known, and much assumed, about the fascination non-biting "bugs" have with our skin pore excretions. One thing scientists can agree on? Don't sweat the sweat bees.

Source: Gibb, Timothy. 2015. "Do Not Confuse Hover Flies with Sweat Bees," Purdue Plant & Pest Diagnostic Laboratory, Purdue Extension, Purdue University.