Tag Archives: Insects

How do small insects not get hurt by raindrops?

It’s easy to intuitively think of raindrops hitting small organisms as being equivalent to cinder blocks falling from the sky and hitting us, but that’s not how it plays out.

Raindrops are not moving very fast, nor are they heavy. For a raindrop to be considered a raindrop it has to be between roughly .5mm – 6mm (about the size of a fly at the largest).  A big raindrop has a terminal velocity of about 10 m/s (20 mph), with smaller drops down closer to 0.9 m/s (2 mph).  That’s basically to say that there isn’t much energy in any given raindrop to do a lot of damage with.

Another part is that smaller creatures are quite strong and tough as a result of the Square-cube Law. This is why an ant or a spider is proportionally so strong and an element of this is why a mouse generally won’t fall fast enough to get seriously injured whereas a horse or an elephant will splash from a long fall. Also why a raindrop falling on a shrew or a butterfly isn’t the equivalent of a cinder-block falling on a human.

Raindrops can certainly hinder small organisms, but that tends to be more an issue of surface tension, heat loss, splashing and water flow, and things like that rather than the actual impact of the water droplet.

For many flying organisms fog (and, to a certain degree, drizzle) is actually  much more difficult thing to deal with as the tiny water droplets are suspended in the air and they accumulate on the surface of the flying organism, adding a lot of weight. This is why you usually don’t get mosquitoes buzzing about when it’s foggy.

Why do bees have stingers if using it will kill them?

Bees have a social order very different than ours. Don’t think of a bee colony as a bunch of individuals working togehter, like a city. Instead, think of a colony as a single organism made up of many small parts.

A bee will sting to defend its colony and queen, and it does not care if it dies, since it will never personally reproduce. Its existence is based on ensuring the survival of the hive, not of itself.

Because they never reproduce, there was no reason for a stinger that didn’t kill them to be developed. In fact because it benefits the colony (which, again, more like one thing than several things) by protecting the queen, the ability for the non-reproducing ones to deal as much damage as possible would be beneficial to the colony’s survival.

How do predators eat poisonous spiders and not die?

Poisonous and venomous are different things. Poisonous things may kill you if you eat them, and venomous things may kill you if they bite you.

To be specific, these spiders are venomous which means the toxin is intended to be injected into the tissues of the unlucky victim.

In some cases, venom does not achieve the same impact if ingested. They may be diluted in the stomach, less able to penetrate to the tissues where they can do harm, and the hostile environment may even break down the critical substances that give the venom its potency.

Why don’t ​fireflies get hot when they glow? Why can’t we make anything as efficient?

Bioluminescence is produced by chemical reactions involving molecules called luciferins. These chemicals are able to produce light very efficiently without a lot of waste heat.
As for making them, well, we can. The reason we don’t use chemicals for lighting is because, while efficient, they aren’t very bright. Try lighting a room with a bucketful of fireflies and see how much illumination they’ll give you. Enough to see, but probably not enough to read by.
Another issue is that bioluminescence requires a constant feed of new chemicals to power it. You need something producing new luciferins, as well as oxygen to make it glow. Like a fire, oxygen will be consumed in the reaction and must be replenished, so you can’t keep it isolated in a tube. Less convenient than electric lamps.
But for situations that don’t require much light, scientists are already looking into it – check out this bacteria-powered lamp (https://www.wired.com/2015/01/lamp-whose-light-comes-bioluminescent-bacteria/)! It has it faults – it isn’t very bright, the bacteria need to be fed, and it needs to be in motion to keep the oxygen flowing. But still cool stuff.
It also turns out that luminescent genes are one of the easier things to splice into basically anything. Scientists have made glowing plants, fruit flies, shrimp, mice, rabbits, and even cats. I’ve heard of plans to use genetically engineered glowing trees instead of street lamps in some cities, so that’s something to look forward to.

How do flies constantly fly into hard objects at high speeds yet don’t get hurt?

Imagine you had a ping pong ball, and you filled it with cool whip. Now shrink that whole thing down to the size of a fly. Now imagine you threw that tiny little shell full of goop at the wall. Even if you threw it as hard as you could, it’s still so tiny and so tough and bouncy on the outside that it will just bounce off.
Flies have an exoskeleton that’s incredibly tough and hard in some spots, and just flexible enough to be springy and bouncy in others. Just like that ping pong ball, they have got a shell that’s good at taking a bit of a hit and bouncing off instead of just squishing like a worm (which doesn’t have that tough shell).
The fact that they’re so small helps in a couple different ways as well. For one, we think they’re flying super fast, but it’s really just because they’re tiny. If you look at a massive airplane, it might be moving at 500 miles per hour but still looks like it’s just crawling along across the sky. Houseflies look fast, but they only go about 5 miles per hour. That means a baseball pitcher can throw a fastball 20 times as fast as a housefly flies.
Not only are they actually super slow (if you don’t let the size trick you), they also weigh almost nothing. Like, it would take about 200 flies to add up to the weight of a single ping pong ball.
So your ping pong ball full of cool whip is actually super tough, reaaally slow, and unbelievably lightweight, meaning that dumb little fly was designed to fly into the window several thousand times before it finds the opening. Evolution at work.

How do mosquitoes find people in dark?

Click to enlarge

Mosquitoes are among the most annoying pests for humans. It might be when you are enjoying a summer evening outside when you suddenly find yourself surrounded by mosquitoes buzzing about you. Despite your swatting, they persist and bite you, rewarding you with welts and stinging sensations. If it was only the pain, we could have at least tolerated. But mosquitoes are transmitters of several life-threatening diseases like malaria and dengue fever, which make them dangerous. Millions die from these diseases across the world every year.

Contrary to popular belief, mosquitoes don’t drink blood as meal. They feed off mainly plant nectar. Only female mosquitoes bite people, and they do that to get the protein needed to develop their fertile eggs. They have an acute ability to spot their targets and attack them.
Like many other insects, mosquitoes are also attracted to the smell of carbon dioxide. They have a group of nerve cells called cpA neurons which contains a receptor to detect carbon dioxide. These receptors also sense skin odor, according to experiments carried out by a group of scientists at University of California. The human body emits nearly 300 types of odors, most of which attract mosquitoes.
In another series of experiments conducted in the California Institute of Technology, the scientists found out that mosquitoes use a combination of different senses – visual, olfactory (relating to smell) and thermal – to determine their target. The researchers placed mosquitoes in a tunnel filled with carbon dioxide plumes which attracted the insects. They also found that in the presence of carbon dioxide, mosquitoes zeroed in on objects more, especially warm objects.
According the tests, the mosquitoes can detect the smell of carbon dioxide as far as 50 meters. They follow the smell and from 15 meters they begin to see the human. They have a keen sense of vision and can spot movement. However, they rely on visual cues only after using the olfactory senses which helps them in time management.
Upon reaching very close to the person – within a meter – they can sense the body heat and pick up the odors emitted by the body. They waste no time in attacking their target then. Once they have locked onto the target, it is hard to get rid of them short of killing.
Chemicals emitting odor unattractive to mosquitoes can be used to repel them. There are also chemicals that emits attractive smell which can be used to lure the insects into traps.
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Why do mosquitoes bite some people more than others?

Suppose you are enjoying an evening with friends outside. Suddenly you find yourself victim to mosquito bites while your friends seem to be spared by the insects. And you can’t figure out why. It is indeed a case for a fair number of people. Some people seem to attract the attention of mosquitoes almost like a magnet. In fact, around 20% of the people in the world fall under that high attracting category. While scientists have not been able to pinpoint the exact causes of this phenomenon, studies have emerged, coming up with various factors that might be playing major roles.
Sight and smell are regarded to play the seminal role in mosquitoes’ selection of their targets. As mentioned in another post, mosquitoes use their visual, olfactory and thermal senses to spot their target. The creatures are very visual and they can spot dark colors easily. People wearing dark clothes often find themselves surrounded by mosquitoes rather than those with lighter clothes. In a study, it was also found that there is a correlation between blood group and the mosquito attacks. Those with blood group O are more favored by the insects, about twice the number of those with type A blood.
Perhaps the most important thing that attracts mosquito is the carbon dioxide exhaled by us. They can detect the gas from as far as fifty meters. People who exhale large quantities of carbon dioxide are naturally prone to mosquito bites. Obese people often exhale strongly than others, emitting more carbon dioxide, and mosquitoes relish them. In addition, body temperature plays an important role as well, and it may cause mosquitoes flock to a person. For example, pregnant women are particularly vulnerable to mosquito attacks, due to their fatty frame as well as the additional body heat. People with more cholesterol on their skin also attract mosquitoes.
Mosquitoes are attracted to various other smells as well. No wonder why our bodies, which emit various odors, are so desirable to them. Certain types of acids produced in the body, such as uric acid, are known to attract mosquitoes because they heighten their sense of smell. Other chemicals that draw mosquitoes towards us include lactic acid, acetone and estradiol. Our body odors are the results of the work by more than 300 chemicals, and it is not easy to find out exactly which one is most responsible. Some have also come up with the view that it might not be about the attractive smell, but rather about the repelling ones. Those who are bitten less might be producing odor mosquitoes find unattractive, according to that view.
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How silk is made from cocoon?

Silk is one of the most favorite fabric materials in the world. It has been so for thousands of years. The soft and shiny material is almost a prized item in many places. Silk has been known for several millenniums. The earliest known specimen of silk fabric was discovered from China, which dates back to 3630 BC. China is also the largest producer of the material. The historical Silk Route says how much importance silk had in bygone eras.
Silk is essentially a natural protein fiber. It is made by several insect larvae to form cocoons. However, the industrial silk is produced from the worms of moth species Bombyx mori. An unfortunate side effect of this is that the pupae have to be killed to obtain the material. It takes the killing of about 3000 caterpillars to get a pound of silk.

Silk cocoon from silk worm (probably Bombyx mori)
The cultivation of silkworms is called sericulture. The eggs of moths are incubated for 10 days. They hatch to produce caterpillars which are fed on mulberry leaves for about five weeks. The caterpillars then begin to spin the cocoon. This time, they would weigh about 10,000 times heavier than they did at the time of hatching. While making cocoons, the caterpillars move in a certain pattern. They secrete a liquid protein named fibroin from two glands and force it out through openings in head called spinnerets. They are coated in a protective agent called sericin, which hardens with air contact. The caterpillar would produce about 1 mile of filament in three days.
The cocoons are then soaked in boiling water to kill the pupae and soften the sericin. The fibers are then unwound to form a continuous thread. This process is called reeling. Since a single strand is too thin for commercial use, a few (usually between 3 and 10) are twisted together to form a single silk thread. This is called reeled silk. There are different twisting methods, and each produces a distinct type of silk. The shining appearance of silk is from the triangular prism-like structure of the fiber. Owing to the structure, the incoming light refract at different angles, thereby producing different colors.
Since numerous pupae have to be killed to produce silk, many animal right movements have raised their voice against the industry. The scientific world is trying to come up with methods that don’t require killing of the worms, which may come to fruition soon.

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Is it true that dragonflies can fly up to 60 mph?

Dragonflies have been around for about 300 million years. There are a lot of myths and fables around these tiny insects. Some believe they are actually descendants of dragons although no substantial evidence is there to support it.
There are more than 5000 species of dragonflies around the world, distributed across all continents except Antarctica. Some characteristics are common to all species, like multifaceted eyes, long body and two pair of wings. They are very good fliers and one of the largest flying insects. However, they can fly only for a few weeks at the most as their lifetime is very short. They lay eggs in water bodies and spend a major part of their life in the larva stage. The duration of this stage can be up to three years in some species. After becoming an adult, they live for only a few weeks.
The wings of dragonflies can operate together or independently. It gives the dragonfly the ability to fly in six directions and in four different styles. Some species can fly for a long time continuously. The Globe Skimmer dragonfly migrates across the Indian Ocean for a distance of about 11,000 miles. The larger species of dragonflies are faster than the smaller ones. In general, their speed varies between 20 to 35 mph. However, there are several reports that dragonflies can reach up to 60 mph in flight. It was reported by famous entomologist Robert John Tillyard in the article The Biology of Dragonflies in 1917. He observed that a fly of the species Austrophlebia costalis reached a speed of 98 kph along a downward flight. However, there are no other reliable sources available to support this claim. Still the speed of 35 mph makes dragonflies among the fastest insects.
The eyes of dragonflies are a special feature of them. They have large spherical eyes, with nearly thirty thousand facets in each one. The insects such have a field of vision of almost 360°. The combination of the flying ability and sight makes it easy for dragonflies to catch the prey. They are among the best predators in animal kingdom. According to scientific studies, they catch 95% of the prey they target, making them more successful than lions and sharks.

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Do moths really eat clothes?

Sometime you open your wardrobe and find that moths have eaten a hole through your favorite shirt or any costume that matters. There would be no limit to the frustration and anger you would feel. Many people have had a similar experience with the tiny insects. But really do moths eat clothes? The answer would be no, technically of course. It is not the adult moths that eat clothes but their babies, the larvae; not that it would make you anymore happy when you discover your emaciated costumes. Even then, there are only a few species of moths that take interest in clothes in their childhood, belonging to the family of tineola. The Webbing Clothes moths (tineola bisselliella) are the most common cloth killers.
The adult moths actually do not eat, be it clothes or anything else. They simply don’t have the faculties to do so. The moths possess a mouth only in larval or caterpillar form. Once they mature, the primary thing on their to-do list is mating. After mating, the females lay some eggs and go on to die. It is the laying of eggs part that makes them enemies of people.
The female moths can lay a hundred to thousand eggs at a time and your cloth is as good a place as any for them to do it. They are particularly attracted to moist conditions. When the egg hatches into the larva stage, the problem begins. The moth larva’s diet primarily includes proteins, a huge amount of them. A good source for them is keratin, which is composed of many fibrous structural proteins. Keratin is found in every animal fiber and in the human hair and skin as well. So they will eat anything that contains an iota of animal fibers, such as wool, fur, cashmere, silk, cotton, linen, feathers, lint and others. They can even consume our hair. The larvae don’t eat plant-based fibers like cotton and synthetic fibers like polyester since they do not contain keratin. However, they are known to cut through them in search of their favorite food. They have mouth only in the larval or caterpillar stage, which starts about when they are two weeks old and lasts till it turns a month old. The food they eat becomes a part of the cocoon they create as well.
The best way to prevent the moths from destroying your clothes is dry cleaning them. The mothballs are not effective and only help to agitate humans. Don’t let a moth find a suitable place to lay eggs in your wardrobe.

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