Litinsects

Litinsects #10: What is a bug? Raise your hand 🤚 if you’ve ever used the words “insect” and “bug” interchangeably? I hate to break it to you, but you probably haven’t been using the word bug correctly. You see, bugs are a kind of insect but NOT ALL INSECTS ARE BUGS! TRUE BUGS make up an order called HEMIPTERA. They can vary widely in their appearance but all share one basic feature: mouthparts modified into a stylet-like ROSTRUM, as you can see on the specimens pictured. Don’t worry, this isn’t some mutant species of legless bug, I just removed the legs so the entire rostrum is easily visible. Now let’s learn some more about TRUE BUGS: Examples of Hemiptera include: aphids, stink bugs, cicadas, bed bugs, scale insects, planthoppers, shield bugs, and assassin bugs Hemipterans use their piercing sucking mouthparts to feed on a variety of fluids. Most are plant-eaters, using their rostrum to pierce leaf cells and extract plant sap. Some are predatory w...

© Christopher Marley Litinsects #9: Beetle Biodiversity Take a minute and think about all the different animal species that science has named... from sponges and snails, to earthworms and scorpions, to sharks and birds and humans. What if I told you that a quarter of all the animals that we know of right now on this planet 🌍 ... are beetles?! I know it’s hard to imagine...all the people... living life in peace... oh wait, wrong kind of beetle! 😜 There are around 380,000 named beetle species at the moment. They make up about 40% of all insect species but scientists think there could be a MILLION more beetle species that haven’t been discovered yet! They are found in almost every type of habitat except polar regions and the open ocean and come in all shapes, colors, and sizes imaginable. Now for some fun beetle superlatives: The HERCULES BEETLE is the longest beetle and one of the largest flying insects in the world, measuring up to 17cm (7 in). It can lif...

Litinsects #8: Butterfly Wings Have you ever heard that you shouldn’t touch a butterfly’s wings or it will die? Well why is that...? Who remembers what I explained yesterday about Latin names? Butterflies and moths belong to the group LEPIDOPTERA, from the Greek words lepis for scale and pteron for wing. You probably guessed it already: butterfly wings are covered in SCALES! (Anyone starting to see a pattern with the names here? 😉 ) Butterfly scales are actually modified, flattened SETAE (aka hairs) that either partially or entirely cover the wings of most species. Some look like roof tiles, like on this here monarch, while some look more thread-like Scales protect and insulate the insect, but underneath the wing is actually transparent! Some species, like the GLASSWING BUTTERFLY, lack scales and have totally amazing see-through wings! Scales are responsible for the coloration of butterfly wings in one of two ways. First of all, scales contain...

Litinsects #7: Halteres Let’s talk about nomenclature for a second... Lots of species’ scientific names are composed of Greek words that somehow describe the group or a defining feature of the group. A bunch of insect groups include the ending –ptera because, you guessed it, most insects have wings! The scientific name of flies is DIPTERA, which should be relatively easy to decipher... it means TWO WINGS! But wait a minute, you may be saying to yourself, all winged insects have 4 wings right?! Yes they do, BUT o ne pair of wings can sometimes be modified into other structures. If you remember from beetles 🐞 , the forewing has been modified into elytra and they use only their hindwings to fly. Well in flies, the hindwings have been modified and they use only their forewings to fly. The second wing pair has been reduced to small structures called HALTERES. Halteres oscillate rapidly during flight, detecting rotations and perturbations. Flies use sensory info...

A general overview of arthropod body plans and phylogeny (relationships) of the four extant groups. <https://dev.biologists.org/content/129/5/1225/F1> Litinsects #6: What defines an insect? I realize I’ve been throwing around words like arthropod and insect but maybe not everyone knows how these groups are related. Today I'm going through some classification basics. First off, insects are ARTHROPODS, meaning they have paired JOINTED LIMBS. Arthropods include 5 main subgroups: (Future posts will go into each of the other arthropod groups in more detail...) (1) Trilobites, which are extinct (2) Chelicerates, which include spiders, scorpions, and mites (3) Myriapods, consisting of millipedes and centipedes (4) Crustaceans, including lobsters, crabs, and barnacles (5) Hexapods, the group to which insects belong Arthropods have a hard EXOSKELETON made of chitin that supports and protects the body. All arthropods grow by MOLTING, a process by which the...

Litinsects #5: How do grasshoppers hear? Can grasshoppers hear? Yes! As a matter of fact, any animal that uses acoustic signals to communicate must have organs to pick up these signals, otherwise what’s the point? Animals may use sound to detect predators, localize prey, and/or find mates, which is the case in grasshoppers as well. But their ears 👂 are very different than the ones sticking out from the side of your own head right now... 🦗 Grasshoppers and some other kinds of insects hear using a TYMPANUM (or tympanal organ) which is basically a structure like the human eardrum. Real quick, the basics: Sound is made by waves that cause the surrounding molecules (usually air but it could also be another medium) to vibrate. Hearing is the perception of sound through the detection of these vibrations. Thus, in order to hear, some sort of auditory organ must detect vibrations in the surrounding medium and change them to nerve impulses that can be sent to ...

Litinsects #4: Simple Eyes Yesterday I talked about compound eyes, the multi-faceted structures that most insects use to see the world 👀 But insects actually have another visual system as well, composed of simple eyes or OCELLI. Unlike compound eyes, ocelli are composed of only one structure which makes them comparatively “simple” although they are still very important. These are light-detecting organs consisting of a single lens with sensory cells. They can detect movement but don’t form complex images. “Ocellus” comes from the Latin word oculus, meaning eye. So these structures are literally “little eyes” Ocelli are located on the insect’s head, usually between or adjacent to the compound eyes. They are usually dome-shaped, somewhat shiny structures In most flying insects (such as flies, dragonflies, bees, etc.) there tend to be three ocelli in a triangle arrangement (see photo). Some terrestrial insects (like cockroaches) have only two ocelli ...

Litinsects #3: Compound Eyes I spy with my little eye. Eyes have evolved independently numerous times, which is why they vary so greatly in form and function depending on the organism (notice how I said organism and not specifically animal...? Well it depends on how eyes and sight are defined but animals are not the only life forms that can “see”).  Insects 🐝 and their close relatives the crustaceans have COMPOUND EYES, which are these multi-faceted eyes that you’ve probably seen in flies... So how do they work? Compound eyes are composed of units called OMMATIDIA, which are usually hexagonal in shape. A single ommatidium is like a mini eyeball: it contains photoreceptor cells, a lens, pigments, and an axon bundle that provides the animal’s brain with a small section of the picture that’s in front of it. The brain puts together the visual information from all ommatidia, forming just one image. So flies don’t actually see the world as a kaleido...

Litinsects #2: Beetle Elytra Beetles, like this ladybug here, come in all shapes and sizes but have one basic thing in common: hardened (sclerotized) forewings, named ELYTRA, which cover and protect their bodies. In flight, the elytra are lifted up and the hindwings are extended so, functionally, beetles actually only use one pair of wings to fly. Now for some FACTS about beetle wings... 🐞 The scientific name for beetles is COLEOPTERA, which comes from the Greek koleos, meaning sheath, and pteron, meaning wing Elytra are not “used in flight” per se but do have an effect on lift and drag. They also serve to TRAP MOISTURE and keep the hindwings from dehydrating Beetles’ hindwings are usually much longer than their elytra. At rest, they are FOLDED longitudinally (the long way) and then transversely (across) and tucked under the elytra (see second picture) Most insects fly with their legs tucked against their bodies to reduce drag but beetles fly...

Litinsects #1: Dragonfly Wings Ever wondered why dragonflies have this dark cell at the front of their wings? This is called a PTEROSTIGMA. This thickened cell is heavier than the rest of the wing, so scientists believe it helps the insects in gliding by reducing vibrations in the wing. Pterostigmata are found in all dragonflies and damselflies and a few other insect groups. And now for some FUN FACTS about dragonfly wings: Dragonflies are one of the FIRST groups of winged insects to evolve! The shape and vein patterns of dragonfly wings can be used in species identification Dragonflies can operate their fore and hind wings INDEPENDENTLY (which almost no other insects can do!) This gives them a level of control and agility that makes them amazing aerial hunters The globe skimmer dragonfly makes an annual multigenerational migration of 18,000 km (11,000 mi), the LONGEST of any insect Dragonflies and damselflies are easily distinguished by their...

All week I’ve been seeing videos and posts of the creative stuff people have been doing while social distancing, all the while thinking, what could I contribute to all the people sitting at home on social media all day?? Well this morning it hit me. I will do what I do best! And that is... drop some nerd knowledge on you all 🤓 Welcome to my social distancing ENTOMOLOGY COURSE!  Every day I will post an insect photo, most of which I’ve taken through my microscope, and explain about the insect group or the feature pictured. My hope is that you might learn something new about insects and maybe, just mayyyyybe, be a bit more fascinated and a bit less grossed out by the most diverse and arguably most successful group of animals to ever live... thanks for reading, stay tuned 🦋 🦟 🦗 🐞 🐜 🐛