Secrets of the sand trap (Antlions)

10/09/23 • 10 min

This week is a listener request for Antlions! We look into how sand traps are made and what unique tactics antlions use to keep their prey from getting away.

Patreon -> https://www.patreon.com/user?u=46499107

IG: https://www.instagram.com/insects4fun/

FB: https://www.facebook.com/profile.php?id=100085443614825

Email: [email protected]

Music from lofi girl with featured artists: HM Surf and S N U G,

Transcript:

Welcome to episode 59 of Insects for fun! The entomology podcast hosted by me is your not so local entomologist, and today we have a new listener request from a listener named Joseph out in Hungary! So without further ado let’s dig into it (animal crossing shovel noise)

Antlions are a group of insects in the order Neuroptera which are net winged insects like lacewings and mantidflies and we will definitely be getting to those ones at another time. But today is all about the antlion which are a group of really interesting insects in the family myrmeleontidae of which there are around 2,000! The name antlion appears to have come from the classical era which started in the 8th century before common era, as for why they got this name the most widely believed reason is simply that they prey upon ants like a lion, at least during their larval stage. The insects can be found throughout the world but prefer living in warmer climate areas, especially dry areas like dunes, sandy pine soil barrens like the beach towns in Cape Cod, barren parking lots, basically anywhere that’s got dry or sandy soil. This is not to say they can’t tolerate rain because they can, it’s just that a very rainy area doesn’t exactly pair well with the strategies many of these guys have, and if they are in a rainy place then they choose to make their tunnels underneath cover like fallen debris, trees or or man made structures.

Antlions like all lacewings go through complete metamorphosis, and the larvae are predatory unlike the adults, feeding on ants as well as other small insects, but unlike a lion they don’t chase down their prey. They instead wait for their food to come to them and then take advantage of the moment. Most actually build a funnel-like sand trap and lay in wait at the very bottom. You know the giant sand monster in Star Wars? The one that jabba the hutt would throw prisoners into for fun? I think its name is sarlacc, well that crazy thing is modeled after the larva of an Antlion. OR maybe you’re a star trek fan, in that case think of ceti eel which apparently made its debut in star trek 2 the wrath of khan.

The larvae burrow into the ground butt first and use their arms to fling sand and debri up and out as they form a funnel. Once the trap is made they sit and wait for ants and other insects to walk, slip or fall into their trap. They can tell something is there by feeling the vibrations in the sand using sensory hairs on their bodies which I talked about in a recent episode. These sensory hairs are pretty good and can detect movement of nearby insects that haven’t even entered the funnel trap. Once something has entered the den, the antlion larvae begin flicking sand at the target to create a small landslide, and they are very precise about this, and know exactly how much sand to flick to push their prey to the bottom. If you see videos of these online they absolutely look like sand dune monsters from a sci-fi film. But some species don’t go this far in trap creation, and prefer to stay in premade holes of trees or rocks waiting for something to walk by. Either way these insects are opportunistic feeders, and don’t go chasing down their food. To be honest I don’t think they could even if they tried based on how crazy their bodies are. Of course waiting for your food to come walking by isn’t exactly reliable, and there may be times when little to nothing comes by at all and it's for these reasons that the antlions have very slow metabolisms. They can actually go months without food which actually prolongs their lifespan. That being said, if a location really isn’t providing then the insects will move to a new location. Joseph mentions seeing this happen at the local playground he takes his son to. What’s really interesting and funny is that the larvae move backwards! They could go forward if they wanted, but it’s much easier for them to move this way because of how their body is built. In parts of the US people actually call them doodle bugs because the paths they make in soft soil look like little doodles or drawings made by someone dragging their finger around.

Antlions spend the most time as a larva and only pupate once they’ve reached maximum size. This will of course depend on the species but ...

This week is a listener request for Antlions! We look into how sand traps are made and what unique tactics antlions use to keep their prey from getting away.

Patreon -> https://www.patreon.com/user?u=46499107

IG: https://www.instagram.com/insects4fun/

FB: https://www.facebook.com/profile.php?id=100085443614825

Email: [email protected]

Music from lofi girl with featured artists: HM Surf and S N U G,

Transcript:

Antlions spend the most time as a larva and only pupate once they’ve reached maximum size. This will of course depend on the species but ...

Previous Episode

Natural born divers! (Predacious Diving Beetles)

This week we look at Predacious diving beetles which are some of the largest aquatic beetles in the world and uncover their methods for staying underwater, as well as what they're diving for.

Patreon -> https://www.patreon.com/user?u=46499107

IG: https://www.instagram.com/insects4fun/

FB: https://www.facebook.com/profile.php?id=100085443614825

Email: [email protected]

Music supported by Lofi Girl with featured artists: cxlt, HM Surf, sleepermane, and Lofi study music.

Transcript:

Welcome to episode 58 of insects for fun! The weekly podcast on all things entomology hosted by me Mitchel Logan. I actually just realized recently that it’s been over a year already since starting this podcast. I genuinely can’t believe it went by that fast, but here we are! And before we get into the topic I want to thank this month's patrons Caden, Kirsty, Tina and Todd as well as all the people choosing to rate and review this podcast!

If you’re a weekly listener and have not yet hit the star on spotify or dropped a review and rating on Apple it is one the best ways you can show your support for the show and helps the algorithm push it to more insect fans!

Okay, today we’re quite literally diving into a topic (badum chuck) sorry. But yeah let’s just jump into it! (splash)

There are quite a few different kinds of diving beetles, but today we will focus on just one family, and those would be the predaceous diving beetles in the family Dytiscidae. The family name comes from the greek word dytikos which means able to dive. With over 4000 species the diversity in this group is quite vast and they can be found in every part of the world, well, every place but one...

At any rate, these beetles all have a relatively similar shape being oval or football shaped with long legs built for pushing water. The legs are usually all crammed close together as well which is different from terrestrial beetles. Oftentime they have very fine hairs on their legs too, specifically the hind ones which make them appear like long brushes or feathers underwater. It’s not easy to see these when they’re out of the water though, and yes they do fly! (wow) I actually found a really nice diving beetle in a closely related family while black lighting with a friend the other night. The vlog is available for viewing at Patreon.com/insects for fun.

Predaceous diving beetles are also referred to as true diving beetles because they are indeed professionals when it comes to diving. Their body is built for it, and they can stay submerged underwater for hours at a time. It’s hard to say what their average time underwater is because each one is different. Some last 30 minutes, some last 3 hours, and apparently the longest recorded dive was 36 hours. I tried getting an exact species for this claim but was unable which makes me wonder what they actually meant by 36 hours... because the thing is these beetles store air under their elytra or outer shell, and a diving beetle can easily replenish this air by simply floating up to the surface and poking the back end of its body out. I did however find a research article stating that they can spend up to 24 hours fully submerged so who knows.

One really incredible evolutionary mechanism for these would be the ability to use this air bubble as a crude gill. The bubble itself can actually replenish some oxygen from the water in the same way fish gills filter the oxygen. If you’re wondering how a bubble can do that it comes down to the size, the larger an air bubble is the more oxygen it can naturally pull from the environment, and some diving beetles are nearly 1.5 inches long and 1inch wide which for our metric listeners would be 4cm by 2.5cm.

So we got these beetles that are natural born divers, but what are they diving for anyway and why do we call them predacious? Beetles in the family Dytiscidae are carnivores, and they hunt anything from frogs to fish and of course other insects. They’re also scavengers which feed on sick and or dead animals at the bottom of water beds. They really are quite handy to have around! Even the larvae are predaceous and are actually referred to as water tigers! These larvae are not your traditional larvae at all and kind of look like a mix between the nymphs of other insects and ladybug larvae. They spend their days preying upon anything from tiny fish and tadpoles to other insect larvae including other water tigers. They are top predators within their niche and are known to be quite beneficial at keeping mosquito populations down! What I think is really cool about them is that they can catch prey passively by floating still near the surface and then gra...

Next Episode

The North American moon moth! (Actias Luna)

This week we look at a very special giant silkmoth that comes from North America (Luna moths). The species is incredibly iconic, and there are many different meanings for it across various cultures. The best part is you can also raise them relatively easily as a pet!

Patreon -> https://www.patreon.com/user?u=46499107

IG: https://www.instagram.com/insects4fun/

FB: https://www.facebook.com/profile.php?id=100085443614825

Email: [email protected]

Music provided by Lofi Girl with featured artist: Brillion.

Transcription:

Welcome back to episode 60 of Insects for fun! I wonder what we should do for episode 100... I’ve also been thinking of adding other arthropods into the mix. What do y'all think? Let me know in the comments section either on IG, FB or in your podcast player. Also when this episode is released I’ll be on a flight back to Japan from the states, so I’m currently writing this weeks in advance. Recently we have had some moon viewing stuff going on in Japan, and I figure what better time than to talk about one of my favorite moths, the Luna moth.

Lunas are in the giant silkmoth family Saturniidae and the genus is Actias. There are actually quite a few species of moon moths in this genus, but not all of them are green like the well known luna. Fortunately in Japan the two different species we have are quite similar to the luna, and I’ll be trying my hand at raising one of them next summer.

Actias luna have large and gorgeous pastel green wings with big fluffy white bodies, and one eye mark per wing. The wingspan can reach 5 inches across and also have long tails which only further adds to their celestial appearance. The name Luna is actually in reference to the roman moon goddess Luna, but this was not always their name! The initial name for these was actually plumata caudata which translates to feather tail, and these moths were the first American giant silk moths to be documented in literature. The name was later changed by Linnaeus in 1758. There are actually quite a few giant silk moths with mythological names like Polyphemus, Prometheus and Atlas for example, but the majority of them are brown or a variation of it. The Luna moth can only be found in North America, and not even the entire continent either. These moths chose a side and thankfully for me it was the east! You can find lunas from Canada down to Florida but they stay east of the great plains, and in Canada they’re found from southern Saskatchewan to Nova Scotia. I’ll never forget the first time I saw one, and thankfully finding them doesn’t seem to be all that difficult if you know where to go.

Luna moths are quite partial to forested areas but what kind of plants they eat is dependent on their geographical location. For example the caterpillars we have in Vermont love eating Birch, but I’ve also been successful at raising them on black walnut as well. Other common hosts include Butternut, Sumac, Sweetgum in the south, Alder, Beech, wild cherry and even persimmon. The time of year to find adult moths also varies heavily by location as well and this is because warmer weather allows them to have multiple breeding seasons unlike the northern populations. In Northern Vermont we have one generation a year and our Lunas start coming out of their cocoons in late May. In the south it’s not uncommon to have 2 or three generations in a year depending on the state. Massachusetts for example is right under VT but can have a partial 2nd generation.

The caterpillars are also an incredible green, and they can get pretty big. The 5th and last molt reaches a size up to 3inches or 7.5 cm and has red dots sprinkled over its back. What’s unique to these compared to other giant silkmoths is that the entire caterpillar actually turns red right before it begins making a cocoon. At least that’s been my experience but I’ve also read that some of them turn brown or orange as well. But it's not the color or the ability to change colors that makes Luna moths interesting or the moths in the genus Actias. It’s actually the tails on their wings that have attracted a lot of attention. Some species in the genus actias have tails on their wings that reach 12cm in length, and that’s just the tail section! I can’t tell you these are the only moths with long tails on their wings but I can definitely say they are one of a handful, and the reason they have these tails is to protect them from bat attacks! Bat’s rely on echolocation to find their prey, and it's one of the reasons why they fly in close quarters to people fishing in the evening. The sounds bouncing off the water from lures being whipped draws them in which can be intimidating I gotta say, ...