Tag Archives: reproduction

Springtime with awesome, beautiful and awe-inspiring insects

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This spring of 2021 has offered some delightful chances to see interesting insect species, some of which I’ve noticed before and some that were new or gave me my first opportunity to observe them up close. While not many people aside from entomologists pay much attention to the “creepy crawlies,” they are certainly well worth watching in my view. Including insects in my nature observations greatly enhances my experience of appreciating the natural world.

male giant ichneumon wasp P5068000© Maria de Bruyn res (4)

ichneumon wasp P5067996© Maria de Bruyn res (2)

female giant ichneumon wasp P5068007 © Maria de Bruyn res (2)The month of May brought me two especially awe-inspiring events. The first was seeing long-tailed giant ichneumon wasps (Megarhyssa macrurus) preparing for reproduction on a nature trail in Chatham County. It was easy to distinguish the females (right) from the males (above) because they had very long ovipositors (a tubular organ through which a female insect lays stored eggs). In the species I saw, the ovipositor can be 4 inches long!’

female giant ichneumon wasp P5068028© Maria de Bruyn res (2)

There were several male and three female wasps flying about. None of them showed the slightest interest in the large human looming overhead. Even if they had, I needn’t have worried since these wasps don’t sting people. The females were busy pressing their antennae against a disintegrating hardwood log’s bark, aiming to detect vibrations inside.

ichneumon wasp P5068180© Maria de Bruyn res (2)

The mothers-to-be were “listening” for the best spots to lay their eggs by identifying where the larvae of the pigeon tremex horntail wasp (Tremex columba) were buried. Why you ask? The mother ichneumon paralyzes a horntail larva before laying an egg next to it. When her own offspring emerge from the eggs, they will eat those unfortunate horntail larvae while they prepare to overwinter until they emerge as full-grown ichneumon wasps in the spring.

ichneumon wasp P5068058 © Maria de Bruyn res (2)

 

The giant ichneumon’s ovipositor has three components. In the middle is the ovipositor proper, a filament with two interlocking parts that slide against one another; it is tipped with a cutting edge that can drill through wood. Some researchers have data indicating that the cutting edge may contain some ionized zinc or manganese.

ichneumon wasp P5068164© Maria de Bruyn res (2)

Two other thin filaments called valvulae sheath the central structure and their function is to protect the egg-laying organ. During egg-laying, they arc away from the ovipositor.

ichneumon wasp P5068171© Maria de Bruyn res (2)

While I watched one female wasp in particular, she sometimes had part of her ovipositor coiled up in a transparent expandable pouch at the end of her abdomen.

ichneumon wasp IMG_2003© Maria de Bruyn res (2) ichneumon wasp IMG_2002 © Maria de Bruyn res (2)

She would push out the ovipositor and appeared to smooth it out with her legs. The literature I read about the wasps did not explain this movement, but I thought she might be pushing eggs down the tube. Watch the video to see what you think! 

When she finished this smoothing movement and had found the right spots for her offspring, the protective lining filaments separated from the ovipositor itself and she inserted it into the log. It was a fascinating process to witness.

 

female giant ichneumon wasp P5068170 © Maria de Bruyn res (2)

female giant ichneumon wasp P5068109 (© Maria de Bruyn res (2)

Although ichneumon wasps are parasitic, various species are beneficial insects since their larvae feed on insects that harm food crops such as boll weevils, codling moths and asparagus beetles. The adults usually only live about 27 days and may only drink during that time. Their adult goal is to find a mate and then reproduce.

ichneumon wasp P5068014 © Maria de Bruyn res (2)

Another way in which the ichneumon wasps have contributed to human society is by serving as an example for the medical community. The STING Project at the Imperial College in London is investigating options for Minimally Invasive Surgery (MIS) to diagnose and treat various medical pathologies. The research team is now developing a flexible steerable probe that was inspired by the ichneumon wasp’s ovipositor!

cecropia moth IMG_0019 © Maria de Bruyn (2)My other exciting insect event involved a moth. Last fall, a cecropia moth (Hyalophora cecropia) positioned its cocoon on the door jamb of the women’s restroom at Cane Creek Reservoir. The reservoir’s manager feared that it would be damaged there and asked if I would be willing to care for it over the winter. I took the cocoon home and kept it safe during the fall, winter and much of this spring.

Cecropia moth larvae (caterpillars) are often found on maple, cherry and birch trees. Why this one chose a building as an overwintering site is a bit of a mystery. Since the pupa was going to be dormant all winter, I placed it upright in a large plastic container with a grate over the top and kept it on my screened-in porch.

cecropia moth IMG_0020© Maria de Bruyn (2)Periodically, I would check on it and it seemed to be ok. This was important as these moths are “univoltine” — they only have one generation of offspring per year. Out in nature, the caterpillars may fall victim to parasitic wasps and flies that lay their eggs on them. So it was fortunate that we were able to “rescue” this cocoon.

One evening at the end of May, I stopped working on my porch to go inside to watch the news. When I came back after about 20 minutes, I spotted a brilliant large moth on the screen. My youngest cat spotted it at the same time, so I shooed her inside. The cocoon scarcely had a hole in it; I really wish I’d seen how the huge moth got out.

cecropia moth IMG_0006© Maria de Bruyn (2) res

cecropia moth IMG_0003© Maria de Bruyn 2 res

The cecropia moth is North America’s largest moth with a wingspan up to 7 inches. The males and females look similar but the males like this one have larger, more feathery antennae.

cecropia moth IMG_0012© Maria de Bruyn (2) res

Female moths emit pheromones that the males can detect from up to a mile away. After mating, the female lays up to 100 eggs. Both sexes die after about two weeks as they lack functioning mouths and digestive systems and don’t eat.

cecropia moth IMG_0014 © Maria de Bruyn (2) res

 

The moth’s short adult lifespan must have made this guy anxious to get underway. Or seeing my cat and I hastened his development. One website reported that it takes the moth a few hours to dry before they can open their wings and fly.

cecropia moth IMG_0011© Maria de Bruyn (2) res

 

However, very soon (perhaps 10 minutes) after I removed him from my porch and took him outside (never touching him with my hands), he began vibrating his wings. In less than a minute, he launched himself upwards and flew towards the top of the nearby tall pine trees, setting off on his quest for a mate.

cecropia moth IMG_0016© Maria de Bruyn (2a) res

I suppose it is possible that the moth had emerged earlier and had crawled away to hide but that seemed unlikely. In any event, he looked like he could fly just fine, and I sincerely hope that he found a mate and that they were able to collaborate in ensuring a new generation of this stunningly beautiful species! And I was grateful for having agreed to overwinter the cocoon as it enabled me to contribute to the propagation of this wonderful moth. In any event, I was enthralled to see what a gorgeous creature he was. These moths are generally nocturnal so seeing him was a treat!

cecropia moth IMG_0017 © Maria de Bruyn (2) res

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Hopping into springtime

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I’ve been planning new blogs for quite some time; then I keep taking new photos that will fit into them and the blog writing gets delayed. But two days ago, I saw such a cool natural event that I resolved to produce a blog quickly and here it is!

One welcome feature of springtime is that many insects emerge from their over-wintering spots. Some are bugs we dislike (mosquitoes, ticks and chiggers), but others are fascinating and wonderful members of our natural systems. Pollinators like this spicebush swallowtail (Papilio troilus) keep our gorgeous plants and important food crops going and many bugs provide other wildlife with meals.

On my trip to Costa Rica last year, our guide not only pointed out birds but also some mammals and insects. He had developed an interest in treehoppers, a group of insects with about 3200 species worldwide that specialize in eating plant sap. He was unable to find any to show me, but I resolved to keep an eye open for them when I returned home. I had forgotten that I had seen my first one the year before, a pretty green Ceresini species.

As I stared at plants during nature walks, I was lucky and managed to find my first treehoppers when I was actually looking for them. These were of a dark-colored species (Acutalis tartarea) that favors the sap of black locust trees, sunflowers, goldenrod and ragweeds.

The treehoppers, which are related to leafhoppers and cicadas, are popular with some entomologists because many species have elaborate “helmets” at the top of their heads. I got to see my first example of this type on my recent walk when I happened to find a young oak tree with numerous nymphs and recently eclosed (emerged) adult oak treehoppers (Platycostis vittata).

The mother treehopper is known for staying close to the nymphs to protect them against wasps and other predators.

The hoppers get plant sap by piercing plant stems with their beaks. The nymphs have extensible anal ducts that deposit the sap away from their bodies. This is important because the concentrated excess sap, called honeydew, can get moldy.

 

                              

The honeydew attracts ants, which like the sugar-rich liquid, so the hoppers and ants have a mutually beneficial relationship.

Just how the helmet develops into an unusual shape has been a source of investigation. One team of entomologists theorized that the helmet was formed by body parts that were actually modified wings. Another researcher countered that this was impossible and that the helmet was an unusual pronotum — the foremost dorsal section of the thorax. More recently, a third group of evolutionary biologists postulated that the helmet is indeed a section of pronotum but one that developed with the aid of genes that code for wings.

In various species, the pronotum has developed into a quite unusual and oddly shaped appendage; examples can be seen in this article. When the helmet resembles a plant thorn, it is thought to aid in camouflage.

When I discovered the group of oak treehoppers, one was just in the process of emerging from its nymph form. A friend who saw the photo remarked that it reminded her of the film Alien but this process was slow and deliberate and not a heart-thumping explosive emergence as shown in the movie.

As you can see, the oak treehopper is quite a beautiful insect with its pristine white body decorated with pink/red stripes and hints of yellow. They made me think of mints and Candy Stripers (a sign of our times when almost anything makes me think of health and health-related concerns. For younger readers: young female volunteers who work under nurses’ supervision in hospitals used to wear pink and white striped smocks and thus got the name Candy Striper).

Not all the adults had the horned pronotum; some had rounded heads.

This close-up of a hopper’s face could evoke all kinds of thoughts. I thought it looked as if it had a pig’s snout. Another friend thought it looked like a grumpy old man. What do you think when you see this visage?

Or about this one, with its head upside down? (It looks a bit more “innocent”, don’t you think?)

In any event, I found these insects just adorable and I felt very privileged to have had the chance to see them emerge into adulthood. It turns out that in this species, older individuals may change color, turning a dull brown or green color. Some mottled forms may be blue with yellowish spots. It would be interesting to see those forms as well one day – or perhaps one of the other treehoppers with a different fabulous helmet!I hope you, too, are able to get out in nature during these social distancing times so that you can connect with the wonderful wildlife around us!

Summer hummers – entertainment for free: part 1

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When a hummingbird other than a ruby-throated hummingbird (Archilochus colubris) is seen in the Triangle area of North Carolina, it is listed as a rare bird on the Cornell Lab of Ornithology listserv. One year, I did have a chance to see a buff-bellied hummer visiting in a nearby town though; another year a rufous hummer frequented my own feeders in the winter. Mostly, however, it is the ruby-throats who take up residence at my address, which is just fine as these feisty tiny birds provide loads of entertainment.

 

During a trip to Quebec earlier this year, we also saw ruby-throated hummingbirds there – early arrivals during the spring migration.

 

A few years ago, one of my blogs focused on their preening and cleaning, so this time I’ll mostly feature some of my favorite photos of them taken this summer in various places. (When looking through the shots, I had a LOT I liked, so this is now going to be a 2-part blog!)

At Sandy Creek Park in Durham, one female hummer had made a coral honeysuckle (Lonicera sempervirens) one of her preferred dining spots.

 

 

A butterfly garden featuring blue-black sage (Salvia guaranitica) and bee balm (Monarda) also attracted her and some other hummers.

 

One female found the bee balm to be a good place to rest, understandable since these bundles of energy have a high metabolic rate. Their hearts beat up 1260 times per minute and they take about 250 breaths per minute even when they are resting! Taking a few sips while remaining perched has to be a welcome luxury.

 

 

 

 

The hummers’ main wing bone, the humerus, is adapted to hovering flight and they have very large deltoid pectoral muscles relative to their size.

 

 

Male birds produce sperm that flows through the vas deferens (sperm duct) to the cloaca. When they mate with a female, they transfer sperm by touching the tip of their cloaca to that of the female; they do not have a penis. Females only have a functional left ovary; the right one atrophies early in her development, which allows her to avoid the extra weight of a second ovary and makes her lighter for long migratory flights.

One big treat for me this year was finding two ruby-throated hummingbird females tending a nest, the first time I had been able to spot this.

 

Later, I was able to take a quick photo of one female collecting cattail fluff with which to line her nest.

Even when several ruby-throats are frequenting an area, the (temporary) coloring of their feathers can help distinguish them. This young male had a few olive-green dots under his eye and a bit of white on the crown of his head.

 

A somewhat more mature male has a little white patch behind his red gorget.

 

They are all little beauties! Second part of this blog is coming up and then on to Costa Rica!

Spring is in the air…. Uh, I mean water!

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It was the sound that first attracted my attention. Initially, I thought that it sounded like a flock of birds, but as I approached a pond, I realized that was not the case. The almost chirruping sound didn’t fit with any frogs I had heard before. As I scanned the scene before, my roving vision finally alit on a small section of brownish water dappled with green algae and stalks of dead reeds – there were moving bumps there. When I came closer, I finally realized that it was a mass of writhing and continually moving toads, engaged in what resembled a bit of a battle. It was actually what could be called a mating contest. (Click on a photo to see it larger; then arrow back to return to blog.)

The sound made by the male Eastern American toad (Anaxyrus americanus americanus) when he is ready to breed has been likened to an old-fashioned ringing telephone. It can last from 6 to 30 seconds and when multiple toads are calling at the same time, they create a very loud and penetrating “concert”. It doesn’t sound like a phone to me; you can judge by listening to the video.

I only saw a couple of the toads with inflated throat sacs. The sound was very loud, however, and the water was roiling with moving heads topped by periscope eyes, warty bodies and thrashing legs.

Before examining how the toads were going about their reproductive endeavor, a little biology lesson. Toads are a sub-group of frogs; while most frogs have moist skin, toads generally have drier and wartier skins. They vary greatly in color, including shades of yellow, brown, black and red, and may be speckled or have solid hues. The skin color can also change in response to stress, temperature, humidity and habitat.

 

American toads have two glands at the top of their head behind the eye crest. These are parotid glands that produce a neurotoxin, bufotoxin, which can sicken and even kill a predator. The milky substance can produce skin irritation in human beings and can be dangerous to smaller mammals (like dogs).

 

 

Like birds, toads have nictitating membranes, transparent eyelids that help protect the eye. They sometimes raise the nictitating membrane half-way so that they retain sharper vision.

 

 

Toads actually spend a lot of their lives on dry land, eating insects as well as worms, slugs and other small invertebrates. A particularly fascinating fact is that they use their eyeballs to help swallow food – when they ingest their prey, the eyeballs sink down into their mouth and help push the food down their throats!!!

At times, they created little whirlpools as they bumped up against one another or tried to mount a neighbor.

 

 

Sometimes, a large female with a smaller male atop her would rest quietly under water, apparently trying to avoid notice. This strategy did not always work, however, and sometimes one or more other males would try to join the pair already in amplexus (i.e., when the male grasps the female with his front legs and fertilizes the eggs as she releases them from her body)..

The female toad ejects her eggs in two strings, which are immediately fertilized by a nearby male spurting out a stream of sperm. (Frogs lay their eggs in clusters.) Tadpoles will emerge from the eggs within 2–14 days and reach adulthood within 50–65 days. They become sexually mature at 2-3 years.

In one case, I developed a real sympathy for a particularly large female. She had a small male astride her who resembled her in coloring and they looked to be peacefully joined. Then another male spotted them and he launched a sneak attack, trying to usurp the position of her already-present suitor. The first male clung on tightly.

No. 1 pushed No. 2 away with a hind leg again and again.

In the meantime, a great blue heron (Ardea herodius) who had been feeding on the other side of the pond, made its way over to the site of toad frenzy. S/he had been eating small fish and amphibians.

I thought the heron would plunge into the midst of the numerous toads for an easy meal, but instead the bird looked around and then skirted the group, veering away to the shoreline. Perhaps some instinct made the heron avoid the group during a reproductive event? Or s/he was put off by the vigorous activity of the potential prey?

A second rival toad then joined the first, who was still trying to get the original mating male out of the way. Eventually, a third, fourth and yet another male joined the group and the poor female was weighted down by 5 – FIVE! – male toads all vying for the prime spot on her back. Often her head was pushed down under water.

The first male clung on with great determination, often being pushed down under water as well as the other males piled on. He was NOT going to give up.

Ms Toad did not like this state of affairs. She laboriously began moving from a deeper spot in the pond to the pond’s edge. This was a slow process, made difficult by the clinging crowd who must have weighed a good deal as a group.

I thought she might be trying to get to more shallow water so the toad “knot” would not keep her submerged. Toads can breathe under water like frogs because they can absorb oxygen through their skin. They do have lungs, however, and if these fill with water, they can drown. A fellow Facebook nature lover told me that she had seen expired female toads with males still clinging to them. A toad knot can therefore unfortunately result in maternal mortality – the demise of a mother giving birth (to several thousand eggs; most of the tadpoles do not survive).

I soon left the scene after Ms Toad had reached the side of the pond and could keep her head above water. It was noticeable that her throat pouch was inflating and deflating – perhaps she was breathing deeply to compensate for lack of oxygen when she had to suffer a submerged head due to the over-amorous males.

 

Inhale!                                                                  Exhale!

I know I am anthropomorphizing, but I do believe that she likely felt the amphibian equivalent of relief and was looking forward to the end of that day!

When those loving instincts leave you dangling

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This was not a planned blog, but I recently observed something that simultaneously intrigued, amazed and astounded me, so I wanted to share it with those of you who may not have witnessed this either.

Like many gardens in my neighborhood, my yard has its fair share of leopard slugs (Limax maximus), but they don’t bother me as they do some other people who complain about them eating their vegetables. Until recently, I never thought about the slugs much and certainly didn’t wonder about their life cycle. Then my friend Mary posted a lovely photo of two intertwined leopard slugs mating and my interest and curiosity were piqued.

A few days later, a fellow nature lover, Ace, reported that he had a cool photo to show me – and there on his iPhone was a photo of mating leopard slugs. It turns out that their anatomy makes for a somewhat bizarre spectacle – at least to a human being if not a fellow slug. Now I really wanted to see this phenomenon, too, and I followed Ace’s recommendation, going out into my yard at night with a flashlight to see if I could find some amorous mollusks. Lo and behold – as I rounded the corner of my house, there were three pairs of large slugs getting ready to reproduce! They were leaving glistening slime trails on the brick wall as they slowly got into position.

The slime that the slugs exude has multiple purposes – they can leave a trail behind them as a signpost to the way home, they can numb the mouth of a potential predator with the mucus as a means of defense, and they can broadcast their interest in some reproductive behavior by emitting pheromones to attract a potential mate.

They don’t actually need to mate to reproduce – each slug is a hermaphrodite and can fertilize its own eggs with no need of outside assistance. Slugs have an organ called a spermoviduct (SO), which has two parts – one for the sperm (vas deferens, VD) and one for the ova (oviduct, OV), as seen as this drawing from the Wikipedia page.

Some slugs apparently like reproductive acrobatics, however, and seek out a partner. The mating begins with a pair of slugs following one another around and nudging and licking one another. (A couple photos look browner – I took those with a flash but most were taken with one hand holding a small camera and the other shining a flashlight near the slugs.)

 

They then begin to curl up together and suspend themselves from a long mucus rope, which is somewhat stronger than the slime that they usually exude. They form a kind of writhing ball as they intertwine their elongated bodies (see this video for an example).

Next comes the awesomely weird part – out of a gonopore on the right side of their heads (the elongated tentacles are for vision) come their translucent mating organs (penises)! This video, which is shown in a horizontal position, lets you see how this happens.

Wouldn’t this interesting anatomy and reproductive behavior make an interesting plotline for an SF novel about a genderless society?

 

      

Because the slugs are hanging upside down, gravity helps pull down their reproductive organs, which are pumped full of body fluids until they are as long as the slugs’ entire bodies! Their penises are everted (turned inside out) and the two mollusks intertwine these just like their bodies. They take a while to exchange spermatophores as the penises twirl, intertwine, elongate and pull back to look a bit like a chandelier.

  

When the creatures have been joined at the neck for some time, they begin to slowly withdraw their reproductive organs, which are now carrying genes from another parent.

              

After they separate, one of the pair usually consumes the mucus rope from which they dangled in love as it carries extra nutrients which they can use after their vigorous efforts.

          

 

 

Each slug may spend some time examining its gonopore (above) – and perhaps they are helping push back in the penis when they do this, too. After watching the process for two pairs of slugs, I decided to give the third pair some privacy during their mating tryst. On the wall beneath my screened porch, I discovered another slug with a mucus rope dangling from its tail – leaving me with a little mystery as to why this might have happened. A partner slug was not in evidence except for a much smaller slug – perhaps the big one tried to mate but the younger one was not ready. These mollusks with a life span of 2.5-3 years don’t become sexually mature until they are 2 years old.

    

I do know that at least three and perhaps six slugs will each be laying up to 200 eggs somewhere in the yard. And when I see them in the future, I will undoubtedly always be picturing them in my head doing their dangling dance with intertwined translucent blue tubes that will help promote their future generations. My discovery of their life cycle has also reinforced my support for scientist Hope Jahren’s (Lab Girl) observation: “…being able to derive happiness from discovery is a recipe for a beautiful life.”