Category Archives: Insects

Behavior and facts

Sunflower fields as critter-friendly habitats — part 2: bees and bugs

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Do you know why the common name in English for Helianthus is sunflower? The common name is the same in Dutch (zonnebloem), German (Sonnenblume) and several other languages. In French (tournesol) and Spanish (girasol), the common names refer to “turning to the sun”, an accurate description of how this plant behaves.

Sunflowers exhibit a phenomenon known as heliotropism — an inclination to turn East in the morning so that the developing buds are warmed by the sun. The plant heads track the sun during the day and, at night, they reorient themselves to face East again. So if you pay attention when you visit a sunflower field at different times of day, you’ll notice they face a different direction in the morning and afternoon.

It’s not only birds, butterflies — and people! — that enjoy sunflowers. When these flowers grow in abundance, plenty of varied insects come to enjoy them and I’ll share something about these “sun worshippers” with you.

Bees of varying sizes were feeding in the sunflower fields that I visited. The large carpenter bees (Xylocopa) were not difficult to spot with their smooth shiny abdomens.

The similar-sized, fuzzy-looking bumble bees (Bombus) were actively visiting one sunflower after another.

American bumble bees (Bombus pensylvanicus) were foraging on nearby hibiscus blooms.

At a different site in neighboring Durham county, where sunflowers bloom later, I saw bumble bees on partridge peas and other yellow flowers.

 

There, too, my attention was caught by a bee that looked quite different from others that I’d seen. It proved to be a leafcutter bee (Megachilid), which has large mouthparts that enables it to cut pieces of leaves, plant resins and soil to line its nest.

The leafcutter bees are interesting in their unique method of carrying pollen. Rather than collect pollen in baskets called corbicula on their hind legs, they gather the substance in a clump of abdominal hairs called a scopa or pollen brush.

Back at the sunflower fields, I observed one medium-sized cuckoo bee (Epeolini) eventually become covered with sunflower pollen. These bees do not have an anatomical structure for carrying collected pollen and the females, like avian cuckoos (or cowbirds), lay their eggs in other bees’ nests.

The much smaller Western honey bees (Apis mellifera) were very numerous. It was interesting to discover that for some time, the NASA website included a section on honey bees! It stopped being updated when the principal investigator retired but NASA maintains the site because of the valued information it contains. Some of the interesting facts they listed about these insects:

  • Bees can fly about 20 mph (32 kph).
  • The highest recorded number of eggs laid by a queen was 2,000 per day!
  • Bees have been on our planet for about 30 million years!
  • To make 1 pound (0.45 kg) of honey, bees need to collect nectar from about 2 million flowers!!
  • The average foraging bee (all females) makes about 1/12th of a teaspoon of honey in her lifetime.
  • The main way in which honey bees communicate among themselves is via chemicals called pheromones.

The honey bees and common Eastern bumble bees make a good choice by spending lots of time in sunflower fields. Scientific studies indicate that ingested sunflower pollen enables them to suffer less infection from two common parasites, a real boon for bees who might otherwise succumb to colony collapse as a result of disease.

 

Both in the sunflower and other fields, it was fascinating to see other types of small bees as well. The small green sweat bees perhaps prefer more colorful blooms as that is where I mostly saw them.

These tiny non-aggressive bees are attracted to sweat because it provides them with moisture and salts.

There were some other interesting insects besides butterflies and bees in the sunflower fields and surrounding vegetation. While looking at some bumble bees circling a large sunflower head, I had inadvertently photographed a pair of much tinier insects near the center of the flower. I actually only noticed them when I was looking at the photos at home or I would have tried to focus on them better in the field.

When I enlarged the photo, I was able to get a somewhat fuzzy look at them and BugGuide identified them for me as sunflower seed maggots (Neotephritis finalis). These tiny insects have prettily patterned wings, but I discovered there is not a lot of information available about them; some research in North Dakota in 2008 concluded they might be a pest but no other data were easily available. They are a species of fruit fly.

Another insect seen on the sunflowers that many people find distasteful were the green June beetles (Cotinis nitida). The larva can damage vegetable and other plant roots, while the adults will feed on ripening fruit, so many gardeners will try to get rid of them.

A cute little syrphid fly, which BugGuide couldn’t identify specifically (a Palpada species), seemed to be alone with no fellow flies nearby.

There were several slender meadow katydids (Conocephalus fasciatus) to admire with their extremely long antennae.

The most interesting fact I discovered about them is that they have a soft song comprising ticks and buzzes that alternate for time periods of 1–20 seconds.

Sunflower fields are beautiful and spending time observing them as interesting wildlife habitats can really be enjoyable. These flowers also constitute a beneficial cash crop for farmers who can sell the seeds for sunflower oil, for human and avian consumption and the stalks for cattle feed.

And as if all those benefits don’t make sunflowers enough of a value-laden plant, scientific studies have also shown that they assist in phytoremediation, a process that helps remove and destroy polluting contaminants in soil, water, and air. Their deep taproots help aerate soil and make it richer for growing other subsequent crops as well.

Some sunflower fields may still be blooming through August and an online search can help you find them if you’d like to enjoy these wonderful flowers and their wildlife beneficiaries. If you have a garden, you might consider adding sunflowers to your vegetation mix if you don’t have them already. You can still plant some now in hopes of late autumn blooms.

This is a good time also to remember that the Ukraine became the world’s leading exporter of sunflower seeds until the currently ongoing invasion of the country brought this trade to a halt. Farmers who were still able to grow the country’s national flower are stuck with supplies and no income. Consider supporting organizations that are working to provide the Ukrainian people with humanitarian aid:

Sunflower fields as critter-friendly habitats — part 1: birds and butterflies

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Last month, many residents of the county where I live were alerted to the eruption of profusely blooming sunflowers that were attracting both birds and people. The avians were looking for tasty seeds, as well as bugs attracted to the blooms, and the humans were seeking beauty and backdrops for photo portraits.

 

Sunflower fields are so popular in our area that they feature on the TV news and in online tourism guides. The NC Museum of Art has sunflower fields and offered a sold-out Sunflower Photography Workshop.

Many birds love sunflower seeds, but it can be difficult to see the foragers as they may be dining at blooms lower down on stems. The bright blue indigo buntings are sometimes easy to spot but I couldn’t get photos of them feeding. Red-winged blackbirds (Agelaius phoeniceus) and American goldfinches (Spinus tristis) will often perch atop a bloom to peck away at the ripening seeds.

   

Other birds were active in the vicinity of the fields, but I didn’t see them at the flowers. For example, the Eastern wood-pewee (Contopus virens) stayed in the vicinity of a nearby pond while I visited.

The Eastern meadowlarks (Sturnella magna) flitted about in nearby meadows. I didn’t see them among the sunflowers.

It’s not only the birds and people that like sunflowers, however. A field of these flowers is a boon for pollinators. The Orange County fields that I visited featured hundreds of butterflies. The most numerous were the orange sulphurs (Colias eurytheme).

As I watched, pairs of sulphurs would often flutter around one another, ascending high up in the air. It was interesting to see that two types of female orange sulphurs were present. Some were yellow-hued like the males; others were whitish in color, known as the Alba variant.

These sulphurs are also known as alfalfa butterflies and the larva is sometimes called the alfalfa caterpillar. An interesting fact about these sulphurs is that the males’ hind wings have an ultraviolet light reflectance pattern, while the females’ hind wings have an ultraviolet absorbing pattern so that they can be distinguished in flight.

Another abundantly present butterfly species were the cabbage whites (Pieris rapae), which were accidentally introduced into North America around 1860. They didn’t seem attracted to the sunflowers per se but instead were fluttering around and landing on the other flowering plants mixed in with them.

Of these small butterflies had me stumped for an ID at first; it was yellowish in color and didn’t have prominent black spots. However, an entomology expert on BugGuide assured me that it was a cabbage white.

Various types of skipper butterflies were feeding on the sunflowers.

There were a few variegated fritillaries (Euptoieta claudia) visiting the sunflowers and an occasional black swallowtail (Papilio polyxenes) fluttered into view as well.

Both the cabbage whites and orange sulphurs were visiting muddy spots at a nearby pond.

This behavior is known both as mudding and mud-puddling and occurs when the butterflies are looking for certain nutrients in mud and rotting plant matter.

Observations have indicated that most of the puddling butterflies are males who often appear to be ingesting salts and amino acids. These substances seem to improve the males’ reproductive success and they transfer these compounds to females when they mate. The nutrients then contribute to the survival of the deposited eggs. Wouldn’t it be interesting if human males could transfer nutritional benefits to offspring in that way?

A latecomer to the puddling parties was a lone common buckeye butterfly (Junonia coenia Hübner). This species generates several generations of offspring each summer and I’m always pleased to see them in my own yard.

Next blog: the sunflower field visit continues with some other numerous visitors!

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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Helping monarch butterflies thrive

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If you follow news about nature, you may have come across warnings that the monarch butterfly (Danaus plexippus) has been in rather dire straits for many years now.

 

These lovely orange and black butterflies live from 6 to 8 weeks when they are adults engaged in reproduction. Those who live in the Eastern USA participate in a multi-generational migration process between Canada and central Mexico. The last generation to emerge in late summer is able to delay its sexual maturity to undertake the last leg of the migratory journey (called reproductive diapause) and may live up to 8 months. Individual butterflies may travel as far as 1200-3000 miles to get to their warmer over-wintering grounds.

 

Since the 1980s, the Eastern US monarch population has declined by about 80%, mainly because the only food source for their caterpillars has been disappearing. Milkweeds used to grow abundantly in agricultural areas and along roadsides and ditches, but people have been eradicating the plants from fields and using herbicides and mowing to remove them along roads.

Climate change has also affected the butterflies’ breeding and migratory patterns so that reproduction has been reduced.

One way to help out the monarchs is to plant native (not exotic!) milkweeds in your own yard and any other natural spaces to which you have access. I’ve been doing it around my home and as a volunteer for the Mason Farm Biological Reserve. This year, I was lucky enough to be a beneficiary of a milkweed give-away organized by some local high-school students, so I had two types of the plants in my yard.

 

The ones that I had originally planted were common milkweed (Asclepias syriaca). These plants have large globular clusters of flowers that range in color from pinkish to purple. They do not have blooms their first year but that doesn’t stop the caterpillars from eating their leaves.

 

Butterfly weed (also known as butterfly milkweed; Asclepias tuberosa) is a bit more delicate and “exuberant” in appearance, with small clusters of orange, reddish and yellow flowers. These were the plants that I was gifted by the students and I was happy to see them grow quickly to exhibit their beautiful blooms.

According to Wikipedia, the butterfly milkweed is not a preferred plant for the monarch but this year the butterflies seemed much more attracted to it than to the common milkweed. After a few visits from some butterflies, I began seeing caterpillars and at one point counted 17 crawling up and down the various plants.

They were especially prevalent on the butterfly weed in my front yard and were munching the plants to bare stems very quickly.

 

       

To make sure they had enough food, I transferred some of them to the common milkweeds in my back yard – these were larger plants with much broader leaves and I thought this would ensure their healthy development. Frass (poop) was being left on the remaining leaves and the ground surrounding the plants.

 

It was rewarding to see three caterpillars make it to the chrysalis stage; the other caterpillars crawled away before I could see where they went, and I didn’t find them suspended from any plants. The first one had attached itself to a bare sapling and, unfortunately, the next day it had disappeared, leaving only the silken thread by which it had been suspended.

The caterpillars store milkweed glycosides in their bodies, making them toxic to many other animals. They still have many predators, however, including wasps, spiders, other insects, lizards, toads and mice. I resolved to save at least one chrysalid if I could.

I got to see the second chrysalis being formed (see the video, which is a little shaky at times). When the caterpillar is ready to undergo the pupation stage, it attaches itself to a plant stem by making a silk pad as an anchor (called a cremaster). Then it inserts the hooks at the end of its abdomen into the pad and hangs down. When the caterpillar forms a J shape, this signals the change to a chrysalis will soon be underway.

Starting from the head, the outer skin is shed, rolling up as the new covering develops. The shed skin may remain at the silk pad or fall off.

 

Slowly the stripes of the caterpillar disappear, and the chrysalis takes on a shiny even green hue, with some golden accent spots.

 

I kept that chrysalis, as well as a third one I saw the next morning, in my house and waited for them to darken. This signals the butterfly is almost through developing inside.

One morning I found the newly emerged monarch from the second chrysalis drying its wings. I took it outside so that it could fly free and then begin its trip to Mexico. (I also took the third one outside when it darkened but the twig holding it disappeared.)

 

You, too, could contribute to their propagation by planting some milkweed if you have an area for this. Autumn is the best time to plant seeds, but you can try it in the spring as well. Common milkweed typically doesn’t flower during its first year, but butterfly weed will give you flowers in its first season; the latter plants may be slow to emerge at first.

Both of these milkweed varieties are perennials so be sure to remember where you planted them. Common milkweed may spread out with time, while butterfly weed remains where you put it.

 

Other flowering plants will attract the adult monarchs, too, for nectaring, such as asters and lantana.

 

And then sit back next year and wait for the monarchs to arrive, happy in the knowledge that you have contributed to maintaining a favorable environment for their survival.

More ideas on how you can participate in the drive to save this iconic butterfly are detailed on a U.S. Fish & Wildlife Service website: https://www.fws.gov/savethemonarch/

 

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!