Saturday, November 24, 2012

Milkweed's last hooray. Part two

Polished lady beetle (Cycloneda munda) on dying milkweed leaf

The milkweed food chain would be incomplete without predators and parasitoids. Most of them are out of sight in November; but a few are around feeding on whatever is available, mostly aphids.

Multicolored Asian lady beetle (Harmonia axyridis) pupa
Two species of ladybugs or lady beetles find abundant food on the dying milkweeds. A shiny adult polished lady beetle (Cycloneda munda) may be getting ready to hibernate. A little farther a pupa of the multicolored Asian lady beetle (Harmonia axyridis) stays still on a leaf. It is rather infrequent to find one so exposed. This one is darker than most pupae of this species, but as its name indicates, color variations abound. In another month it would become an adult, out of its pupa. It would turn out darker than most of its kind.

Multicolored Asian lady beetle adult

 Another type of aphid eater is present in numbers and feeds on the two species of aphids mentioned in the previous post. The larvae of syrphid flies are blind and worm-like, lacking legs. Despite these disadvantages, they have no trouble finding aphids to feed upon, provided that the mother was careful enough to lay her eggs near a growing and prosperous colony of aphids.
Syrphid larva (Eupeodes americanus)
Syrphid larva (Eupeodes americanus)

It is impressive to see these maggots thrashing around until they find a plump juicy aphid. They hold it with their strong mouth parts and proceed to suck all the internal fluids until the prey is reduced to a deflated piece of skin. You can see the front end of the larva acting as a pump, expanding and contracting. Oddly, the other aphids in the colony have no fear, no premonition of what is in store for them. I have seen them approaching and then walking all over a syrphid maggot in total indifference.

Syrphid larva (Eupeodes americanus)
In a couple of weeks this will be all over. No more active life in the milkweed patch; just a few flying seeds carried by their fluff. The monarchs are long gone. All others remain in the area in hidden places safe from the weather and from the occasional winter predator. They will all return to their usual activities next year, when the milkweeds start sprouting new shoots and providing nourishment to them.

Milkweed's last hooray
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© Beatriz Moisset. 2012 

Tuesday, November 20, 2012

Goats Put to Service at Pennypack

If you go for a walk at Pennypack Ecological Restoration Trust, you may run into some unusual workers recently enlisted to deal with weeds.

My friend and I went there for a walk last Monday and came upon four goats inside an enclosure made of electrified wires. These handsome creatures were merrily munching away brambles, multiflora roses, and oh joy, poison ivy!

Three young men wearing green shirts with the Pennypack logo were putting the final touches on the signs alerting people about the electric wires. We were full of questions for them and were pleased to see them eager to talk.

They told us that restoration programs have started using goats to control invasive vegetation, particularly in the West, and also in Staten Island, New York. Sometimes goats are more effective and more economic than herbicides or weed-whacking. Thus, these fellows convinced the director to start a goat program at Pennypack.

The four goats arrived last Easter and were put to work a month later, after a period of acclimation. Until now they had been doing their weeding job in secluded areas out of sight of visitors. This was their first day in a more visible place by the main trail. It is the visitors' turn to get habituated to the goats and to begin to appreciate their restoration services.

Before and after. November 12, 2012
Before and after. November 16, 2012
Everyday, these eager workers are brought to a patch in need of clearing and left there until dark. They may have to return to the same spot the next day if they haven't finished the job. After that, they are gradually moved to other patches. The goats spend the night in a roofed shelter safe from coyotes. Did you know that there were coyotes in Pennypack? Now you do.

I returned four days later to inspect the progress. The enclosure had been moved a short distance from that of the first day. The happy animals seemed to never stop chomping away at brambles and vines. At first, it wasn't easy to tell what they had accomplished; but after I found my bearings I could see that, in fact, they had disposed of a significant amount of tangled vegetation. They had also munched on the bark of some tree branches. They are not to blame for being so indiscriminate. It is the human handlers' responsibility to place them only where they can do no harm to valuable native plants.

The plan is to restore the goat-cleared areas by replanting them with native plants. This method beats using herbicides. It also beats using human workers, especially when poison ivy is abundant or when the mats of vegetation are impenetrable. Bear in mind that goats may cause damage to valuable plants if given the opportunity; so precautions are needed.

I will continue checking periodically on these four legged employees of Pennypack.

Invasive vines waiting to be disposed of by goats
Beatriz Moisset.11/17/2012
© Beatriz Moisset. 2012

Thursday, November 15, 2012

Milkweed's last hooray

Striped garden caterpillar, Trichordestra legitima

It is November. We are deep into autumn. Monarch butterflies stopped feeding on milkweeds and are long gone from this area. Milkweeds are wilting, dropping leaves, some covered with sooty mold, and others reduced to dry stems and seed pods. Still they continue to nourish and shelter a number of species that depend on them.

A noctuid moth, the striped garden caterpillar moth (Trichordestra legitima), spends the winter as a pupa. An occasional caterpillar hangs around this late in the season taking advantage of the last scraps of food. Unlike monarchs, it is not choosy. This one happens to be feeding on common milkweed but others find nourishment in an incredible assortment of plants, from asparagus to yarrow or tobacco.

Oleander aphid, Aphis nerii

Aphids are busy sucking juices from the few remaining green stems and leaves of milkweeds. Their colonies are usually considerably larger this time of the year. The most frequent species on common milkweed is the oleander aphid (Aphis nerii), a bright yellow-orange one.

Myzocallis asclepiadis
Less common is the aphid called only by its scientific name, Myzocallis asclepiadis, about the same size as the oleander aphid, almost translucent, with dark dots and often seen sharing plants with its more colorful relative. Myzocallis asclepiadis specializes on Asclepias, as its name suggests. The oleander aphid has broader tastes, living on other members of the dogbane family (Apocinaceae), as well as occasionally some plants of the potato family. This aphid is not native to this hemisphere, and, curiously, there are no males in the North American populations, so they only reproduce parthenogenetically or by virgin birth.

Labidomera clivicollis, larva
Labidomera clivicollis
 A colorful beetle, the swamp milkweed leaf beetle (Labidomera clivicollis) is not as selective as its name indicates and also feeds on common milkweed, as this larva was doing. It is unusual to find a larva still feeding in November. There was an adult nearby.

large milkweed bug, Oncopeltus fasciatus
A common denizen of dry and dying milkweeds is the large milkweed bug (Oncopeltus fasciatus). Both adults and juveniles (called nymphs) feed on seeds of this plant as well as leaves. So it is not surprising to see them in large numbers in November.
Soon all these milkweed visitors will be gone, too. The one that will remain will be the longhorned milkweed beetle (Tetraopes tetrophthalmus). Its larvae will remain buried underground feeding on roots and waiting for next spring.

Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2012

Sunday, September 23, 2012

Invisible Bird Food in the Foliage

On a gorgeous end of summer day, I visited the wildflower garden of a local nature center with the intention to capture with my camera some of the wildlife, flower visitors, in particular. Unfortunately, I realized on arrival that I didn't feel well and needed to rest. So I stretched out on a bench under a gazebo, using my handbag as a pillow.

I rediscovered a simple truth: If you remain still and silent, nature comes to you and shows you things that you would have missed otherwise. A toad peeked from under the next bench, remaining in the moist coolness and shadows. Birds sang, flew, and dove into the foliage to emerge again, perhaps near me. A butterfly almost bumped onto my face.

Finally, one of those confusing fall warblers, a Wilson warbler perhaps, landed just ten feet from me. I am hopeless at identifying those drab olive and yellow little fellows. It proceeded to browse delicately from a jewelweed. I wondered what food it could find there. Some detective work was in order. I rested a little longer and then I got up to investigate.

I saw some holes on the leaves. Insects had been feeding; but they were long gone judging by the scar tissue around the wounds. Still the possibility remained that a similar leaf feeder was present when the bird landed. No way to know, though. Also, I couldn't guess whether the long-gone eater had been a caterpillar, sawfly or leaf beetle larva. My detective skills are severely limited in this respect.

Further observation led me to the mummified body of an aphid, not worthy of a bird's attention; but a clue nonetheless. Where there is one aphid, almost invariably there are more. It didn't take me long to find clusters of fat juicy green ones under the leaves of the jewelweed. I would have never noticed the well hidden aphids if the bird had not brought them to my attention.

Although I cannot be sure, I suspect that this was the morsel that the warbler was after. The insect life in the garden is rich and mostly out of sight. It feeds the birds, more skilled than us at spotting this nutritious resource. And thus, the web of life goes on.

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© Beatriz Moisset. 2012

Wednesday, September 19, 2012

Turtles, Shorebirds, and Us

The sun rises above a Florida beach. Dark creatures the size of sand dollars scurry across the sand toward the water: baby turtles, born in the last few hours and rushing toward the safety of the ocean. Many others have taken this road from nest to water line through the night. Darkness provided relative protection from hungry predators. These latecomers face a danger that grows by the minute.

Hundreds of shorebirds have taken notice of the bounty and even invited others with joyous screams. They skillfully dive, beaks and claws at the ready, picking up one delicious morsel after another. Many of the newborns fall prey to the hungry mob, but others pass through the gauntlet and reach the safety of the waves.

You tell me that you worry about the turtles and fear for the survival of the species after reading that populations have been declining steadily. So you chase the birds away.

I tell you that the turtles have been laying eggs on these shores for eons. Birds have been helping themselves to the feast for just as long. They have not driven the turtles to extinction, and they are not likely to do so. They have succeeded in molding the turtle's physiology and behavior, though. That is why most baby turtles emerge at night; that is why they make a dash toward the water; that is why they are shaped the way they are. If raccoons were more abundant than birds, turtles would respond to the nocturnal predation and eventually most of them would emerge during the day rather than at night.  

Nature tends to keep things in balance. In its cruel arithmetic, most babies are not supposed to live. To maintain the turtle populations, all it takes is two hatchlings reaching adulthood and reproducing for each egg-laying female. And each female lays hundreds of eggs not once but many times in the course of her lifetime, most of them doomed to die without reproducing.

No, I say, the most serious threat to sea turtles doesn't come from predators. It comes from us, humans. Pollution, electric lights, heavy beach traffic, both by foot and by vehicles, pets on the loose, fishing nets, human-caused climate change . . . all these things combined put turtles and many other creatures at risk of becoming extinct.

I love the spunky baby turtle and its determination to survive. I also love the graceful seabird that preys on the innocent little turtle. I love all creatures and enjoy their beauty. But I love the web of life even more. Its exquisite quality is hidden from ordinary sight. Understanding it takes observation and careful thought. The marvelous intricacy of the web of life connects all creatures and makes possible their existence. So, you and I would do better to ignore the predatory birds. Instead, let us work together in preventing or mitigating the ecological damage that all of us continue to inflict on the planet.

Beatriz Moisset. Oct. 2012

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© Beatriz Moisset. 2012

Thursday, June 28, 2012

Don't Kill Your Friends

Larva of Coleomegilla maculata, pink spotted lady beetle © Beatriz Moisset
Please, don't go about killing any bug in sight. Some of the ugly ones are your best friends. Take the little "alligator" shown here. If you look closely you will notice that it is devouring aphids.

Same as above, notice the aphids being eaten © Beatriz Moisset
The aphids escape notice at first sight. They are the ones that are sapping the juices from your plants and this little guy is going around vacuuming them as fast as it can.

Adult Coleomegilla maculata on spring beauty © Beatriz Moisset
And here is the kicker, that ugly bug will turn into a ladybug when it is fully grown.And remember that it probably eats more aphids at this stage than when it is fully grown. So, if you think about it, maybe it isn't ugly after all. It is beginning to look rather pretty, don't you think?

Polished lady beetle © Beatriz Moisset

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© Beatriz Moisset. 2012

Tuesday, May 22, 2012

No Tree is an Island

The small seed fell on the fertile soil. After a rest period it swelled and burst out of its case. It lifted its head and began to grow, enjoying the sunshine and the rain water that penetrated the ground and bathed its small roots. After a number of years, it became a significant member of the forest, as large as some of its companions. It had become a tree. And that is what we will call it from now on: Tree.

Tree follows an annual routine, each spring it covers itself with flowers, the agents of a special contract with insect partners. It lures these partners with the perfumed and brightly colored flowers. Tree provides them with nectar and pollen and makes use of them to have its pollen carried to other members of its species. The tiny partners are unaware of the pollination service they provide. Tree uses them for its own purposes, to ensure the next generation and pays them handsomely.

Once the flowers are pollinated, fruits grow, with seeds inside that will complete the process of starting another generation. When the seeds are ready, Tree resorts to other kind of attractants to call a second set of partners. The fruits ripen, become sweet and nutritious and their colors turn bright inviting birds and maybe squirrels or other small creatures as well as larger ones. Tree provides them with sugars and vitamins, to induce them to carry the seeds some distance, so Tree's descendants can spread far and wide.

Tree has relationships with many other members of the forest. Some are not so friendly; they can even be costly.  Tree resorts to other items in its tool kit, including weapons and even hiring some allies of a different sort. Multiple creatures feed on the leaves and other tissues of Tree. Most of the time they don't cause serious damage because Tree uses its defenses to be unpalatable, thus repelling a good number of them or limiting how much they can eat. If things get out of hand Tree resorts to another defense: it calls helpers, parasitic wasps, ready to lay their eggs on the damaging insects, thus bringing down their populations and the damage that they might inflict on Tree otherwise. If that defense isn't enough, Tree can count with the help of several other enemies of its enemies, ladybugs, lacewings and a few others. Tree doesn't know it, but even its enemies may provide it some benefits. Some of them end up feeding the very birds that at other times take care of dispersing Tree's seeds. So, it would be more appropriate to regard them as taxes, that necessary evil, rather than enemies.

Thus, Tree is intertwined to the life of the forest in multiple ways above ground. It is time that we take a look below ground, where the web of life is just as intricate or even more so.

There are certain fungi, called mycorrhizae, that partner with Tree in an intimate way. They are composed of very thin threads similar to rootlets but thinner and far more abundant. They form an endless mesh wrapping around Tree's roots and even penetrating them. They are not a threat but helpers. They dramatically increase the reach of Tree's rootlets and they are far superior at extracting water and essential minerals from the soil.

They render some of these to Tree which, in return, pays its partner with nutrients produced by its leaves. Not satisfied with that, mycorrhizae reach out to other trees and plants, providing similar services. The remarkable thing is that they have the faculty of carrying nutrients from one plant to another when a particular one is under stress and the others are doing well. Thus, the partnership goes well beyond Tree to the entire community.

Mycorrhizal interconnections don't stop there. They also interact with a variety of soil bacteria. These bacteria, too, are very good at producing an assortment of chemicals, some of them useful to the mycorrhizae and also to Tree.

When mycorrhizae want to reproduce, they form the familiar mushrooms often seen on the forest floor. Other mycorrhizae produce truffles instead. Now, it is time for another partner to enter the scene. The mushroom or truffle is nutritious to many forest creatures, beetles, squirrels, flying squirrels. They seek the mushroom or truffle's flesh, swallowing some spores along with it. Later on, they pass the spores at some distance, where new mycorrhizae can grow away from the parent and develop a relationship with other plants.

Tree sheds its leaves every year. These would accumulate to the point of smothering the soil if it wasn't for the work of other helpers. A wide array of insects, fungi, bacteria, nematodes slowly chews away all this matter. It takes them years to return all the nutrients to the soil but they accomplish this task.

I probably left out many other partners of Tree. But this could suffice for now. We can firmly conclude that no tree is an island. No other creature is an island either, all joined together in the Web of Life.

© Beatriz Moisset. 2012

Tuesday, May 08, 2012

Poop Flinging and Other Poop Strategies

Caterpillar shelter
Many insects eat rather non nutritious plant parts. So they need to consume large amounts, extract the nourishment, such as proteins, and discard the rest at the other end. In simpler words: they eat a lot and poop a lot, or if you prefer, they produce large amounts of frass or waste material.
Wasps are some of the worst enemies of caterpillars. They are constantly seeking them to feed their young. Many wasps are superb at controlling insect pests. I would think twice before hurting one of them; they are our friends. Without them, there would be population explosions of plant-eating caterpillars.

Leaf-roller caterpillar and its frass
Caterpillars have devised different ways to hide and keep these ferocious predators from finding them. The so-called leaf-rollers fold a leaf, stitch it together with their silk and stay inside the little tunnel munching away in relative safety. The amount of frass that accumulates inside these little shelters can be impressive. One wonders how they can live in such conditions. Not pretty!

Tiny black dots of frass hurled by caterpillar
Unfortunately for the caterpillar, the smell of their poop is an excellent clue to their presence. You may say that predatory and parasitic wasps have a nose for food-related aromas. So, certain caterpillars have developed a singular strategy. They throw their waste material as far as they can; which can be pretty far. Eight to twelve inches for a caterpillar not much bigger than a grain of rice! That is as if you could throw the you-know-what several yards away.

The curious thing is that many moths and butterflies belonging to different families have come up with the same poop-flinging solution to hide from predators. Among them there is a skipper that you may probably have seen visiting flowers, the silver spotted skipper. It gets its name from the brilliant spot on its hind wings. When this skipper was a caterpillar it regularly shot cannon balls of its own frass as far as a couple of yards away. How about that!
Silver-spotted skipper

Orchard Swallowtail caterpillar 3148
Bird-dropping caterpillar
(by Malcom NQ, Flickr)
Another poop strategy of sorts is that used by many caterpillars called bird-dropping caterpillars. Their appearance, as the name tells you, resembles a bird dropping. Apparently the ruse is convincing enough to discourage would be predators. No real poop is involved here, but it is worth mentioning in an article about poop strategies.

Leaf beetle larva hiding under its poop
And then, there are other insects, particularly a group of leaf beetles that have turned things around completely. Instead of leaving their poop behind, they proudly carry it around as a shield. Some build a sort of basket or nest above and around them. Others have a projection shaped like a coat rack, from which they hang their byproducts, castoff skin and poop. You can read more about one of them in The Poop Bug and the Golden Beetle

More on frass strategies
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© Beatriz Moisset. 2012

Tuesday, March 20, 2012

Food for wildlife

Jan van Huysum. Blumen und Früchte

I invite you to look at this floral painting by the Dutch artist, Jan van Huysum, and find the connection between it and the title of this blog. Look carefully and visit the enlarged version.

Signs of feeding insects

After reading Doug Tallamy's book Bringing Nature Home, I began to see plants with new eyes. The main focus of the book is the importance of native plants in sustaining the food chain by feeding insects and, by extension, all the wildlife that feeds on insects. He points out that, fortunately, insect feeding damage tends to be moderate, as long as the natural systems are in balance. Insects make a little hole here, a little hole there on leaves; or eat an entire leaf; aphids sap juices from plants, etc. But the appearance of the vegetation is not greatly affected and most plants survive and prosper despite such attacks.

A leaf roller caterpillar hiding inside a leaf

Soon after I finished the book, I went on a trip to the Great Smoky Mountain National Park. I noticed, for the first time, something that probably nobody else in my group was aware of. Insects had left traces of their feeding just about everywhere. But, just as Doug mentioned in his book, none of the damage was serious. I saw little holes grouped together, larger holes on other leaves. I saw leaves with nibbled out edges. I saw leaves with translucent spots where the insects had scraped the nourishing in-between tissues, leaving only the outer surface of leaves. I also saw some skeletonized leaves, where only the inedible veins remained. There were some sap-feeding insects here and there, leaf roller caterpillars, interesting galls.

Sometimes I saw a caterpillar hanging from a thread, probably fully grown and ready to bury itself underground to pupate. I know that, for a caterpillar to reach full size, it must have eaten a handful of leaves. I also know that where I see one caterpillar there may be dozens cheerfully disposing of many leaves. So I looked at the canopy and couldn't detect any damage. The foliage overhead was luxuriantly rich and full.

So, it is quite true, the forest feeds the insects and they, in turn, feed all kinds of creatures, big and small. Birds, squirrels, chipmunks, frogs, toads, and lizards take advantage of this rich protein source. Even bears gobble up caterpillars. As long as the ecosystem is healthy, with a good balance of native plants and native animals, you seldom see serious damage. This balance can be disrupted by non-native plants. If they are indigestible to native insects, they suffer no damage; but also they fail to become part of the food chain. They provide no service to the ecosystem that supports them.

Dead hemlock trees

The ecological balance can also be altered by non-native plant feeders, and we saw an example that same day. We arrived at a grove of hemlock trees where the situation was dramatically different. The stately trees ere reduced to skeletons, devastated by a pest. Some were already dead; others were dying. An insidious insect from Asia, the hemlock woolly adelgid, has been accidentally introduced in eastern North America. In its native land this tiny, aphid-like insect causes only moderate damage to the Asiatic hemlocks. The natural resistance of the host plants and other natural controls keep nature in balance. But in this continent the checks and balances are missing; so the adelgid can become a pest that devastates the defenseless trees.

Getting back to the floral bouquet, Dutch artists of the sixteen and seventeen centuries loved to include insects and other small animals into their flower arrangements, not just pretty butterflies but other less popular creatures. They were realistic to the point of showing blemishes on leaves and fruits and also some of the makers of that minor damage.
Jan van Huysum (detail)
 Here is a detail near the bottom of the above painting: a caterpillar on a half eaten leaf. Another example of partially eaten leaves is shown on Balthasar van der Ast's "Still Life with Flowers, Fruit, and Shells"

Balthasar van der Ast. Still Life with Flowers, Fruit, and Shells

You can see the uncropped painting. Then amuse yourself searching for caterpillars or signs of insect feeding on the following Dutch paintings: 1, 2, 3 and 4.

Afterwards, take a walk in the forest and look for similar signs in the foliage. I don't regard them as blemishes any more because they are important components of the web of life. Visualize the caterpillar that made the holes and imagine a parent bird catching the caterpillar to feed its hungry brood.

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© Beatriz Moisset. 2012

Thursday, March 08, 2012

Mycorrhizae and the web of life

A squirrel feeding on mushroom

The role of mycorrhizae in the garden

Mycorrhizae, the symbiotic fungi that feed on organic matter from green plants and, in return, supplies them with water and minerals, is an essential part of an ecosystem. More than 80% of all land plants depend to some extent on mycorrhizae.

In turn, mycorrhizae need the help of some animals to spread the spores. The squirrel is one of these friends of mycorrhizae. By eating mushrooms, the fruiting bodies of mycorrhizae, they take in spores and pass them through their intestines, depositing them later on far from the mother fungus.

A mycorrhizal mushroom

There are opportunists that take advantage of others, in nature as well as in human society. Some green plants have lost their chlorophyll; so they obtain their food from others. This is the case of Indian pipe, a small whitish plant growing among the leaf litter. The above ground part of the plant is just a stem with a few highly reduced and useless leaves and a flower that bends down resembling a pipe, hence the name. Indian pipe's roots extract nutrients from the mycelium of fungi, most commonly mycorrhizal fungi. They, indirectly parasitize the trees that nourish the mycorrhizae.

Indian pipe, a parasitic plant

Root Partners. Mycorrhizae

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© Beatriz Moisset. 2012

Monday, January 09, 2012

Root Partners, Mycorrhizae

The remarkable partnership between plant roots and fungi called mycorrhizae is worth studying. A mushroom is a lot more than a mere addition to the forest floor. Learn more about mycorrhizae

Mycorrhizae, 1
Mycorrhizae, 2 

© Beatriz Moisset. 2012