Tent Caterpillars and Webworms

 

Eastern Tent Caterpillars (Malacosoma americanum)
and web on Black Cherry (Prunus serotina). 
Rowan County, North Carolina.

There are about 12,000 species of moths in North America, and each one comes from caterpillars.  In some species this larval stage is tiny and inconspicuous, others are large and impressive.  While all caterpillars can make silk, a select group weaves a large web to house and protect the larvae.   

Two caterpillars in our area make impressive webs on trees, the Eastern Tent Caterpillar (Malacosoma americanum) and the Fall Webworm (Hyphantria cunea).

A large group of Eastern Tent Caterpillars swarming on
their web.  This tent was made in an ornamental cherry tree (Prunus sp.).
Rowan County, North Carolina. 

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Eastern Tent Caterpillars hatch in spring and build large, tent-like webs at the forks of tree branches. The caterpillars are usually found on trees in the Rose family, the Rosaceae.  We see their webs most often on Wild Cherry (Prunus serotina).  Each web may host several hundred caterpillars.  Eastern Tent Caterpillars go through 6 larval stages called instars. Each instar is larger than the last and the caterpillar molts between these stages.

A sixth instar Eastern Tent Caterpillar feeding on
Black Cherry leaves.
Rowan County, North Carolina. 

The Eastern Tent Caterpillars shelter in the web and crawl out the tree branch to feed on leaves.  The caterpillars eat several times a day and then return to the web. The web controls the temperature and humidity to give the best environment for caterpillar development.   The final instar is about two inches long, dark brown with a white stripe down the middle of the back and blue, black and yellow markings on the side.  Caterpillars of all stages have hairs called setae that help in thermoregulation and may deter predators. Birds are the main predators of Eastern Tent Caterpillars.  The birds prefer the early instars, probably because of the large, irritating setae of later stages.  The final larval stage may wander from the host tree and pupate in a sheltered location.  The moth stage of the Eastern Tent Caterpillar emerges in early spring, lays eggs on a tree and the cycle begins again. 

A sixth instar Tent Caterpillar wandering from the web.  
This one was on a metal fence post. 
Rowan County, North Carolina. 

As their name suggests, Fall Webworms appear in late summer and are present through the fall.  The Fall Webworm Moth lays eggs on the host tree in summer and when the caterpillars hatch, they immediately begin spinning their webs. The webs enclose whole tree branches, including leaves.  The caterpillars eat the soft tissue of the leaves, leaving behind the veins.  Fall Webworms remain within their web to feed and as leaves are consumed, they expand the web to include fresh leaves. Fall Webworms go through 5 larval instars in their development with the final instar being about 1½ inches long, yellow in color with long white setae. 

Fall Webworms (Hyphantria cunea) in their web. 
The host tree of this web was
an Eastern Redbud (Cercis canadensis).
Rowan County, North Carolina. 

Detail of Fall Webworms and web.
Rowan County, North Carolina.

A fifth instar Fall Webworm surrounded by
 earlier larval stages. 
Rowan County, North Carolina. 

Fall Webworms use dozens of deciduous tree species as their host. This fall in our yard they took over branches of Eastern Redbud (Cercis canadensis) and Red Mulberry (Morus rubra).  Birds are major predators of Fall Webworms. Yellow-billed Cuckoos (Coccyzus americanus) on fall migration will tear open the webs and eat dozens of the caterpillars. Fall Webworms are native to North America but have been introduced to Europe and Asia where they are considered invasive species. 

A Yellow-billed Cuckoo (Coccyzus amerianus)
eating fall Webworms.
Orange County, North Carolina. 

 

A fifth instar Fall Webworm outside the web on
Red Mulberry (Morus rubra).
Rowan County, North Carolina. 

While Eastern Tent Caterpillars and the Fall Webworms are superficially similar, they are easy to tell apart.  Eastern Tent Caterpillars appear in early spring and make their webs at the fork of tree branches.  Fall Webworms show up later in the year with webs that enclose branches including leaves.  Both these caterpillars do some damage to trees but do not kill them.  I think these two caterpillars are bookends of the growing seasons of the year.  Eastern Tent Caterpillars to open the spring and Fall Webworms to close out the warm months.  

Video of Eastern Tent Caterpillars 

and Fall Webworms.

Rowan County, North Carolina 

Kudzu and its Bug: A Tale of Two Invasives

 

Kudzu (Pueraria montana)
growing over trees.
Rowan County, North Carolina. 

Kudzu (Pueraria montana) is a famous, nay infamous, invasive vine from Asia.  It was introduced to the United States, like many invasive species, with good intentions.  It was imported as an ornamental plant in the late 19^th century and was used by United States Soil Conservation Service in the early 20^th century to control erosion in the south.  Kudzu is known as "the vine that ate the south" and grows over fields, trees, power poles and buildings. 

A trifoliate compound leaf of Kudzu.
Rowan County, North Carolina. 

Early spring Kudzu vine.
Rowan County, North Carolina. 

Twining vines of Kudzu.
Rowan County, North Carolina. 

Kudzu growing over a house.
Rowan County, North Carolina. 

Kudzu is a member of the Fabaceae, the pea family.  It has large, trifoliate compound leaves and hairy stems. Like many members of this family, Kudzu roots harbor nitrogen fixing bacteria that allows the vine to thrive in even the poorest soils. Kudzu has large tap roots resembling sweet potatoes that are rich in starch. In late summer, Kudzu produces inflorescences of beautiful purple and yellow flowers that smell of grape jelly.   In fall, Kudzu makes a hairy pod containing bean-like seeds.

A Kudzu inflorescence.
The inflorescence blooms from the bottom up.
Rowan County, North Carolina. 

A closeup of a Kudzu flowers.
Rowan County, North Carolina. 

Kudzu fruits.
Rowan County, North Carolina. 

While the plants do make seeds, Kudzu usually spreads by vegetative growth.  Stems that make contact with the soil make new roots and with a growth rate of a foot per day, the vines can ramble long distances in a single growing season.  Kudzu can kill other vegetation including large trees when the leaves and vines block out light and the roots outcompete other plants. 

Kudzu smothering trees.
Rowan County, North Carolina.

Control of Kudzu has proven difficult, and many methods have been tried.  Mowing a stand of Kudzu for several seasons or grazing with goats can remove the invasive plants.  Digging up the vines and herbicide application also works to get rid of Kudzu.  The aerial portions of Kudzu are killed by the first hard freeze and that makes a landscape of brown leaves and vines.  During the winter there is some decay of the dead vines but the following spring the plant begin its relentless growth again. 

A stand of Kudzu in winter.
Rowan County, North Carolina. 

In 2009 a new insect, Megacopta cribraia, started appearing in the counties around Atlanta, Georgia. This invasive insect is called the Kudzu Bug does feed on Kudzu, but it also causes severe damage to Soybean (Glycine max) crops.  Kudzu Bugs are true bugs in the Order Hemiptera and are native to East Asia, the same area that gave us Kudzu.  Kudzu Bugs are small, about ¼ inch long, dark brown and emit a foul, stinkbug-like odor when disturbed. Besides living on Kudzu and eating Soybean plants, this bug is also a pest around homes.  Kudzu bugs are attracted to white or yellow buildings and can congregate in large numbers on houses.  This new invasive insects probably arrived from Asia as stowaways on an airliner.  Since their arrival in 2009 Kudzu Bugs have spread out from Georgia and are now found from Texas to New Jersey and are a major concern for Soybean farmers.  

A Kudzu Bug (Megacopta cribraria) on a Kudzu leaf.
Rowan County, North Carolina. 

A group of Kudzu Bugs on a Kudzu leaf.
Rowan County, North Carolina. 

When Kudzu arrived in North America it found a favorable habitat with few natural enemies, and so it spread. Kudzu now grows from Florida to the Midwest and into Mid-Atlantic states. Contrary to some rumors, Kudzu Bugs were not intentionally introduced to control Kudzu.  Although the bugs do reduce the growth of the vine, it is unlikely this second invasive species will stop the march of  the "vine that ate the south".  

A Kudzu landscape.
Rowan County, North Carolina. 

Some Florida Notes

 

Juvenile Pied-billed Grebe (Podilymbus podiceps).
Green Cay Wetlands, Palm Beach County, Florida. 

Diane and I visited south Florida in August. It was hot.  The low temperatures at night were in the 80s and it went up from there.  These were not the best conditions for nature observation.  Birds were quiet and mammals were hiding out, but we went out each day to visit wetlands.  Even in these steamy conditions we saw some interesting sights. 

Adult Pied-billed Grebe feeding young.
Green Cay Wetlands, Palm Beach County, Florida. 

Many of the birds were still taking care of their last brood of the year.  An adult Pied-billed Grebe (Podilymbus podiceps) was teaching its two babies to catch fish.  The adult would dive, bring up a fish and drop it and let the juveniles try their hand at fishing.  This went on for at least 20 minutes and the fish was getting a little worse for wear by the time we left.  The young Pied-billed Grebes had a striking color pattern with gold, black and white stripes on their heads and pink at the base of their pied bills.  

Common Gallinule (Gallinula galeata).
Green Cay Wetlands, Palm Beach County, Florida. 

 

Adult and juvenile Common Gallinules.
Wakodahatchee Wetlands, Palm Beach County, Florida.

Common Gallinules (Gallinula galeata) and were also busy raising their young.  A baby Common Gallinule still had some downy black feathers and a partially bare head.  Its beak was yellow with a black mark and just a hint of red at the base.  The parent by contrast was dark gray with a yellow-tipped red beak.  Above the beak adult Common Gallinules had a red shield.  This structure is found in certain members of the Rail family, the Ralllidae, and probably functions in attracting mates.  Another striking feature of adult Common Gallinules was their legs and feet.  The toes are long allowing the birds to easily walk across floating vegetation.  The legs and toes are bright yellow with a red band near the body.    

An Black-bellied Whistling Duck (Dendrocygna autumnalis)
admiring the sunrise.
Green Cay Wetlands, Palm Beach County, Florida. 

Back-bellied Whistling Ducks (Dendrocygna autumnalis) were leading their latest offspring.   An adult was waddling through the shallows being trailed by a line of rather large ducklings. These handsome ducks have a gray head, brown body, a pink beak and, of course, a black belly.  The young ducks look much like adults but with a gray beak.  Black-bellied Whistling Ducks were formerly found in the American tropics but have expanded their range through the southern and eastern United States and north into Canada. 

Adult and juvenile Black-bellied Whistling Ducks.
Wakodahatchee Wetlands, Palm Beach County, Florida. 

Least Bitterns (Ixobrychus exilis) are the smallest of our herons.  They have short necks and short legs and spend their time hiding among the reeds.  It is rare to get a good look at one of these shy waders so the day we saw three was a real treat.   A family group was working their way across a marsh jumping between the rushes (Juncus sp.) then flying across short gaps of water to disappear again in the vegetation.

 

Least Bittern (Ixobrychus exilis).
Green Cay Wetlands, Palm Beach County, Florida. 

Dragonflies were active in the summer heat.  These voracious predators flew across the marsh searching for insects and would briefly perch on the tips of plants. Brilliant Blue Dashers (Pachydiplax longipennis) were common with their bright blue bodies and emerald eyes.  

A male Blue Dasher (Pachydiplax longipennis). 
Green Cay Wetlands, Palm Beach County, Florida. 

Four-spotted Pennants (Brachymesia gravida) were abundant in the marsh. Their common name comes from the dark spot on each of the dragonfly's four wings.  They also have a small white spots called stigma on the leading edge near the tip of the wings.  

Four-spotted Pennant (Brachymesia gravida).  This is
a female with light brown wing spots. 
Green Cay Wetlands, Palm Beach County, Florida. 

The most dramatic dragonflies we saw were the Halloween Pennants (Celithemis eponina).  The males are orange with brown wing spots.  This color pattern is reminiscent of Halloween decorations and gives the insect its name. Females are a little less orange but still have the dark wing spots.  Halloween Pennants have the curious habit of perching with their front and back wings held at different angles. 

Halloween Pennant (Celithemis eponina). 
Green Cay Wetlands, Palm Beach County, Florida. 

Halloween Pennant.
Green Cay Wetlands, Palm Beach County, Florida. 

On a boardwalk that crossed a pond, we saw feathers floating on the water.  The first feather was a primary, white with a black tip. It was from a White Ibis (Eudocimus albus).  I thought it had been dropped by a molting bird since they replace their feathers after the breeding season.  Then other feathers started drifting by.  There were more primaries, then secondaries, then body feathers.  This peaceful sight of floating feathers started to look like something darker.  Like leftovers from an alligator's meal. 

White Ibis (Eudocimus albus).
Wakodahatchee Wetlands, Palm Beach County, Florida. 

White Ibis primary feather floating.
Green Cay Wetlands, Palm Beach County, Florida.

White Ibis body feather floating.
Green Cay Wetlands, Palm Beach County, Florida. 

It was fun going out on those slow, hot Florida days.  Several people told us, “Come back in October, when the weather is nicer.”  We will.

 

 

Belize: Plants and People

 

The nut of a Cohune Palm (Attalea cohune).
Lamanai Archeological Site, Belize. 

On a bird watching trip to Belize this summer I would sometimes lag behind the group and talk to one of our guides about the plants.  They had many stories about plants and how the local people use  them.  Plants have been used for centuries by the Maya and others in Central America for food, construction, dyes and medicine.  

Compound leaves of Black Poisonwood (Metopium brownei).
Rio Bravo Conservation Area, Belize. 

Fruits of Black Poisonwood.
Rio Bravo Conservation Area, Belize. 

Belizeans say if you see a Black Poisonwood (Metopium brownei), you will find a Gumbo Limbo (Bursera simaruba) growing nearby.  The Maya say these trees are manifestations of good and bad, and they are always close together.  The Maya name for Black Poisonwood is Chechen and this small tree is found on Caribbean islands, Belize, northern Guatemala and southern Mexico.  Black Poisonwood is a member of the Anacardiaceae, the same family as Poison Ivy (Toxicodendron radicans).  Black Poisonwood produces urushiol, the same toxin found in Poison Ivy.  Human contact with the bark or leaves will raise a rash of itchy blisters that can last for over a week. 

The compound leaves of Gumbo Limbo (Bursera simaruba)
look similar to those of Black Poisonwood.
Rio Bravo Conservation Area. Belize.  

The peeling bark of Gumbo Limbo,
the tourist tree.
Rio Bravo Conservation Area, Belize. 

But growing near Black Poisonwood you will find Gumbo Limbo, Chakaj in Maya.  It is a small tree with red bark that peels off in strips, giving rise to another common name, Tourist Tree.  Local people say the bark looks like a tourist that spent too much time in the sun, red and peeling.  Gumbo Limbo contains a natural remedy for Poisonwood rash.  Irs bark is boiled in water and the liquid is applied to the sores. Gumbo Limbo contains a number of pharmacologically active compounds and has many uses in traditional medicine.  

The giant leaves of a Cohune Palm.
Lamanai Archeological Site, Belize. 

Cohune Palms (Attalea cohune), Mop in Maya, are giants.  The trees may reach 80 feet in height and single fronds can be more than 60 feet long. Cohune Palms produce nuts that are were harvested by the Maya to extract palm oil and the nuts are favorite foods of small rainforest mammals.  The huge fronds are used in making the thatch roofs of buildings.  At the Lamanai Archeological Site is a palapa, a building with open sides and a Cohune Palm roof.  The palapa’s roof was made of 15,000 overlapping Cohune Palm fronds.  Tradition has it that the best time to cut the fronds is during the full moon.  The Lamanai palapa’s roof was made in 1999 so I am sure these fronds were cut during the proper moon phase.    

Palapa with thatch roof made of Cohune Palm fronds.
Lamanai Archeological Site, Belize. 
Photo by Diane Coggin. 

Interior view of palapa thatch roof.
Lamanai Archeological Site, Belize. 
Photo by Diane Coggin. 

Logwood (Haematoxylum campechianum), Ek in Maya, is a small tree with a significant history. This humble tree played a major role in the Golden Age of Piracy, the textile industry in late Renaissance Europe and medical histology. This member of the Fabaceae has compound leaves with heart-shaped leaflets.  Logwood grows along watercourses and other wet areas in Southern Mexico, Central America and Caribbean Islands.  

Compound leaves of Logwood (Haematoxylum campechianum).
Crooked Tree Wildlife Sanctuary, Belize. 

The wood of Logwood is deep reddish orange and the genus name, Haematoxylum, is derived from Greek meaning blood wood.  A dye, hematoxylin, is extracted from the wood and when combined with other chemicals is used to color fabrics red, blue, purple and even black.  In 16th century Europe, brightly colored clothing was reserved for the elite and logwood for dyes was in high demand.  The long-running wars between England and Spain provided opportunities for English pirates to seize Spanish ships carrying all manner of American treasures including Logwood.  Some English pirates decided to eliminate the middleman and became Logwood cutters along the coast of what is now Belize.  These pirates/Logwood cutters are the reason English and not Spanish is the official language of Belize. 

Wood of Logwood.
Crooked Tree Wildlife Sanctuary, Belize. 

Early microscopists including Robert Hooke, one of founders of the discipline, used hematoxylin to stain specimens.  As microscopes improved, practitioners noted hematoxylin preferentially stained cell nuclei.  Hematoxylin is still used to stain tissues for microscopic examination.  One application is the Pap smear.  This test was developed by Dr. George Papanicolaou in the 1920s and uses several stains including hematoxylin to detect precancerous and cancer cells of the cervix.  In a Pap smear, abnormal cells have larger, more darkly stained nuclei and are easily seen. Countless lives have been saved by Pap smears that have Logwood as a central component. 

Cowfoot (Bauhinia divaricata).
Rio Bravo Conservation Area, Belize. 

Cowfoot (Bauhinia divaricata), Zax-suluv-tok in Maya,  is a small tree found from Mexico to Costa Rica and on some Caribbean islands.  It is yet another member of the pea family (Fabaceae).  The common name of Cowfoot comes from the resemblance of its heart-shaped leaves to the hoof print of a cow.  The genus Bauhinia is well known for producing medicinal compounds. These plants have been traditionally used to treat a wide range of conditions from diabetes to diarrhea to kidney disease.  Our guide told us Cowfoot is used by women for birth control.  According to local sources, Cowfoot tea can be used for 8 months to prevent pregnancy but longer use will cause sterility.     

The spiny fruits of Achiote (Bixa orellana).
Rio Bravo Conservation Area, Belize. 

Red seeds of Achiote in the fruit.
Rio Bravo Conservation Area, Belize.

Achiote (Bixa orellana) or k'uxub in Maya, is a small tree native to the American tropics. Bixa orellana is the source of a dye, a spice and a pigment for body paint. The brown, spiny fruits of Achiote contain many small red seeds.  These are ground into a powder called annatto that is added to a variety of foods to add flavor and color. Annatto is still in use as a natural coloring agent for cheese, ice cream, soup and other foods.  One day for lunch at the La Milpa Lodge we were served a soup made with annatto.  This delicious dish contained chicken, egg, onion, pepper and spices including the ground seeds of Achiote as ingredients.      

In the global north we are largely insulated from what the plants around us have to offer. We have systems of agriculture, medicine and technology that allow us to live in ignorance of plants.  But people in other cultures retain an intimate relationship with their plants.  I am always impressed with this deep knowledge and with what we have lost.  

Belizean guides Roni Martinez and Abimael Moralez.

Guide Amir Reyes. 

I would like to thank our guides; Roni Martinez, Abimael Moralez and Amir Reyes for sharing the wonders of the Belizean flora with us. 

A Sensitive Plant

 

Flowers of Sensitive Plant (Mimosa pudica).
Palm Beach County, Florida. 

We usually think of movement as an animal attribute, but plants can move too.  Sure, plants move when they grow, they increase in height or diameter, but some can move rapidly in response to a stimulus.  Sensitive Plant (Mimosa pudica) is an example of a plant with this rapid movement.  Sensitive Plants are members of the pea family, the Fabaceae, and they range through the American tropics and Caribbean islands. They also grow in the Southeastern United States, Africa and Europe.  In the Southeast, Sensitive Plants flower in summer and produce a spherical inflorescence of pink flowers. 

The scientific name of Senstivie Plant, Mimosa pudica reflects its active nature.  Mimosa is from the Greek meaning mime, because the plant mimics the movement of animals. Pudica is from the Latin meaning shy. Another common name for Sensitive Plant is Shame Plant.  The shy and shame in these common names come from the plants ability to quickly close their leaves when touched, as if they want to shrink from sight.  

Compound leaves of Sensitive Plant.
Palm Beach County, Florida.

The leaflets in the center of the photo are 
closing after being touched.
Palm Beach County, Florida. 

Sensitive Plants have compound leaves with many leaflets. Each leaflet has a structure at its base called a pulvinus.  When a Sensitive Plant leaflet is touched, an electrical signal, much like a nerve impulse spreads, across the leaf.  The signal causes the pulvinus cells to lose potassium ions which causes water to leave those cells.  Because of water loss, the pulvinus collapses and the leaflets quickly fold inward.  The signal spreads and a whole section of leaf folds up. 

Video of Sensitive Plant leaflets closing.

Crooked Tree Wildlife Sanctuary, Belize.

The reason for this dramatic action by Sensitive Plants is to startle herbivores and prevent consumption of the leaflets.  You can imagine a rabbit being surprised by this fast plant movement. But if a grasshopper landed on a leaf it could be thrown completely off.  In addition to movement, Sensitive Plants are protected by spines on the stems. 

These interesting weeds grow along roadsides and in sandy soils.  When you find Sensitive Plant, give it a touch and it will show its sensitivity.