2022-23 Monarch Butterfly Winter Numbers Decreased
Every year the Monarch population is estimated by counting the number of hectares (one hectare = 2.5 acres) that contain Oyamel Fir trees inhabited by Monarchs at their central Mexican overwintering grounds. The 2022-23 count which was just released showed a 22 percent decrease from the previous year.
The Monarch population has been declining since counts began roughly 30 years ago. Scientists feel the most important influences are climate change, herbicides and habitat. The weather in the southern United States in the spring, when monarchs are migrating north from wintering in Mexico, is crucial as is summer weather. The creation of genetically modified herbicide-tolerant crops has had a devastating effect on milkweed growth in corn and soybean fields, where it used to flourish. As the Monarchs’ sole source of egg-laying vegetation and larval food, milkweed species are essential to their well-being.
Creating more milkweed habitat appears to be the single most effective way of coming to the Monarchs’ aid. Be it your back yard, school yard, or road sides, disperse those milkweed seeds far and wide! The butterflies that left New England last fall are starting their journey north right now. They will lay eggs and die along the journey, but their offspring will benefit from the efforts we make now. (Photo: Monarchs overwintering on Oyamel Fir trees in the Transvolcanic Mts. of central Mexico; photo and information resource: http://www.journeynorth.org )
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Promethea Moths Pupating
Now is a perfect time to look for cocoons, with leaves off deciduous shrubs and trees. Giant silk moth cocoons are especially evident, due to their large size (often 2″-4″). The Promethea Moth caterpillar (Callosamia promethea), one of several giant silk moths in the Northeast, hatches in the summer and reaches its full size by fall. It then chooses a leaf and reinforces the leaf’s stem, or petiole, with silk so as to make it less likely that the leaf will detach from the branch it is growing on. The caterpillar then spins its silken cocoon inside the curled leaf, and spends the winter pupating inside the cocoon. Look for their well-camouflaged cocoons on low-hanging branches.
Come May or June, the moth will emerge, and if it’s a female, will produce pheromones that may attract males from as far as several miles away.
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Bumble Bee Mouth Parts
Most bumble bees, except for the young queens, have only a few weeks left to live, but until a killing frost arrives, they will be gathering pollen and nectar for themselves and their colony. The various mouth parts that enable them to collect food are hidden behind the large lip that you see when you face a bumble bee head on.
Behind this lip, there are multiple structures that are adapted to grasp, shape and collect food. These include jaws, or mandibles, which clasp pollen and wax used to form cells for eggs. Under the mandibles are two long sheaths that also grasp and shape food called maxillae. Two labial palps located under the maxillae serve as taste sensors. Both of these structures, the maxillae and palps, form a horny sheath which protects the bee’s tongue.
Nectar is accessed with a proboscis which is basically a tube that is protected by the mandible, maxillae and labial palps. A tongue-like structure called a glossa protrudes from the proboscis. Its hairy tip is well suited for collecting nectar.
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Giant Swallowtails Resident Species In Northern New England
Those of us who live in northern New England are enjoying being able to spot the largest butterfly in North America living among us. With a 5 ½” – 7 ½” wingspread, the Giant Swallowtail’s (Papilio cresphontes) common name is very apt. This butterfly has experienced dramatic range expansion in the last decade or so, as it was formerly found only as far north as the mid-Atlantic. Now it is a regular New England inhabitant, primarily due to increasingly warm temperatures, and a common visitor to flower gardens at this time of year.
The larval stage of the Giant Swallowtail is as impressive, or more so, as the adult butterfly. Its defense mechanisms include resemblance to a bird dropping and a forked appendage that emits toxic chemicals (see https://naturallycuriouswithmaryholland.wordpress.com/2012/09/08/giant-swallowtail-caterpillar-defenses/).
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Hummingbird Clearwing Moths Pollinating Flowers
The Hummingbird Clearwing Moth (Hemaris thysbe) is a familiar sight to anyone with a garden full of beebalm, phlox, verbena or butterfly bush. Clearly named after its similar appearance and hovering behavior to hummingbirds (as well as its partially transparent wings where scales have fallen off) this day-flying moth is an excellent pollinator.
Because its tongue, or proboscis, is so long, the Hummingbird Clearwing Moth can reach nectar located at the base of tubular-shaped flowers. If you look closely at this photograph, you’ll see a tiny clump of pollen near the base of the moth’s proboscis. The structure of the Beebalm (Monarda sp.) it’s visiting is such that the stigmas (tips of the pollen-bearing male structures, or stamens) projecting from the upper lip of the flower are located where the moth will come in contact with them as it inserts its proboscis down into the flower’s nectaries. Hummingbird Clearwings carry their proboscis rolled up under their head and unfurl it when approaching a flower. (Thanks to Sally Fellows and Terry Marron for photo opportunity.)
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Ambush Bugs Ambushing
This Eight-spotted Forester Moth, Alypia octomaculata, didn’t have a chance once it decided to feed on the nectar of this Queen Anne’s Lace flowerhead. Hidden below the tiny white flowers waiting patiently for the next unsuspecting visitor was a Jagged Ambush Bug (Phymata sp.). The moth alighted, started drinking and suddenly the ambush bug grabbed the moth with its powerful front legs, injected an immobilizing and digestive fluid, and then drank the liquefying nutrients from the prey’s body. Unlike spiders, which have a pair of fangs, ambush bugs have their mouthparts arranged into a single straw-like beak (visible in photo). As is evident, ambush bugs often capture insects much bigger than themselves.
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Green Lacewings: Active Pest Controllers
Lady Beetles and Praying Mantises are well known to be excellent pest controllers, but there are other insects that are equally beneficial, including Green Lacewings. These distinctive green insects with golden eyes and lacy wings feed mostly on nectar, pollen and honeydew (a sweet liquid excreted by aphids). However, in their larval stage (when they resemble miniature brown and white alligators) they are referred to as “aphid lions” due to their voracious appetite for aphids and other soft-bodied insects.
Lacewing eggs are as distinctive as the larval and adult stages. Each is perched on the tip of a hairlike stalk that is about ½-inch long. Entomologists believe this helps reduce cannibalism of the eggs by sibling larvae.
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2nd Brood of Black Swallowtails Emerging
The process of transforming from a caterpillar to a chrysalis is a miraculous one, but it’s especially intriguing when it comes to Black Swallowtails (Papilio polyxenes). For one thing, their chrysalises vary in color from green to brown, depending on the object on which they choose to attach themselves. Equally impressive, while it is still a caterpillar the Black Swallowtail spins a thread of silk from which it suspends itself. It uses this silk sling as support for the chrysalis that is revealed once the caterpillar splits and sheds its exoskeleton (see it dangling beneath the chrysalis).
The second brood of Black Swallowtails (Papilio polyxenes) is already emerging from their chrysalises this summer, mating and laying eggs during their two week adult life span. Look for the caterpillars dining on members of the Parsley family, including Queen Anne’s Lace, dill, parsley, fennel, celery and carrot foliage. (Photos from left to right: Black Swallowtail larva preparing to pupate, chrysalis (with cast off larval exoskeleton) and adult male Black Swallowtail)
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Mourning Cloak Butterflies Mating
Often the first butterfly you spot in early spring is the Mourning Cloak butterfly. Having overwintered as adults under loose bark, Mourning Cloaks are on the wing as early as March. Due to the lack of nectar-bearing flowers at this time of year, these butterflies seek sustenance from the sap of broken branches. They are still present in April and May when mating takes place, after which they die. The next generation emerges as adults in late May or June, feed and then spend July and August in a state of torpor (estivate). They become active in late August or September and again feed before hibernating in the fall.
Mourning Cloaks are referred to as the longevity champions of the butterfly world, as they live up to ten or eleven months. The life span of a butterfly varies greatly among species, but on average most butterflies live about a month. (Note ragged edge of wings, due to old age.)
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Praying Mantis Egg Cases Overwintering
In the fall, after mating, the female Praying Mantis lays up to 400 eggs in a frothy liquid produced by glands in her abdomen. This one to two-inch long mass is attached to vegetation, often grasses and goldenrod stalks, about a foot or two off the ground. The frothy structure hardens, providing a protective case for the eggs.
In the spring, miniature (wingless) mantises, called nymphs, will hatch from this egg case. When hatching, the nymphs appear all at once, crawling from between tiny flaps in the case and then hanging from silk threads about two inches below the case. Within an hour or two, after drying out, they disappear into nearby vegetation. (Thanks to Jody Crosby for photo opportunity.)
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Winter Cutworms Active In Winter
One of the last things you expect to see on top of snow is a caterpillar, but it can happen. Certain species can withstand the cold of northern New England winters and remain active throughout the colder months. Among them is the “Winter Cutworm,” or larval stage of the Large Yellow Underwing Moth (Noctua pronuba), a relatively common Noctuid (a family of moths that typically has dull forewings and pale or colorful hind wings).
These larvae actively feed on the roots and foliage of plants (grasses, weedy plants and a variety of garden vegetables) through the winter, and on warm days can appear on top of the snow. They pupate and emerge as adults in spring and early summer. (Photo: Winter Cutworm that appears to have been caught short by a sudden drop in temperature.)
Cecropia Moths Mating
Cecropia moths (Hyalophora cecropia) are the largest native North American moths. They are members of a group of moths known as giant silk moths (family Saturniidae), renowned for their large size and showy appearance.
Having overwintered as pupae inside silk cocoons they spun (as larvae) in the fall, the adults emerge at this time of year often during the first spell of hot, humid weather by dissolving one end of their cocoon with their saliva. The female Cecropia emits pheromones at night that are so strong that males can detect them with their feathery antennae from as far as a mile away. Once paired, Cecropia moths proceed to mate for a full day before parting company.
Shortly thereafter the female moth lays up to 100 eggs, often on both sides of a leaf. Due to a lack of functional mouth parts and no digestive system, the adults seldom live more than two weeks after mating. (Photo: female Cecropia moth on left (larger abdomen filled with eggs; narrow antennae); male on right (smaller abdomen; broader, more feathery antennae). Many thanks to Lorraine Vorse for photo opportunity!
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Mourning Cloak Butterflies Emerging
With the recent warm temperatures, Mourning Cloak butterflies have been seen gliding through fields and leafless woods. Unlike most butterflies, Eastern Commas, Question Marks, Red Admirals and Mourning Cloaks overwinter as adults, seeking shelter in protected spots such as under loose bark. When spring arrives, they slip out from their winter quarters and take to the air.
Mourning Cloaks resemble dead leaves so much that from a distance the entire insect seems to disappear when it lands on the forest floor. Up close you can see the velvety texture of the wing scales, said to resemble the clothing mourners used to wear; hence, their common name. Mourning cloaks live up to ten months — an impressive life span for a butterfly. As they age, the yellow border of their wings fades to an off-white.
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Overwintering Moth Larvae Becoming Active
One of the last things one might expect to see on a newly-exposed grassy field in the middle of March is a caterpillar crawling along. This would be unexpected because most moths overwinter as eggs or pupae inside cocoons, not as caterpillars (larvae). Most moths, but not all. Some species of moths overwinter as larvae (and adults).
Tiger Moths (and Tussock Moths) overwinter as caterpillars and pupate in the spring before emerging as adults during the summer. One member of the Tiger Moth group that is familiar to many is the Isabella Tiger Moth, known as the Woolly Bear (Pyrrharctia isabella) in its larval stage. Another member of this group that overwinters as a caterpillar is the Great Tiger Moth (Arctia caja). As early as mid-March you can find both of these caterpillars wandering in search of a protected spot where they will form hairy cocoons that surround and protect their pupal cases. The pictured Tiger Moth adult (Great or Garden Tiger Moth) bears the white geometric stripes that give the members of this group their common name.
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Yellow-bellied Sapsucker & European Hornet Sign
Congratulations to “mariagianferrari,” who came the closest to solving the Mystery Photo when she correctly guessed that the missing bark was the result of a partnership between an insect and a Yellow-bellied Sapsucker (Sphyrapicus varius). The sapsucker arrived first and pecked the vertical rows of rectangular holes in the trunk of the tree in order to obtain sap as well as the insects that the sap attracts. (Usually these holes are not harmful, but a tree may die if the holes are extensive enough to girdle the trunk or stem.)
The second visitor whose sign is apparent between the sapsucker holes is the European, or Giant, Hornet (Vespa crabro). This large (3/4″ – 1 ½ “) member of the vespid family was introduced to the U.S. about 200 years ago. Overwintering queens begin new colonies in the spring and the 200-400 workers of a colony then forage for insects including crickets, grasshoppers, large flies and caterpillars to feed to the larvae.
In addition, the workers collect cellulose from tree bark and decaying wood to expand their paper nest, which is what has occurred between the sapsucker holes, effectively girdling the apple tree. The nutritious sap that this collecting exposes is also consumed by the hornets. We don’t often witness this activity because most of it occurs at night.
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Pollen Baskets
Due to their tolerance of cold temperatures, bumblebees can still be found foraging on late-blooming flowers such as New England Asters (Symphyotrichum novae-angliae). Most worker bees collect and carry pollen in a dense mass of elongated and often branched hairs (setae) on their hind legs called a scopa. Honeybees and bumblebees, however, have pollen baskets, or corbiculae, in which they place and carry pollen back to their hive. Pollen baskets consist of a polished cavity located on the tibia of each of their hind legs which is surrounded by a fringe of hairs. Pollen is pressed on to the pollen basket when it has been collected by the combs and brushes on the inside of the bee’s legs. The bumblebee moistens the pollen with some nectar to make it sticky and stay in the basket. The pollen is loaded at the bottom of the pollen basket, so the pollen that has been pushed towards the top is from flowers the bumblebee visited earliest on her foraging trip. When a pollen basket is full it can weigh as much as 0.01 gram and contain as much as 1,000,000 pollen grains.
Only queen bumblebees overwinter, and they must start a new colony in the spring. When the queen first emerges you can tell whether or not she has started a nest by looking at her pollen baskets. If she is carrying pollen then she has found a nest site.
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Ant Queens & Males Swarming
Ant colonies consist of one or more queens, female workers and males. In most species, only the males and queens have wings. Periodically the winged ants emerge from the colony in large swarms in order to mate. Swarming behavior is usually synchronized with other nearby colonies, so large numbers (hundreds or thousands) of winged ants suddenly appear. After mating, the males die and the queens chew their wings off and use the remaining wing muscles as a source of nutrients during the early stages of establishing a colony.
(Photo: A swarm of ants gathering as they emerge from their ground nest. The pictured (inset) ant has removed three of its four wings and is in the process of removing the fourth wing. Thanks to Alice Trageser for photo opportunity.)
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Male Walkingstick Cerci
Congratulations to Sharon Weizenbaum, Beth Herr and David Ascher for correctly identifying the Mystery Photo as the tip of the abdomen of a Common Walkingstick (Diapheromera femorata), also known as Devil’s Darning Needle, Devil’s/Witch’s Riding Horse, and Prairie Alligator due to its unusual shape. While the Common Walkingstick is a mere 3” long, the largest North American species can grow to 7” and one tropical species may reach 14”.
The Walkingstick lives up to its name – it is easily mistaken for a twig with its slender body and legs. By remaining motionless during the day (or gently swaying in the wind like a leaf or twig would), and feeding on the leaves of various deciduous trees at night it avoids many predators with its physical and behavioral adaptations. The practice of using both camouflage and mimicry is referred to as crypsis.
Both the male and female Walkingstick possess a pair of appendages at the tip of their abdomen known as cerci. The cerci on a female are short and straight, while those on the male are longer and curved. They are sensory organs, but in addition, the male uses his cerci to grasp the female when mating with her (see inset). According to entomologist Dr. Gilbert Waldbauer, the cerci are very effective, allowing the male Walkingstick to clasp the female for many hours (weeks for some species) in order to prevent another male from mating with the female.
This is the time of year you are most likely to notice Walkingsticks, as this is when they are maturing and reproducing. Females drop their eggs to the ground from the canopy and because a portion of the outside (capitulum) of each egg is edible (like the elaiosomes of many spring ephemerals), ants carry the eggs below-ground to their nests and eat the capitulum, leaving the intact eggs to hatch and develop.
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Praying Mantises Preying
Between being able to swivel its head nearly 180 degrees and having two large compound eyes and three simple eyes, the Praying Mantis (Mantis religiosa) misses very few insects within reach. Due to its green or brown coloration, the Praying Mantis is well camouflaged as it lies in ambush or stalks its prey. Spines, tooth-like tubercles and a claw near the tip of each foreleg enable this predator to have a secure grasp on the moths, crickets, grasshoppers, flies, and other insects it consumes. (A Praying Mantis in Pennsylvania was photographed successfully capturing a Ruby-throated Hummingbird.)
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Milkweed Leaf Beetle Survival Mechanism
Many insects use splashy colors and color patterns to defend against being eaten. (This practice is called “aposematism” from the Greek for “away” and “sign.”) If you spend time in a milkweed patch, you’ll notice that several of the insects you see have bright orange and black coloration. Milkweed contains defensive chemicals known as cardiac glycosides and Monarchs as well as several other insects (many of which are black and orange) that feed on milkweed can tolerate them and store these chemicals as a defense. When avian predators consume a Monarch butterfly containing these chemicals, a bird suffers digestive upset.
Once a bird has gotten sick after eating a poisonous black and orange insect such as a Monarch, it tends to avoid any and all insects with similar coloration, regardless of their toxicity or lack of it. Milkweed Leaf Beetle larvae and adults do not absorb the cardiac glycosides in milkweed like a Monarch, so they have no toxic compounds in them and will not poison a predator. Insect-eating birds don’t know this, however, and the beetles successfully deter predation through their coloration.
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Monarchs Starting To Leave Mexico
The Monarchs’ migration north has begun! We are not the only part of the world that is experiencing unusually high temperatures — there has been a heat wave in Mexico this spring where the Monarchs overwinter, and it has them on the move, leaving their sanctuaries and beginning the more than 2,000 mile journey to New England.
This overwintering generation of Monarchs lays eggs in northern Mexico and southern U.S. and then dies. When their eggs hatch and develop into adults, usually by late April to early June, they continue the journey north that their parents began, laying eggs along the way. They begin to arrive in northern U. S. and southern Canada in late May.
To follow their progress northward, go to Journey North’s site, https://maps.journeynorth.org/map/?year=2020&map=monarch-adult-first. Although we probably won’t see any Monarchs in New England until the end of May at the earliest, it’s fun to be able to see exactly how far they have gotten as spring progresses. Journey North citizen scientists also monitor mammals, amphibians and birds. To participate in their research or to see their observations go to https://journeynorth.org/.
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Bumblebees Mating
The adult male bumblebee has only one function in life and that is to mate. However, research shows that only one out of seven males are successful in this endeavor. When mating does take place, it is more complex than one might imagine.
In most species, the male bumblebees fly in a circuit depositing a queen-attracting scent (pheromone) from a gland in their head onto vegetation and prominent structures such as trees and rocks. This usually takes place in the morning, and if it rains, the scent is replaced. The males then patrol the area, with each species of bee flying at a specific height. Once a (virgin) queen has been attracted, mating takes place on the ground or vegetation, and lasts anywhere from 10 to 80 minutes. After the male’s sperm has been deposited he inserts a genital plug in the queen which, when hardened, prevents the sperm of other males from entering her for up to three days. (Photo by Heather Thompson: queen bumblebee with several smaller male suitors)
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Second Generation of Brown-hooded Owlet Moth Caterpillars Active
In the Northeast, Brown-hooded Owlet moths (Cucullia convexipennis) produce two generations a summer. The larvae of the first generation mature in July, and the second generation matures from late August into October. Brown-hooded Owlet larvae are often found on aster and goldenrod plants, resting on stems (often head down) in plain sight during the day. First generation larvae feed on the leaves and the second generation consumes the flowers of these plants. (Photo: note molted skin above caterpillar.)
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Ambush Bug, Not Assassin Bug, In Yesterday’s Post!
Thanks to Pat Nelson’s sharp eyes, I realized I had mislabeled the bug in yesterday’s blog. It was an Ambush Bug, not an Assassin Bug. While both are predators and in the same family (Reduviidae), Assassin Bugs are usually dark colored and have long, narrow heads compared to Ambush Bugs. Ambush Bugs are usually quite stout and typically have bright colors such as yellow, red or orange. They also have thickened front pincer-like legs with teeth-like structures that hold the prey while it is being consumed. Although small (usually less than ½ inch), an Ambush Bug’s prey may be as large as a bumblebee, wasp or butterfly.
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