Insect Populations Decline In Number And Diversity
Thirteen years ago I went and sat in a field full of Common Milkweed (Asclepias syriaca). The photographs I took of insects visiting the fragrant blossoms ended up being the subject of my first children’s book, Milkweed Visitors. The number and diversity of invertebrates in that patch of milkweed was astounding. Over a decade later I find milkweed flowers alarmingly free of insect visitors. I first noticed this several years ago, and unfortunately the trend has continued. An occasional honey bee or bumblebee, perhaps a swallowtail butterfly or a red milkweed beetle or two can be seen, but nowhere near the number or variety of insects that you found just a few years ago.
Recent studies show that insect populations are declining dramatically not only in milkweed patches, and not only in North America, but in many parts of the world. A global index for invertebrate abundance showed a 45 percent decline over the last four decades. (Yale School of Forestry and Environmental Studies). Researchers say various factors, from the rampant use of pesticides (in particular, neonicotinoids), the spread of monoculture crops such as corn and soybeans, urbanization, and habitat destruction contribute to this decline.
This phenomenon affects everything from pollination to the documented decline in bird populations that feed on flying insects. However, thus far, only the decline of honey bee populations has received widespread public attention, in large measure because of their vital role in pollinating food crops. The rest of the insect world has been widely ignored. Insects play a major role not only in pollination but as predators of insect pests and as food for birds, amphibians and bats. Who knows how many plant species live in symbiotic relationships with highly specialized insects.
Given the importance of insects for agriculture, biodiversity and the health of ecosystems, one hopes that studies regarding the decline of insects will increase in the near future. We can all contribute to a greater understanding of what is happening by participating in “citizen science” projects which undertake monitoring of specific insect species. A list of such projects and how to get involved can be found at https://xerces.org/citizen-science/.
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Common Loon Chicks Hatching
Newly-hatched Common Loon chicks can swim as soon as they hit the water, which they do as soon as their down dries after hatching, usually within 24 hours. Their buoyancy and lack of maneuverability, however, leave them vulnerable to predators. Parents usually don’t stray far from their young chicks due to the omnipresent threat of eagles, hawks, gulls, large fish and snapping turtles. During their first two weeks, young loon chicks often seek shelter (and rest) on the backs of their parents.
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Male Green Frogs Defending Territories
Male Green Frogs are extremely territorial. During June, July and August they establish a series of territories, often claiming each one for less than one week before moving on.
The desirability of a given territory is of utmost importance – the better the quality (amount of vegetation) of your territory the more likely it is that a female will choose you to fertilize her eggs. The more time a male spends in a high quality territory the greater the number of mates he will acquire.
Considerable aggression is displayed against other males when an individual is claiming and maintaining a territory. When a competing male arrives, a wrestling match often ensues (see photo).
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Vulnerable Ducklings
There is a reason why ducklings remain with their mother for their first month or two of life. It takes 50-70 days before most ducklings can fly, and survival during this period is highly variable, ranging from less than 10 percent to as high as 70 percent. They are at their most vulnerable during this stage. The most common causes of duckling mortality include predation, adverse weather conditions, starvation, disease, and parasites. The mother offers her young a degree of protection from some of these factors while they are under her care.
Predation is arguably the greatest threat to young waterfowl. Ducklings are sought after by nearly every type of predator, including other birds (eagles, hawks, owls, herons, crows), fish (largemouth bass and northern pike), amphibians (bullfrogs), reptiles (snakes and snapping turtles), and mammals (foxes, raccoons, and mink). Their odds for survival increase dramatically when the ducklings obtain the ability to fly. (Photo: female Wood Duck and ducklings)
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The Emerald Euphoria Beetle: A Distinctive Scarab
Beetles comprise almost 40% of described insects and 25% of all known animal life-forms. There are about 30,000 beetles known as scarabs or scarab beetles in the family Scarabaeidae. They make up about 10% of all known beetles. You may be very familiar with scarab beetles without even being aware that that is what they are – they are as close as the nearest Japanese Beetle or June Bug (beetle).
Scarabs are generally oval-shaped and stout. The smallest are about .08 inches and the largest (Hercules beetles) can reach 6.7 inches. Most scarabs are black or brown, but many, especially tropical species, have bright colors and intricate patterns. They have distinctive, clubbed antennae composed of plates called lamellae that can be compressed into a ball or fanned out like leaves to sense odors (see photo). Their diet is extremely varied and includes plant material, fungi, fruit, carrion, insects and even the slime left by snails.
One fruit- and flower-eating species is the Emerald Euphoria beetle, Euphoria fulgida (pictured). It is usually bright green or bluish. Emerald Euphoria beetles belong to the subfamily Cetoniiae, the flower or fruit chafers. One of its most distinctive characteristics is its ability to fly (using its second pair of wings) while its first pair (the hardened, colorful elytra) remain closed — most beetles open and extend their elytra during flight.
Unlike most scarabs, Emerald Euphorias are diurnal, making it possible to see this species visiting flowers in order to consume nectar, pollen and petals. (Thanks to Richard Wyatt for photo op.)
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Showy Lady’s Slippers Flowering
Showy Lady’s Slippers (Cypripedium reginae) can be found growing in five of the six New England states (all but Rhode Island). They are ranked as “extremely rare” in three of these states (CT, MA and NH), and uncommon in Vermont and Maine. To gaze upon a flowering clonal cluster of these striking orchids is a thrill no matter where you are in the Northeast.
Given their rarity and distinctive appearance, all populations of Showy Lady’s Slippers are well documented. However, one can still unexpectedly come upon them. In Vermont, where they are on the “List of Rare and Uncommon Native Vascular Plants,” an historical population that had not been seen since 1902 was rediscovered by the Green Mountain National Forest staff in 2009. It consisted of more than 1000 plants.
When you’re traveling through wetlands (forested or open) and moist woods, generally in limy sites, at low to moderate elevations, keep an eye open for these rare beauties. Showy Lady’s Slippers dramatically announce their presence at this time of year with their distinctive and colorful blossoms. (For more natural history on this species, go to the Naturally Curious blog, scroll down and on the right-hand side, search for “Showy Lady’s Slipper.”)
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First Brood of Pearl Crescents Emerging
The first of this summer’s broods of Pearl Crescents are maturing. Our smallest and most common black and orange butterfly can be found throughout the eastern half of the U.S.. This particular species is named after a crescent-shaped spot near the margin of the hind wing on the underside. Its wingspread is about an inch and a half. The exact pattern on its wings is highly variable, making it challenging at times to distinguish it from other crescents.
Asters are the primary food source of Pearl Crescent larvae. Mated females lay their clusters of 20-300 green-yellow eggs on aster leaves, and in roughly a week the brown, black and white spiny larvae emerge. Two broods are common in the Northeast, so one can continue to look for crescent caterpillars on asters into August. Note: The Northern Crescent is very similar-looking to the Pearl Crescent (it may not even be a distinct species). Photo could be of either species. All lepidopterists welcome to comment!
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Bunchberry Flowering
Rarely do you come upon just one Bunchberry (Cornus canadensis), for their underground rhizomes produce colonies of plants, called clones, that are genetically identical to one another (asexual reproduction).
This diminutive member of the Dogwood family is dependent upon pollinating bees and flies for the production of seeds (sexual reproduction). Instead of luring pollinators with showy petals, Bunchberry has four white modified leaves, called bracts, that serve this purpose. (Poinsettia “petals” are also bracts.) The actual petals of Bunchberry are much smaller (about 1/10th of an inch in diameter) and are found in the true flowers clustered in the center of the bracts. Close observation reveals that these tiny petals are very elastic, and when a visiting insect places a foot on one, the petal flips backward, releasing a filament underneath it that snap upwards, flinging pollen out of containers hinged to the filament – an effective means of dusting visiting insects who will further disperse the pollen.
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White-tailed Deer Giving Birth
White-tailed does give birth at the end of May and the beginning of June. A doe giving birth for the first time usually has one fawn; in subsequent years, two or three fawns are common. For the first three or four days after it is born, a fawn is odorless and is well camouflaged thanks to its spotted coat.
During this time the mother leaves her offspring (who remain motionless during her absence) and goes off to feed. (It can be three weeks or so before the fawns follow their mother when she feeds.) The doe stays away as much as possible from her fawns during these first days and weeks to prevent her own body scent from giving away their location. She returns to nurse her young eight to ten times in a twenty-four-hour period.
People discovering what looks to them like an abandoned fawn should know that although the doe may not be in sight, she most likely is within hearing distance and is probably watching them. The fawn has not been abandoned and should not be disturbed. (Thanks to Erin Donahue, who took this photograph.)
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Newly-emerged Dragonflies Vulnerable
When a dragonfly larva crawls up out of the water onto emergent vegetation or a rock to split its skin and emerge as a winged adult, it is in its most vulnerable state, for until its wings are pumped up and dry, it is incapable of flying.
Often for two or three hours a newly-emerged dragonfly will cling to the substrate, pumping hemolymph into its wings until they are fully expanded and then hang there defenseless while its exoskeleton and wings begin to harden. Only then does pigment in the dragonfly’s body become apparent, and its formerly pale, colorless head, thorax, abdomen and wings (see inset) assume their true colors.
The pictured Common Grackle has taken advantage of this precarious stage in a dragonfly’s life cycle and collected several dragonflies to feed to its offspring. The dragonflies’ lack of color indicates that this predation took place while the dragonflies were still flightless and before pigmentation was present.
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Lady Slippers & Resupination
There is just as much learning, or more, going on at my end of this blog as there is at the readers’. A Vermont naturalist recently sent me a photograph of an upside down Pink Lady’s Slipper (Cypripedium acaule). Over 50 years in the field and I have never come across this phenomenon, nor was I familiar with the process that produced it.
Some flowers, including many orchids, are “resupinate.” While the flower is developing, the flower stalk does a 180 degree twist, bringing what would be the bottom of the flower to the top. With lady’s slippers, the labellum, or lip, is inverted, so that it ends up not above the other two petals, but below them. This modified petal, or pouch, serves to attract pollinating insects and acts as a landing platform for them. For some unknown reason, the stalks of the pictured Pink Lady’s Slippers never twisted, allowing us to see the original position of the labellum in both flowers. (Photo by Sue Wetmore)
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Yellow Warblers Courting
Crouching, quivering her wings and issuing forth soft vocalizations, a female Yellow Warbler (in foreground) beckons to her mate, communicating her receptivity to procreation. He proceeds to woo her with a recently-caught Mayfly (insert) which she readily swallows before consummating their relationship. This courtship behavior by the female is practiced by many female songbirds.
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Showy Orchis Flowering
Showy Orchis (Galearis spectabilis), one of the earliest orchids to bloom in the spring, produces a short stalk that rises between two large, glossy, green leaves and bears between two and fifteen flowers. A hood of pink to deep lavender sepals and petals protects the reproductive flower parts; the lower petal is white and spurred, providing a landing pad as well as nectar at the tip of the spur for visiting bumblebees (their main pollinators), butterflies and moths.
Like other orchids, Showy Orchis produces small seeds with no energy reserves. The germinating seedlings need to develop a relationship in their roots with a fungus in order to obtain nutrients for growth. Only certain fungi will develop this relationship, and for Showy Orchis they appear to be only fungi in the genus Ceratobasidium. (Thanks to Erla Youknot and Virginia Barlow for photo ops.)
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