An online resource based on the award-winning nature guide

July

Chestnut-sided Warbler Sitting On Eggs

Different species of birds have different numbers of broods (sets of eggs/young).  Eastern Bluebirds can have up to four broods per breeding season, American Robins up to three and Eastern Phoebes often two.  Chestnut-sided Warblers typically only raise one family in a summer. If weather or predation destroys their first attempt, however, they will re-nest, which is just what the pictured female Chestnut-sided Warbler is doing.

By August, a majority of birds have raised their young, but there are birds that nest late in the season, some naturally (American Goldfinches) and some, such as this Chestnut-sided Warbler, by necessity.  Where birds nest, geographically, affects the number of broods they have. Birds nesting at higher latitudes tend to produce fewer broods per year.  Because it gets colder earlier than further south, there is less time to raise their young.  In warmer regions, birds often raise two or even three broods per year. (Thanks to Dean and Susan Greenberg for photo op.)

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Weevil Watching

If you take a close look at the Black-eyed Susan blossoms that can be found in unmowed fields and roadsides this time of year, chances are good that you will find a tiny beetle called a weevil.  A weevil’s mouthparts are formed into a long snout, with one antenna on either side of it. The snout is used not only for feeding but also for making cavities in buds, fruits, seeds, stems, and roots of plants, where eggs are laid. When the weevil larvae emerge, they feed within the plant.

There are 60,000 species of weevils, all of which are herbivorous and most of which are less than ¼ ” long. Most of those found on Black-eyed Susans appear to be feasting on pollen. Many weevils are pests of plants such as cotton, alfalfa and wheat. You may have even found them inside your house devouring your cereal or flour.

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Beavers Feeding Young

In summer Beavers spend considerable time on land searching for, cutting and bringing vegetation back to their young in the lodge.  Their woody plant preference (they eat large amounts of herbaceous plants during the warmer months, but also some trees) tends towards the inner bark (cambium) of willow, aspen, maple, birch, cottonwood, beech, poplar, and alder trees. This beaver, however, has retrieved a Red Oak sapling for its offspring.

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Caterpillars Eating & Molting

The larval stage of a butterfly or moth is spent doing little but eating.  Only as a caterpillar will these insects have chewing mouthparts, and they waste no time in using them. As they eat, caterpillars increase in size and their skin (exoskeleton) becomes tighter and tighter, as it doesn’t grow larger.  The caterpillar grows a new, larger exoskeleton underneath the outer skin and then sheds, or molts, the old one. Most caterpillars molt five times.  At first, the new exoskeleton is very soft and not very protective, but it soon hardens. The shed exoskeleton is often eaten before the caterpillar ingests more plant food.

There are names for the caterpillar’s stage of development in between each molt, called “instars.”  When the caterpillar hatches from its egg, it is referred to as a “first instar” caterpillar.  After its first molt, the caterpillar is referred to as a “second instar,” and so on up until the exoskeleton is shed for the final time, revealing the chrysalis (if it’s a butterfly).

The Monarch in the photograph is a very new 4th instar instar caterpillar (see antennae which haven’t hardened).  It has shed three times.  Its third exoskeleton (which it has just shed) is on the milkweed leaf behind the caterpillar. To see a real-time video of a Monarch molting go to   https://www.youtube.com/watch?v=EbHyq3RwtxI.

(Thanks to Otis Brown for his keen eye in finding this Monarch caterpillar before it ate its just-molted skin.  Also to Ba Rea ((www.basrelief.org) for her instar confirmation.)

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Predaceous Diving Beetles Seeking Prey

There is a family of water beetles, Dytiscidae, known as Predaceous Diving Beetles.  As their name implies, these beetles are predatory.  They don’t hesitate to attack prey larger than themselves, delivering a sharp bite with their jaws to small fish, tadpoles and frogs.  They then immediately inject enzymes that digest the prey so that the juices can be ingested.

Predaceous Diving Beetle larvae, called “water tigers,” are also predators, grabbing prey with their pincer-like jaws. The larvae are elongated, flattened and can be 2 inches long. They hunt by holding still, waiting with jaws wide open, and then strike suddenly, clutching the prey tightly with their jaws. As with the adults, the pincers are hollow, enabling them to begin sucking the juices of their prey while grasping it. They are often seen when they come to the surface of the water to draw air into spiracles located at the hind end of the body.

Adult Predaceous Diving Beetles are collected by young girls in East Africa. It is believed that inducing the beetles to bite their nipples will stimulate breast growth. Having recently had my toe bitten by a Predaceous Diving Beetle, I can testify that this is not a practice that most females (or males) would enjoy. (Photo: Predaceous Diving Beetle with remains of prey)

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Red Elderberry Attracts Wildlife Year Round

The pollinated and fertilized white flowers of Red Elderberry (Sambucus racemosa) have recently developed into the red fruit for which this plant is named. Many people are familiar with its relative, Common Elderberry (S. canadensis), which produces dark purple fruit that is used to make jams, jellies, pies and elderberry wine.  While Red Elderberry fruit can be used to make all of these, its raw berries are toxic.  Red Elderberry’s popularity is greatest with pollinators, birds and four-footed mammals.

The cyanide-producing toxins in its flowers, (raw) fruit, stems, bark, leaves and roots do not seem to discourage wildlife’s attraction to Red Elderberry.  The odor of its flowers, its nectar, and its highly nutritious pollen attract many ants, bees, wasps and flies.  At least 50 species of songbirds eat the bright red fruits, including red-eyed vireos, ruffed grouse, song sparrows, gray catbirds, brown thrashers, and thrushes. Squirrels, mice, raccoons, and black bears also eat the fruit. Porcupines, mice and snowshoe hares eat the buds and bark in winter. The foliage is usually avoided by herbivores, although white-tailed deer and moose browse on it occasionally.

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Survival Through Mimicry: The Viceroy Butterfly

The survival of Viceroy butterflies in all of their life stages is significantly enhanced by mimicry.  A Viceroy egg resembles a tiny plant gall.  Both larva and pupa bear a striking resemblance to bird droppings.  And the similarity of a Viceroy to a Monarch is well known. For years it was thought that this mimicry was Batesian in nature – a harmless organism (Viceroy) mimicking a poisonous (Monarch) or harmful one in order to avoid a mutual predator.  However, recently it’s been discovered that the Viceroy butterfly is as unpalatable as the Monarch, which means that  mimicry in its adult stage is technically Mullerian – both organisms are unpalatable/noxious and have similar warning mechanisms, such as the adult butterfly’s coloring.

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