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Archive for August, 2015

Black-tipped Darner

black-tipped darner IMG_3123There are two darners that look very much alike, the Black-tipped (Aeshna tuberculifera) and the Shadow Darner (Aeshna umbrosa). The differences are somewhat subtle, so I spent a great deal of time identifying the egg-layers that I photographed for today’s post, vacillating back and forth between the two species. I finally zoomed in on one photo and determined that the lateral stripes on its thorax were outlined in black, making it a Black-tipped Darner (Shadow Darners lack this outline, and lack coloring on the last abdominal segment). That said, while I knew the identity, I neglected to make sure my post reflected this, and once again, a reader was kind enough to point this out. Thank you, Mike Blust!


Darners Laying Eggs

9-1-15 dragonfly laying egg 135Females of different species of dragonfly have different techniques for laying their eggs. Most skimmers, cruisers and clubtails dip the tip of their abdomen to the surface of the water while hovering or flying, and release their eggs. Most darners, such as the Shadow Darner (Aeshna umbrosa) pictured, have a sharp-edged ovipositor with which they slit open a stem or leaf of a plant on or near the water. They then push their egg into the plant tissue exposed by the slit. Because they are stationary during this process, female darners are vulnerable to predation by fish and frogs at this time. A close look at the bottom third of cattail leaves this time of year will tell you whether or not darners are in the vicinity, as the slits they make are very apparent, appearing as thin, tan, 1/2″ vertical lines.

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Velvety Fairy Fan Fruiting

8-27 velvety fairy fan 043Velvety Fairy Fan (Spathulariopsis velutipes) lives up to its name. Its brown stalk is fuzzy, it is tiny and it is shaped like a fan. (It is also called Spatula Mushroom, for equally obvious reasons.) This fungus belongs to the order Helotiales, which also includes earth tongues, jelly drops and other small fungi that grow on plant stems, wood and wet leaves. Because of its diminutive size (3/8” high), Velvety Fairy Fan is often overlooked. The fruiting bodies are often found in clusters that appear in August and September.

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Spiders Molting Exoskeletons

shed spider skin 052Like other arthropods, spiders have a protective hard exoskeleton that is flexible enough for movement, but can’t expand like human skin. Thus, they have to shed, or molt, this exoskeleton periodically throughout their lives as they grow, and replace it with a new, larger exoskeleton. Molting occurs frequently when a spider is young, and some spiders may continue to molt throughout their life.

At the appropriate time, hormones tell the spider’s body to absorb some of the lower cuticle layer in the exoskeleton and begin secreting cuticle material to form the new exoskeleton. During the time that leads up to the molt (pre-molt period), a new, slightly larger, inner exoskeleton develops and is folded up under the existing exoskeleton. This new soft exoskeleton is separated from the existing one by a thin layer called the endocuticle. During the pre-molt period the spider secretes fluid that contains digestive enzymes between the new inner and old outer exoskeletons. This fluid digests the endocuticle that separates the two exoskeletons, making it easier for them to separate.

Once the endocuticle is completely digested the spider is ready to complete the molt. At this point a spider pumps hemolymph (spider blood) from its abdomen into its cephalothorax in order to split its carapace, or headpiece, open. The spider then slowly pulls itself out of the old exoskeleton through this opening.

Typically, the spider does most of its growing immediately after losing the old exoskeleton, while the new exoskeleton is highly flexible. The new exoskeleton is very soft, and until it hardens, the spider is particularly vulnerable to attack.

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Grass of Parnassus Flowering

e-grass of Parnassus 008Grass of Parnassus, Parnassia glauca, (also known as Bog- Star) was named after Mount Parnassus in central Greece. It is not a type of grass, but rather, belongs to the family Celastraceae and can be found growing in fens, bogs and swamps. The striking green lines on its petals guide flies, bees and other pollinating insects to the flower’s supply of nectar.

The structure of Grass of Parnassus’s flower is not typical. In between its five functioning stamens and five petals there is a whorl of five sterile stamens, each of which is three-pronged. The spherical tip of each prong mimics a glistening droplet of nectar. These stamens do not actually produce any nectar – they are there purely to attract pollinators. The actual nectar is located near the base of these false, or sterile, stamens. Only one of the five true stamens in the flower is active at any one time, with each producing pollen on average once every 24 hours.

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Baltimore Checkerspot Larval Diet Not Limited to Turtlehead

8-25-15 B.checkerspot larvae IMG_7102My prior post erroneously stated that Turtlehead (Chelone glabra) was the only host plant of Baltimore Checker larvae. They also feed on Hairy Beardtongue (Penstemon hirsutus), English Plantain (Plantago lanceolata), and False Foxglove (Aureolaria sp.). Thanks to a very astute reader who caught this misstatement!


Baltimore Checkerspot Larvae Feeding On Turtlehead

Baltimore checkerspot larvaeAt this time of year, just as Turtlehead is flowering, a butterfly known as the Baltimore Checkerspot is mating and laying bright red eggs on the underside of Turtlehead’s leaves. This is the only plant on which Baltimore Checkerspot eggs are laid, and the only plant which the larvae eat. When the eggs hatch, the tiny larvae proceed to spin a web that envelopes them and the leaves of the Turtlehead plant that they are eating. They eat profusely, enlarging the web as they expand the area to include uneaten leaves. Eventually, as fall approaches, they will spin a pre-hibernation web where they remain until late fall when they migrate down into the leaf litter. While most butterflies and moths overwinter as eggs or pupae, the Baltimore Checkerspot remains in its larval stage until spring, when it forms a chrysalis, pupates and emerges as an adult butterfly.

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