An online resource based on the award-winning nature guide

July

True Bugs

7-15-19 damsel bug 0U1A0251Although the term “bug” is commonly used to refer to just about any insect, there is a specific order of insects (Hemiptera) that are considered “true bugs” and allies. All insects in this order possess a syringe-like beak that they use to suck the liquefied contents out of plants or animals. Their lower lip forms a sheath that contains four blades. One pair of blades (mandibles) is for cutting and the other pair (maxillae) is for spitting and sucking. The maxillae combine to make a tube with two channels, one for sucking food up and the other for spitting saliva (containing enzymes that dissolve tissue) back into the food.

Some of the insect-eating true bugs may be familiar to you – assassin bugs, ambush bugs and damsel bugs (named for their diminutive size) are among them. Nabicula subcoleoptrata (pictured) is a common black, ant-like damsel bug known for its aggressive predation. Look for it in meadows, where it frequently preys on an introduced bug, the Meadow Plant Bug (Leptopterna dolabrata). In this photograph, it has successfully preyed upon and consumed a small larva, identity unknown.

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Lady Fern Spores Maturing

Ferns are non-flowering plants which reproduce by spores, not seeds, and have a vascular system that transports fluids (unlike mosses, algae and liverworts).  Spores are typically located inside a capsule, or sporangium.  In many species of ferns, clusters of sporangia, called sori, are borne on the underside or margins of their fronds.  Often an indusium, or protective flap of tissue, covers each sorus, protecting the developing sporangia.  If you like to be able to give a fern a name, you will find that the shapes and arrangement of sori are a valuable identification tool.

Northern Lady Fern, Athyrium filix-femina, is a fairly common fern found in moist woods, swamps, thickets and fields.  It appears quite lacy and often grows in a somewhat circular cluster.  There are two distinguishing characteristics which are particularly helpful in recognizing Lady Fern.  One is its eyebrow-shaped sori.  If you look on the underside of a spore-bearing frond you will find that each sori is slighted curved, or arched, like an eyebrow.  The other diagnostic feature is the scattered thin, dark brown scales that are found on the stipe – the section of the fern’s stem between the ground and where the leafy frond begins.

This time of year, when the spores of many fern species are maturing, is a good time to learn the different ferns in the Northeast.  There are many excellent field guides to ferns.  One that you can easily tuck into your pocket is Lynne Levine’s Identifying Ferns the Easy Way.

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Common Loon Chicks Riding High

July on a lake occupied by nesting Common Loons is a birder’s slice of heaven.  Eggs are hatching, day-old fluff balls are riding high on their parents’ backs, parents are busy catching and delivering small fish and crayfish to their chicks, and survival lessons are being given. Recently while watching a pair of two- or three-day-old chicks whose parents were off obtaining their offspring’s next meal I observed a juvenile Bald Eagle, known predator of Common Loon chicks, soaring overhead.  Within a split second both loon chicks dove and stayed submerged long enough for the eagle to give up the ghost. Nature or nurture?

To see a related entertaining phenomenon, go to https://loonproject.org/2019/06/29/unlikely-allies/?fbclid=IwAR0po44dJaElcyYpqKqLwaz9A6gs7RxWfhJRkoB-QleC7sUGnjgElksR5G4.

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Monarch Butterfly Larvae Are Cannabalistic

The very first meal that a Monarch Butterfly caterpillar eats is its own eggshell.  In order to hatch, it eats its way out of the egg, and then polishes off the remainder of the eggshell.  It then starts to wander around the leaf and if it finds another Monarch egg, it will start to eat it.

Female Monarch Butterflies lay 300-500 eggs over two to five weeks of egg-laying. Normally, a Monarch only lays one egg at a time (on the underside of a tender, young milkweed leaf).  It is fairly rare to find more than one egg on a leaf, or even on the same plant.  After a female lays an egg, several seconds up to a minute goes by before she lays another egg (referred to as a refractory period). During this time she usually moves on and finds another milkweed plant on which to lay the next egg.  This lapse of time between the laying of each egg probably evolved to discourage the laying of multiple eggs on one leaf and to encourage the dispersal of a female’s eggs on different milkweed plants so as to decrease the chances of cannibalism occurring.

According to Dr. Lincoln Brower, renowned Monarch entomologist, a cluster of Monarch eggs on any given milkweed leaf indicates that either milkweed is in short supply, or the female that laid the eggs is either sick, very old or she has been flying for a very long time and several eggs have matured.

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Bumble Bee-Mimicking Robber Flies

7-10-19 robber fly 0U1A0212Robber flies are a special group of predatory flies that possess stout, spiny legs, a dense moustache of bristles on the front of the head (mystax) that protects the robber fly’s head when it encounters struggling or stinging prey, and three simple eyes in a depression between two large compound eyes.

Certain robber flies resemble bumble bees. The evolutionary advantages of a harmless organism mimicking a harmful organism (Batesian mimicry) include deterring predators that are fearful of stinging bees. In addition, it also makes it more likely that a potential prey insect will come closer to the bee mimic, thinking the “bee” is looking for nectar or pollen, not a meaty meal.

A quick way to distinguish a robber fly from a bumble bee is to look at the antennae and wings. Flies usually have short, stubby antennae; bees, including bumble bees, have “elbowed” antennae (an obvious joint). Flies have two wings, while bumble bees (and most other insects) have four. The pointed, stout proboscis, bearded face, fleshy feet and long, tapering abdomen of robber flies are also identifying characteristics. (Photo: Laphria thoracica piercing a click beetle between the beetle’s hardened outer wings (elytra) in order to inject enzymes which will eventually allow the robber fly to drink its prey.)

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Black Swallowtail Larvae Defending Themselves

7-8-19 black swallowtail larva 0U1A0103Caterpillars, the larval stage of moths and butterflies, are very susceptible to predators (escaping quickly is not an option). Much of their energy in this stage is devoted to defense mechanisms to thwart would-be predators. A partial list of these defenses includes irritating bristles with detachable tips (Tussock Moths), toxic “breath” (Tobacco Hornworms, consumers of tomato plants, tobacco and other plants in the nightshade family, release toxic, bad-smelling nicotine), toxic bodies (Monarchs) and anti-coagulant venom (Giant Silkworm Moths).

Black Swallowtail (Papilio polyxenes) larvae defense mechanism strategies change as they develop. In early stages, or instars, they mimic bird droppings (not an appealing meal for most predators) and older larvae possess bright yellow-orange, horn-like organs behind the head known as osmeteria (see photo inset). When threatened, larvae rear up, extrude the osmeterium, and attempt to smear potential predators with a chemical repellent.

Black Swallowtail larvae are frequently sought after by parasitoids, which can locate their hosts by chemicals in the hosts’ feces (frass). To decrease their chances of being parasitized, Black Swallowtail larvae toss their fecal pellets away from themselves with their mandibles.

To learn much more about both moth and butterfly larvae, go to http://www.thecaterpillarlab.org.

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Pileated Woodpeckers Fledging

7-5-19 junior about to fledge 0U1A0832When your children start to get this feisty, it’s time for them to leave the nest!

Between three and a half and four weeks of age, Pileated Woodpecker nestlings fledge. Their flight feathers are about 75% of adult size when they depart. Some fledglings are capable of sustained flight when they leave the nest, while others may need several days before they can fly any distance.

Initially parents and siblings stay in the vicinity of the nest, but once the young can fly well, they follow adults everywhere. All the young may stay with both parents, or the parents may split up and each take some of the young. The fledglings will remain with their parents into September. (Photo: male Pileated Woodpecker nestling about to fledge while his father watches.) Much gratitude to Amber Jones and Dave Bliven for sharing their deck, their sweet dog Briggs and their magnificent view of this Pileated Woodpecker family with me.

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