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Butterflies

A Butterfly’s Proboscis May Act More Like A Paper Towel Than A Straw

9-24-18 sulphur butterfly IMG_9736The chewing mouthparts of a butterfly larva, or caterpillar, undergo changes when the larva develops into an adult butterfly. They are turned into a tube consisting of two parts, or galeae, that when joined form a structure called a proboscis. The proboscis looks like a straw, and has long been thought to act like one. It is often referred to as a sipping tool through which nectar is obtained by butterflies. However, recent discoveries have scientists thinking that the proboscis works more like a paper towel than a straw.

The liquid that a butterfly feeds on in addition to nectar – animal tears, juice inside decomposed fruit, tree sap, sweat, liquid contained in scat – is so viscous that sipping or pumping it through the proboscis, or feeding tube, would require an enormous amount of pressure. It’s been suggested by entomologist Konstantin Kornev of Clemson University that butterflies draw liquid upwards using capillary action – the same force that pulls liquid into a paper towel. The proboscis actually resembles a rolled-up paper towel, with tiny grooves that pull the liquid upwards along the edges, carrying along the bead of liquid in the middle of the tube. (Photo: Sulphur Butterfly on New England Aster)

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Viceroys — Master Mimics

8-17-18 viceroy metamorphosis

A plump caterpillar is irresistible to many insect-eating birds, and some of them (notably Viceroys and Giant Swallowtails) have outfoxed their predators by assuming the appearance of bird droppings, which one assumes is a far less appealing meal.  They do this using color, pattern, choice of resting place and even position – contorting their bodies to match the shape of bird droppings. The Viceroy (Limenitis archippus) uses this technique during its later larval and pupal stages.

The adult Viceroy butterfly also uses mimicry to enhance its survival, but it mimics another butterfly — the Monarch — not bird droppings.  Both the Viceroy and the Monarch are unpalatable and contribute to each other’s protection from birds with this strategy, a relationship known as Mullerian mimicry.

In New England there can be up to three broods of Viceroys, with the larvae of some of the second brood and all of the third brood overwintering and pupating in the spring.

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Eastern Black Swallowtails Laying Eggs

7-23-18 black swallowtail female laying eggs_U1A2171Eastern Black Swallowtail (Papilio polyxenes) butterflies are mating and laying eggs.  The female Eastern Black Swallowtail can appear quite frantic as she visits multiple host plants just long enough to leave a very tiny, spherical, pale yellow egg before heading on to the next plant.  In the wild, Queen Anne’s Lace, Wild Parsnip, Golden Alexander and Poison Hemlock are favorite host plants; in vegetable gardens you frequently find larvae (if you should miss the eggs) on dill, fennel and parsley.  Entomologists have found that host plant odor is one of the cues involved in the Eastern Black Swallowtail’s choice of where to lay eggs.

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First Brood of Pearl Crescents Emerging

6-15-18 pearl crescent_U1A6249The 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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Adult Butterflies Emerging, Mating & Laying Eggs

4-23-18 eastern comma3 0U1A0780Butterflies that remain in New England during the winter spend it in one of many stages – some as eggs, others as larvae or pupae, and a few as adults. Mourning Cloaks, Compton Tortoiseshells, Milbert’s Tortoiseshells, Question Marks, Gray Commas and Eastern Commas all overwinter as adult butterflies. They store fat in their bodies in the fall and replace a portion of the water in their blood with an antifreeze agent, which prevents the lethal formation of ice crystals in their bodies. These butterflies then slip into cracks, behind loose bark, in a hollow tree or some other sheltered spot where they enter a stage referred to as winter diapause. Metabolic and respiratory rates are greatly reduced, and the butterflies remain inactive until the warming, lengthening days of March and April, when they emerge to mate and lay eggs. They often look rather tattered, as they put many miles on their wings the previous summer. Unlike most adult butterflies which live only a few weeks, butterflies that overwinter as adults have a lifespan of eight to ten months. (Photo: Eastern Comma – note white “comma” on under side of hindwing)

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Painted Ladies On Their Way

9-28-17 painted lady2 IMG_1979For the past few weeks we have been witnessing the migration of thousands of southward-bound orange butterflies, a vast majority of which are not Monarchs (although they are having a good year, too) but Painted Ladies (Vanessa cardui). Both their large numbers and the length of time that they have lingered in the Northeast this fall are unusual.

This was a good year for Painted Ladies — they migrated north earlier than usual, arriving in mid-April, possibly giving them time to have an extra generation, reproducing twice instead of once during the summer. In addition, the unusual weather we’ve been having has not been great for migrating. The butterflies have spent a lot of time fueling up on nectar while waiting for a wind out of the Northeast to assist them in their flight to the Southwest. With the prevailing wind change we’re now experiencing, it’s likely many of them will resume their migration today.


Mourning Cloaks Surviving On Sap

4-25-17 mourning cloak IMG_2827

Who doesn’t celebrate at the sight of a Mourning Cloak butterfly gliding through the woods on soft, spring breezes? Because the adults spend the winter hibernating behind loose bark, Mourning Cloaks are among the first butterflies to take flight in the spring. Most butterflies overwinter as eggs or pupae inside chrysalises, and have to complete metamorphosis before they can take to the air.

Surviving in March and April, when there is little, if any, nectar to be found, is challenging. Mourning Cloaks sustain themselves with the sap that exudes from broken tree branches or wounds in tree trunks. Oaks are their preferred source of sap. When they find some, they walk down the trunk to the sap and feed head downward (see photo).

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