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Butterflies

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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Black Swallowtails Laying Eggs

6-14-19 black swallowtail 0U1A0073Looking every bit like the Golden Alexander (Zizia aurea) flower buds on which they were laid, the pale yellow eggs of a Black Swallowtail (Papilio polyxenes) are next to impossible to find unless one is fortunate enough to see them in the act of being laid. Members of the parsley family (Golden Alexander, Wild Parsnip, Queen Anne’s Lace, Dill, Carrot) are host plants for most ravenous Black Swallowtail larvae, and thus that is where you will find their eggs. As they eat, the caterpillars absorb toxins from their host plant, which does not harm them but makes them distasteful to avian predators.

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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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