Thursday, December 14, 2017

Red-Spotted Purple Butterfly

One of the most magnificent woodland butterflies to call Missouri home is the Red-Spotted Purple (Limenitis arthemis). They are now considered to be the same species as the  White Admiral (Limenitis arthemis) and occur throughout the Eastern United States. The species name of "arthemis" comes from the Greek Goddess of the same name, she was the Goddess of the hunt and the wild.  Occurring in woodlands, woodland edges and suburban areas they are a fairly common sight to see in mid-summer through fall. Spotting a flash of bright blue as it wings past you to some unknown destination up ahead is sure to grab your attention.

Historically it was believed that the Red-Spotted Purple and the White Admiral were entirely separate species, but after DNA testing and much laboratory research by individuals who do that sort of thing, it was determined they are the same species. The RSP has iridescent blue or blue-green upperwings, and a dark brown underside. The forewings have two reddish-orange lines near the base of the leading edge; the hindwing has a series of reddish-orange spots marginally and sub-marginally. There is a lot of speculation as to why this species was named Red-Spotted PURPLE, when clearly the wing are bright blue or blue-green.....perhaps the person(s) who were responsible were color-blind?

The WA has a black upperside with broad white bands on both wings. The underside is reddish-brown with white bands that match the upperwings. The wingspan of both species is considered large and may reach up to 4 inches. Males and females look identical, but females are typically larger.
The White Admiral is almost entirely a Northern species whereas the Red-Spotted Purple occurs in the Midwest and upper Midwest. I have never seen a WA and consequently do not have any images of them.

Where their populations overlap it is common for them to interbreed creating various hybrid subspecies that are healthy and capable of reproducing. There are at this time 25 known subspecies in the tribe Limenitidini and they are typically grouped by region. Butterflies in this tribe are often named after military ranks, most likely due to their relatively large size, flight patterns and brilliant colors.  When scientists and researchers were naming these butterflies the light colored stripes on many of the various subspecies wings reminded them of the epaulets worn by admirals and commodores.

It has also been reported that they will interbreed with the Viceroy, which surprised me. Apparently this is a more common occurrence in laboratories  than in the wild where it only happens occasionally.
I would love to see the hybridized offspring of these butterflies though, it would have to be unique and beautiful.

The Red-Spotted Purple is a mimic of the poisonous Pipevine Swallowtail. Just like the Monarch gleans beneficial toxins from the milkweed plant that protect it from predation, the Pipevine Swallowtail gets its toxins from the pipevine plants. The RSP shares coloration so similar to that of the Pipevine Swallowtail that it effectively fools potential predators and gives it some protection from predation. 

Pipevine Swallowtail

Red-Spotted Purple

 Males are extremely territorial and will fight other males who happen to flutter into their personal space. Fights among males may last up to 5 minutes with the loser flying away trying his chances in another area. The victor will gloat over his win and take a victory flight around his territory looking for other interlopers. After mating, the females will deposit eggs on host plants about 2 or 3 feet above ground. It is believed she will lay 2 to 5 eggs daily over the course of two weeks. Exhausted females are often found torn and tattered after such a long laborious process. Host plants include Wild Cherry, Aspen, Poplar, Birch, Cottonwood, Willows, Basswood, Oaks, Shadbush, Deerberry and Hawthorn. There may be two broods per season with the last brood overwintering in tiny hibernacula created out of rolled leaves. When spring arrives the tiny caterpillars will become active as soon as their host plants have greened up giving them a food source to finish their lifecycle. 

These are very active butterflies and somewhat difficult to photograph unless you can find one basking in the sunlight, which they seem to enjoy doing, Adults nectar at tiny white flowers like Spiraea, and Viburnum, but seem to prefer rotting fruit, sap flows, dung and carrion. While these food choices seem distasteful to us humans, there is a lot of valuable nutrition in the form of minerals contained in these unsavory food options that the butterflies benefit from.

Wednesday, December 6, 2017

Eastern Dobsonfly

Eastern Dobsonflies (Corydalus cornutus) look like something out of someones nightmare. They are large, alien-looking, and downright intimidating in their appearance. They measure well over three inches in length and with those sickle-like mandibles, the males are often 4 inches or more. Females lack the longer mandibles, but possess a painful bite when harassed. The larger mandibles of the male lack bite force and are most likely used to impress the ladies or to fight off potential competition from rival males. Some resources claim the males use those mandibles to flip rival males onto their back in a form of combat to win the affection of a nearby female. Apparently these WWE wrestling matches between males weed out the weaker individuals and the stronger, more capable males will mate and have their genetics carried into the next generation.

After mating, females will form egg masses on vegetation near a water source, usually a moving stream or small river. These egg masses are often clustered together as several females will use the same location to lay their eggs, in a type of Dobsonfly rookery. The eggs hatch and the nymphs, called Hellgrammites must find their way to water. Whether they just gracefully fall into the water or crawl their way there is dependent upon how far away from the water the egg mass was formed. Often this can be quite a distance, so dropping into the water would not be an option for those individuals, instead they will have to hoof it to the nearest water source and hope hungry predators don't find them along the way. Once in the water the little Hellgrammites will look for suitable places to hide. Typically this will be under stones and other debris on the bottom of the stream. They lurk about waiting for aquatic insects to come within grabbing range and they will pounce and slink back into the dark recesses of their burrow. With a name like Hellgrammite, it calls to mind images of some great Hell-beast lurking in the depths below the waters surface waiting to wreck havoc. If you are a small aquatic insect these larvae are indeed a beast to be reckoned with, however for humans you've nothing to fear except a resounding pinch from their strong mandibles should you grab one. I found one in the flood waters of the Nodaway River one spring. I had no idea what it was as I watched it wiggle and attempt to swim through the shallow waters covering a county road near the river. I have always been a "I need to touch it kinda person" and this sometimes gets me into trouble. I very quickly realized my mistake as the little bugger bit me resoundingly on the finger as soon as I grabbed it. I dropped it in short order....lesson learned. It was at this point I recognized what it was and gained a healthy respect for them.

Fishermen have used Hellgrammites for hundreds of years as bait to catch trout and other game fish. Trout fisherman create very convincing flies that mimic hellgrammites much to the chagrin of a hungry trout. Many water creatures including salamanders, fish and crayfish all feed on hellgrammites, which might explain why they hide under stones and other debris. 

Once Hellgrammites have had time to grow and reach their full larval size, usually after 12 molts or skin sheds, they will leave the water and look for a place on land to burrow into loose soil where they will create a pupal cell. Once buried and safely ensconced in this chamber they will remain here for 7 to 14 days as they pupate into adult Dobsonflies. When the adults emerge they will begin looking for mates to pass on their genetics to the next generation. Males live about three or four days, females live up to ten days.
In Virginia and Pennsylvania the emergence of the Hellgrammites from their watery homes seems to be synchronous. A mass exodus of these little hell-beasts is usually triggered by a large thunderstorm; it is believed that the vibrations of the thunder acts as some sort of signal to the Hellgrammites to leave the water and head for land. As the larvae crawl out of the watery depths the locals call this phenomena "Hellgrammite Crawling," not to be mistaken for pub crawling.

It is uncommon to find adults during the day as they hide out in vegetation near the water. At night they are attracted to lights and are commonly found at porch lights and other night time light sources. They have also been found to be attracted to Mercaptan which is the substance that is added to Natural gas and Propane that gives it the distinct odor we all recognize as a potential leak. This apparent attraction they have to this substance may act as a calling card to the presence of these gasses. They also seem to prefer moderately clean water environments and do not tolerate highly polluted water. This means they can be used as a bio-indicator of potential health problems within watery habitats. If these insects are present it is a good indication the water is healthy and clean, if not, maybe these environments need a closer looking at.

There are 60 species of Dobsonflies in the order Megaloptera, which means "Large wing." Within this order there are 30 species in the genus Corydalus. The Eastern Dobsonfly is the most common and largest within the United States. They occur throughout Eastern North America from Canada to Mexico. There are three species in the Western United States, however the  majority of species within this genus occur in South America.