Edwards' Hairstreak Butterfly Census 2018

Since I don’t actually count the butterflies or produce any type of tally, my annual observations of the Edwards’ Hairstreak Butterfly can’t really be called a census.  What I do is search appropriate habitat at Blue Jay Barrens to get an idea of current size and distribution of this uncommon butterfly.

Each year, I find butterflies in new locations and in concentrations larger than the year before.

Edwards’ Hairstreak Butterflies were quite rare when I first surveyed this property 33 years ago.  It took years before I found my first specimen.  Subsequent annual searches resulted in sightings of just a few individuals or, in some years, no sightings at all.  Now I can find that many or more sharing a single flower cluster.

One of my first management projects was to make the property more suitable to Edwards’ Hairstreaks.  I cleared Eastern Red Cedar from the fields to promote prairie like habitat, and encouraged the growth of Blackjack Oak, the Edwards’ Hairstreak preferred larval food. 

As habitat improved, the number of butterflies increased.  Nectar plants also responded to the management efforts and increased in number.  Butterfly Weed, a favorite of the hairstreaks, is now common in most areas containing butterfly colonies.

A few years ago it was uncommon to see more than a single Edwards’ Hairstreak on a clump of Butterfly Weed flowers.  Now the butterflies visit the blooms in masses.  There are 10 butterflies clearly visible nectaring on Butterfly Weed in the above photo.  There are still suitable areas not yet being utilized by the butterflies, so butterfly numbers have the potential to increase for many years yet.

The above video shows some Edwards’ Hairstreak nectaring action.  A few Honeybees are also trying grab some of the nectar.  Near the end of the video, one butterfly appears to headbutt another away from his flower cluster.  This video can be viewed on YouTube by clicking HERE.

Edwards' Hairstsreak Larvae - Night Feeding

Within the Blue Jay Barrens prairie openings are a scattering of medium to small sized Blackjack Oaks.  Some of these trees are decades old, but various environmental factors keep them from getting very large.  Dry site conditions limit water available to the tree, White-tail Deer find them to be the perfect choice for rubbing antlers, Periodical Cicadas cause a dramatic die-back every 17 years and a wide variety of insects find the leaves extremely palatable.  I make several close examinations of these trees each spring as I follow the development of the Edwards’ Hairstreak butterfly larvae, one of those species with a dietary preference for Blackjack Oak.

Edwards’ Hairstreak eggs hatch just as the oak buds begin to swell in early spring.  The larvae feed on the buds and newly developing leaves.  On May 8, temperatures dropped to 29°F causing frost and freeze damage to many plants.  Damage to Blackjack Oaks varied between individual trees, but all suffered the loss of some new growth.  This was a setback for both the trees and the Edwards’ Hairstreak larvae.  Fortunately, buds were not affected and regrowth was rapid.

When I checked the Blackjack Oaks three days ago, the leaves were showing signs of heavy predation by the Edwards’ Hairstreak larvae.  When this magnitude of damage occurs to the leaves it is a good indicator that the larvae have reached their final instar stage and will soon be pupating.  At this point it does no good to search the tree for larvae, because they do not spend the day in the open.

Young Edwards’ Hairstreak larvae remain in the open feeding through the day.  When they become older, they feed only at night and spend the day at the base of the oaks, hidden in cavities constructed by Allegheny Mound Ants. 

Near sundown, the larvae leave their shelter and begin climbing the tree.

Each larva is accompanied by its own cadre of ants. From the time they hatch until emergence as adults, the Edwards’ Hairstreaks are accompanied by ants.  The larvae achieve a degree of protection from the ants and the ants receive a sugary Honeydew solution excreted by the larvae.

The larvae on the first tree went too high to be easily observed, so I switched my attention to a smaller tree that displayed feeding activity.  This tree was less than three feet high and struggling to regrow leaves killed by the freeze.

The larva’s head is located near the top of this photo.  As the larva eats, an ant visits honeydew producing glands near the larva’s tail.

It’s fortunate that pupation is near.  This tree was loaded with larvae.  At the rate they’re eating, the tree may soon be stripped bare of leaves.

The above video is a compilation of several shots of moving and feeding Edwards' Hairstreak Larvae.  Make sure your sound is on, so you can enjoy the call of the Chuck-will's-widow while you watch.  This video, in a possibly clearer form, may also be viewed on YouTube by clicking HERE.

Status of Girdled Trees Project

Back in May 2015 I girdled and applied herbicide to the large trees in this area in an attempt to create a grassland corridor between two areas of healthy prairie.  I thought it would be a few years before any of the killed trees began to fall.  Things are progressing much more quickly than I imagined.

In only a year and a half, about a third of the girdled trees have already fallen.  With one exception, all of the fallen trees have been Tuliptrees. 

Some of the trees dropped into the neighboring prairie.  Since this area is still being treated to eliminate invasive shrubs, I’ll remove the fallen trees to make it easier to find and destroy any invading sprouts.

The trees broke just above the girdle ring.  The girdling was done high enough on the trunk that a tall stump remains.  It’s best to leave the stump tall enough to be visible in the grass.  This way you are less likely to fall over or run your mower up onto the stump.

It looks as though the dead trees hosted quite a few wood boring insects.  I was surprised to see the extent to which the wood had been penetrated.

Woodpeckers appear to be taking advantage of the insect laden tree trunks.  I thought some of the trees were large enough to serve as woodpecker nesting sites, but I don’t think they are going to be standing long enough to serve that purpose.  I’m expecting this tree to fall soon.

In June 2016, about a year after being girdled, the Tuliptrees were still producing leaves on a few branches.  I was having some doubts that I had successfully killed the trees.

The trunks themselves gave some positive evidence that I was getting the desired results.  Impressive fungus growths suggested that decomposition was occurring beneath the bark.

A variety of fungus species were present.

I was impressed by the number of fungus species that were able to so quickly take advantage of the recently killed trees.

This area will soon be dominated by tall grass, but it won’t be without a few trees.  I have left several young Blackjack Oaks, Quercus marilandica, to grow among the grass.  Blackjack Oaks have a special relationship with several prairie invertebrates, and are well worth saving.  There won’t be enough trees left to hinder the growth of the prairie grasses, but there will be enough to enhance the quality of this small area.

You can read about the original girdling project by clicking HERE.  

Edwards' Hairstreak Hatchlings

The eggs laid last summer by the Edwards’ Hairstreak butterflies have recently hatched and the buds of the Blackjack Oaks on the barrens are now full of Edwards’ Hairstreak larvae and their attendant Allegheny Mound Ants.

Most of the action takes place on these small Blackjack Oaks. The Edwards’ Hairstreak butterflies sometimes lay their eggs on the larger Oaks, but it’s much more likely that they will use an oak that is less than 6 feet tall.

In order to consume the sweet secretions, called honeydew, produced by Edwards' Hairstreak larvae, Allegheny Mound Ants stand guard and protect the larvae from predators.  The ants protect the larvae from hatching until emergence of the adult butterfly, even though the larvae only produce honeydew during the final few instars prior to pupation.  This type of behavior, where two different species interact to each species benefit, is called mutualism.  In the photo above, two larvae are located just to the left of the ant's head.

The larvae tend to begin feeding at the base of the bud. Leaves that unfurl in a couple of weeks will be laced with holes made by the larvae munching their way through the bud.

Blue Jay barrens has four different Prairie openings that contain quantities of young Blackjack Oaks. I found Edwards’ Hairstreak larvae on trees in all four areas. Some of the buds were really loaded down with larvae. There may not be anything left of these buds to produce leaves later on.

The key to finding the larvae is in finding the ants. If there are no ants on the tree, there are no larvae.  In a couple of cases, ants congregated to protect tree hopper larvae, which also form a type of honeydew. Even in these instances there were butterfly larvae feeding at the same location.

On occasion I would get a bit too close with the camera, causing an ant to take action against me. In each instance, I would direct the ant back onto its bud so it could continue with its duties.

I have been nurturing small Blackjack Oaks at Blue Jay Barrens in hopes of expanding the population size of the uncommon Edwards’ Hairstreak butterfly. I’ve been seeing signs of success during the past couple of years, but this year, the quantity of young larvae far exceeds anything I have seen in the past. The ants have always been present, and now the addition of more trees means more butterflies. The numbers of adult butterflies should be truly amazing this summer.

I’ve included a couple of short videos showing Allegheny mound ants interacting with the Edwards’ Hairstreak larvae. You can watch the above video on YouTube by clicking HERE, or the below video by clicking HERE.

Trees in a Clearing

I always enjoy running across a Beech tree. Across the entire property I’ve probably encountered fewer than a dozen specimens. This is a small example of the species, but it still displays a handsome collection of leaves beginning to show their autumn colors.

I found the Beech growing in this small opening in the cedars. The hole in the canopy isn’t more than 20 feet in diameter and wouldn’t take more than a couple of good trees to fill it. I wonder what the chances are that the Beech could win against its competitors and claim a position in the canopy.

The primary competition for sunlight is going to come from various oaks. This species can be particularly difficult to accurately identify. Although the various characters predominately point to Blackjack Oak, Quercus marilandica; this is a species that crosses to produce a number of different hybrids. Someday I’ll have to spend time studying the different trees to see if I can identify what types of crosses are growing here. Regardless of the parentage, these are rapidly growing trees that would have no trouble overtopping the Beech.

Fragrant Sumac, Rhus aromatica, is a shrub that will not hinder the growth of the Beech. Maximum height of this shrub is usually around ten feet. The branches tend to lean as they grow, so most of the specimens are more sprawling than upright. As an understory species it often supports itself on the branches of taller trees and works its way upward in this manner.

Chinquapin Oak, Quercus muehlenbergii, seedlings can be found just about anywhere at Blue Jay Barrens. This species doesn’t seem to put on the rapid growth of most other oak species. Instead of racing toward the sunlight, Chinquapin Oak progresses slowly and seems to get left behind as stunted specimens in the understory.

Shingle Oak, Quercus imbricaria, is another fast growing oak species. The oaks already have a head start on the Beech and will probably end up shading it as they move to fill the available space. It’ll be a few years before a clear winner will be decided and it’s hard to predict the outcome with any real certainty. The competition should be interesting to watch.

Opening Between the Creeks

This small spot is an area of fairly level soil sitting between two converging streams. There are some shallow depressions and troughs in the ground that suggest this may have been used as a landing for a logging operation some time in the past. I can envision tractors, loaders, and skidders turning and twisting on this spot to get logs into position to be moved out. The depressions hold water long enough to provide suitable conditions for some sedges and rushes to survive.

I’ve seen some odd looking dragonflies along the stream, but they never seem to land and are always moving too fast for me to get a good look. I keep thinking that some of them will make their way into this clearing to sit long enough for me to get a picture. So far none have. I do see the more common species, such as this female Widow Skimmer.

Northern Metalmarks are abundant in this clearing. Some of them are beginning to look a bit worn.

I cleared cedars out of this spot in 1993 and did some maintenance here in 2003. Plants have filled in nicely, but I’m now having trouble with Tulip Poplar. Tulip Poplar can grow very quickly and produce some very dense shade.

I’ll have to get in here soon to clean out these poplars. If these little trees are cut during the winter, they can be successfully killed by an application of glyphosate herbicide in the spring. Timing of herbicide application is critical because the sprouts grow quickly and there is a narrow window between when they are large enough to spray and when they are too large for the spray to be effective.

This Eastern Red Cedar has some sprawling branches that are shading a considerable area. Should I cut the lower branches and expand the size of the clearing or should I leave the branches in place?

Unless I’m dealing with a rare species with an urgent need for more sunlight, I’ll leave the branches in place. These old cedars have developed some interesting ecosystems on their branches. Fungi, lichens, mosses and a variety of associated insects often cover these trees. I’m not yet able to identify most of these, but I feel it’s important to keep them around.

This fallen cedar top needs to be cut up and removed. This is one that broke during the ice storm this winter and waited until early summer to fall. You can see another cedar leaning towards the right. It looks like I’ll be able to get a couple of good fence posts here. Posts are always needed for the never ending task of maintaining property line fence.

There are a lot of small oaks coming into this clearing. This is Shingle Oak, Quercus imbricaria.

An oak that I usually favor in these openings is the Blackjack Oak, Quercus marilandica. Blackjack Oak seems to be the favored species for Edwards’ Hairstreak butterflies at Blue Jay Barrens. An odd thing about this clearing is the absence of Mound Builder Ants. No ants means no hairstreaks, so at this location the oaks could very well be sacrificed for some other species.

Shrubby St. Johnswort, Hypericum prolificum. I love to see the large specimens of this plant all loaded down with blooms. Severe winters and browsing deer keep most of these plants from becoming very large. I hope this one can get some size to it.

Brush piles are located near every opening. I like to think of them as monuments to my efforts. Every pile is tightly packed to encourage decomposition. A typical pile will reduce its size by half in one year. I tried hard to make sure that I didn’t site a pile on top of any significant plant specimens. I’ll pile the cut trees to about 8 to 10 feet high to minimize the area covered by the pile and will move my work to a different opening rather than increase the basal area of the pile.