The perils of being a Monarch

Monarch butterflies have been getting a lot of publicity in the last few years, and rightfully so. They are undoubtedly the best known butterfly in North America and beyond. They are large, easily identified (except for the Viceroy being an excellent mimic) and are known for their incredible journey to the highlands of Mexico to overwinter.

Unfortunately for Monarchs, they rely almost exclusively on milkweeds for laying their eggs and therefore the survival of subsequent generations. For decades, the agricultural community despised milkweeds, as Common Milkweed is an aggressive invader of fields. There are lots of less common species, none of which are particularly problematic to the farming community but all species were painted with the same brush. Between the use of harsh chemicals and being officially on the Noxious Weed List milkweeds, and therefore Monarchs, did not have a promising future.

Fortunately as more and more people realized the serious decline of Monarchs there was a move afoot to remove milkweed from the Noxious Weed List, and more and more people started planting milkweeds in yards and gardens to provide some assistance to the survival of this magnificent butterfly.

The overall results have been fairly positive, with larger and seemingly more stable populations of Monarchs being observed. But every year is different, for different reasons. The limited overwintering habitat in Mexico is not all that secure from impacts. The weather is one of several factors there. Also the long journey by the survivors as they make their way northward in the spring, is not easy. Those that do survive overwinter begin moving north, laying eggs as they go and then dying, counting on the next generation to make the next leg of the trip north. It may take several generations for the species to get all the way back to the northern limits of their usual range.

In some years it seems there are relatively few that arrive here in southwestern Ontario at the beginning of the season, but gradually their numbers increase. In other years, such as 2018, it seemed there was a decent number present in May, leading one to hope for a good population throughout the summer. But it was not to be, at least in this area. The ones that did arrive in good time had some severe weather to contend with once they got here. Not as in stormy, hurricane type weather or cold, frosty weather. No, it was the shift from a cool damp spring to a very hot and very dry period for several weeks in the early part of the summer.

We regularly saw Monarchs in our yard, both male and female, for the early part of the summer. Eggs were laid.

But there were very few caterpillars that matured to adulthood. It was just too hot and dry for them. In fact many butterfly species experienced lower numbers than usual, which was reflected in the results of the annual butterfly counts in mid to late July. Small species of butterfly in particular were affected, but even the large Monarch was affected.

And then by late July and throughout August, we got more rain than usual. Lawns that were brown returned to luxuriant green. Milkweeds were less stressed and provided a better source for caterpillars. The tough, dry leaves of milkweeds responding to the hot dry weather earlier were not suitable for the caterpillars, so many of them did not develop until the moisture levels improved and there were more and younger, fresh leaves to feed on.

Between the milkweeds in and around our yard as well as those in a pollinator patch in a community garden close by, there are well over 125 milkweed stems. We started seeing more and more caterpillars. They developed and formed their trade mark chrysalis.

On one occasion, Marie noted a chrysalis behind a small cage in the garden. The cage was to protect the vegetables from marauding wildlife, such as cottontails. We didn't expect that a Monarch caterpillar would venture here. The nearest milkweed plant was at least 4 metres (12') away. It had to crawl through a lot of grass and other thick vegetation to get to this spot. But there it was.

 The butterfly eventually emerged, and we were concerned that it could not get out without damaging its fragile wings.

 Even though the 'foot' of the chrysalis was attached to the underside of the leaf, it was also attached to the wire of the cage. I decided to carefully tease the foot of the chrysalis away from the wire, and gently lift it outside the cage.

The Monarch managed to continue with its emergence and fluttered away not knowing how close it might have come to a much less desirable end.

As the season continued, we saw more and more caterpillars. On one occasion I could stand at the edge of the pollinator garden and count a dozen caterpillars of various sizes. But there was something concerning about this. None of them were under the leaf, where they would normally be feeding. Instead all of them were quite visible, including some which were just sitting in full view on the upper side of the leaf.

A closer look showed that some of these caterpillars were dead. Almost full size, but quite dead.

We also noticed that at least a couple of recently emerged adults had deformed wings.

One could fly a bit, the other could hardly even remain upright. Clearly something was not going well as both caterpillars and adults were suffering.

Was it something in the air? Were there pesticides that were affecting them? Were they trapped in a place and couldn't emerge properly?

We are not close to any agricultural field, so pesticide drift surely was not a factor. We had no way of testing air quality. We could only surmise that perhaps some caterpillars decided to place their chrysalis in a tight spot and the adults damaged their wings upon emergence.

But that didn't explain the death of so many caterpillars before ever getting to the chrysalis stage.

Marie took it upon herself to see if Google had any answers. And there were some.

Not surprisingly, there are various things that affect Monarch caterpillars, from fungus to bacteria to flies. Yes, flies, and specifically, Tachinid Flies, also known as parasitic flies.

There are more than 1000 species of Tachinid fly in North America, and at a glance they generally look like the flies we are most familiar with. However they do have some differences. These next few photos are all of Tachinid flies, and probably are all different species. A couple of the key features are that they have somewhat hairy bodies and large, reddish-brown eyes.

As adults, the flies feed on nectar of various flowering plants. But it is their reproductive behaviour that is of concern to Monarchs. The flies glue their eggs on to a caterpillar or, depending on the species of fly, sometimes inject the eggs directly into the body of the caterpillar. When the eggs hatch, they begin to feast on the caterpillar and it is doomed. In some cases the eggs are deposited on the surface of the leaf and it is ingested by the caterpillar. In other cases, the Monarch eggs themselves may have a fly egg attached or injected. Regardless, the result is the same. The caterpillar will not develop to a mature adult.

But before we castigate these flies for what we might consider their nefarious deeds, it is important to look at the bigger picture. The term 'fly' is not nearly as endearing as the term 'monarch'. Even the name of the butterfly is regal and something humans may admire. But these flies are not focusing just on Monarch caterpillars. In fact they are a huge benefit to agricultural and garden crops as they parasitize all sorts of other critters, some of which are very harmful. Think of all the damage that pests such as gypsy moths, squash bugs, cabbage loopers, army worms, Japanese beetles, cutworms, sawflies, codling moths, peach twig borers and tent caterpillars do to fruit and vegetables.

Any and every species of wildlife has natural enemies. It is what keeps things in check....the balance of nature, so to speak. If Monarch butterflies weren't so impacted by human activities, such as loss of habitat and the extensive use of harmful chemicals I suspect the effects of Tachinid flies wouldn't be much of a concern. If things were in a truly healthy state, and Tachinid flies weren't affecting Monarch caterpillars, we may be over run with Monarchs! I don't think anyone would complain if there were a lot more than there are, that is for sure. However Tachinid flies are just doing what they were meant to do, and have a place in the wild.

If you have noticed a similar situation in any milkweed patch/pollinator garden that you are involved with, it might be worthwhile to consider this: an emphasis on helping Monarchs is to plant milkweeds and generally speaking, that is a good thing. But if all you have is a big patch of milkweeds, it makes it easier for the flies to find a lot of Monarch caterpillars and eggs. In a truly natural setting, milkweeds are just one of a multitude of grasses and wildflowers, and are seldom in large patches. Instead they are widely scattered, likely giving any caterpillars on them a better chance at being missed by the flies. So add other pollinator plants to the garden patch, and spread out the milkweeds. You just might help a few more caterpillars survive to become a beautiful adult flitting about your yard.

Return of the Dickcissels

They're back! Over the course of the past few days, Dickcissels have returned to places they were present at in 2017. Of course the site just east of Wheatley has had them for a couple of weeks or more this year, but that was a location where they had been present for several years.

2017 was an unprecedented year for them in Ontario, and the southwestern municipalities of Essex, Chatham-Kent and Lambton had the vast majority. Members of the Ontario Field Ornithologists will be aware of the article I wrote in the April, 2018 issue of Ontario Birds discussing the 2017 influx of Dickcissel in Ontario. One of the questions I posed near the end of the article was whether any would return in 2018. The Dickcissel population in the heart of its range had been expanding slowly north and northeast for a few years, and if birds have successfully bred in their newly expanded territory, there would be a good chance they will return the following year. We haven't had the same types of weather yet that 2017 experienced....sustained high winds from the west or southwest.....so any returning birds are likely the result of successful nesting in 2017.

So far Dickcissels have been reported in several places where they were known to have nested the previous year. This includes places in Lambton and Middlesex as well as several places in Chatham-Kent. For example the Campbell Line Pasture just northeast of Blenheim had as many as 19 birds in 2017. So far only one or two birds have been reported this year, but I am not aware of anyone doing a thorough check of this large site. Observations have been from the road only, and that is probably due in part to the presence of large numbers of Wood Ticks. Even if you stay on the grassy laneway, you can encounter a couple of dozen ticks or more in just a few dozen metres or so.

The Dealtown Crown Land prairie (southwest of Blenheim) is another site which had as many as 11 Dickcissels in 2017. I went out a few days ago and came upon at least one and possibly two, males as well as two females. Today some birders went to the site and also saw two males and two females.

It will take a bit of effort to re-visit all of the sites in southern Ontario to see what the return rate might be. I will be keeping a close look at eBird and Ontbirds to document the results.

There are other grassland birds occupying similar sites. Bobolinks and Eastern Meadowlarks are frequently encountered. The former is officially a Species At Risk, so it is nice to see them around in good numbers.

Eastern Kingbirds aren't really a grassland species, but they do like open shrubby areas adjacent to grasslands. I came across several pairs of kingbirds at the Dealtown site.

 Along the trail in to the Dealtown site there were lots of Summer Azures.

A recent, but short, visit to Rondeau didn't turn up any unusual birds. But I did see that Hoary Puccoon is doing well along the grassy beach areas.

A few butterflies were out along the trails there, including:

Red-spotted Purple

Spicebush Swallowtail

Northern Crescent

 I'm a little rusty on my skippers, but I think this next one is a Hobomok Skipper.

I also saw Monarchs, Red Admirals and Eastern Tiger Swallowtails, but didn't get any photos.

On the Monarch theme, a few days ago Marie and I noted a female Monarch busily laying eggs on some of the numerous Common Milkweeds in our yard. I thought they might have hatched by now and did some investigating. Sure enough I found my first Monarch caterpillar of the year.

It is really tiny, measuring not quite 4 mm in total length, so undoubtedly only hatched a day or two ago.

I was up at the Angler Line area to see if the Cattle Egret and Yellow-headed Blackbirds were still around. They were on private property, but the landowner has graciously told me to come by any time. The Cattle Egret has apparently not been seen for several weeks now, but the Yellow-headed Blackbirds are still around at another feeder. One of these days I hope to get my kayak out to see if they are nesting in the maze of cattail islands about half a kilometre off the end of Angler Line. So although I didn't catch up with my target species, I did have the satisfaction of seeing other things.

Yesterday I was at a meeting at a private property just west of Lighthouse Cove, in Essex County. We did spend a bit of time outside, and saw some interesting critters.

An immature Bald Eagle flew by.

 There were two or three Black-crowned Night-Herons.

 It was bright and sunny, so Map Turtles were taking advantage of the conditions.

No more room here!

 Several Northern Water Snakes were also enjoying the sun, including this big female. Since water snakes give birth to live young, they need to bask a lot so that the young are fully developed to result in a successful birth later in August.

 Some water snakes were a little shy.

Transformation of a monarch

It is always fascinating to see the transformation of invertebrate life. In my opinion, there is no more interesting example than to follow the development of a butterfly, and in this case, the Monarch butterfly.

The following images weren't all taken in the last few days, but many of them were. This first one shows an adult female with the tip of her abdomen turned up to the underside of a milkweed leaf as she lays an egg.

 The egg is very small, as to be expected. It is only a couple of millimetres in diameter.

 After a few days, it hatches (hopefully!). Ants are known to find and consume the developing larva, so not all eggs will hatch. Upon hatching, the larva consumes the remains of the egg and will chew a small hole through the leaf.

 This next one shows a larva that is probably 2-3 days old. It hatched out on a small milkweed plant that I was growing from seed in some plug trays.

 Over the course of several days it feeds ravenously.

 After several periods of growth, it gets to the point where it seeks out a place to change to its pupa stage. This usually is in a more obscure location, and often happens well away from the milkweed plant. The caterpillar hangs upside down with its hind end producing a sticky mass of threadlike substance which will provide an anchor, holding it in place while it develops into the adult. While hanging upside down, the caterpillar splits its skin and wriggles out of it, revealing this beautiful chrysalis of the pupal stage. It is decorated with black and gold spots.

When the above photo was taken, it shows a slight darkening of the chrysalis at the bottom. Just before the adult emerges, the outer part of the chrysalis turns clearer and somewhat brown. A close look will show some of the detail and colour of the newly formed adult inside. I wasn't expecting it to happen quite so quickly, and so I missed that part! This next photo was taken less than 24 hours after the one above. The new adult emerges and climbs a bit to a surface where it can hang for several hours while its body fluids are pumped into the venation network making the wings rigid.

 Usually within 4 or 5 hours of emerging, the butterfly is able to take flight and will hopefully survive to continue the propagation process.

It truly is an amazing transformation!

Now that the end of August is close at hand, over the next few weeks, Monarch butterflies will be heading south and west by the hundreds of thousands, on their long journey to the wintering ground in some Mexican mountains. In southwestern Ontario, the peak of their migration seems to occur from about the middle of September to the end of the month, although some individuals can be seen up to the end of October or even after. It all depends on when the latest generation emerges as an adult, which is somewhat weather related. Corridors of natural vegetation and lots of milkweeds are critical for the butterflies to make it to Mexico as well as for future generations to return.

Milkweeds and Monarchs

Milkweeds are nicely coming into bloom these last couple of weeks. There are nine species of milkweed in Ontario, some of which are quite rare. Some of the more common ones include the bright orange Butterfly Milkweed (Asclepias tuberosa) .

 One that is not uncommon, but many people would not notice it, is the Poke Milkweed (Asclepias exaltata), which grows in small numbers along the edges of lush deciduous forests.

 An uncommon species more or less restricted to prairies and savannas is Purple Milkweed (Asclepias purpurascens).

Of course the most common one is, as its name suggests, Common Milkweed (Asclepias syriaca). It is the most aromatic, in my opinion. Fortunately milkweeds were removed from Ontario's Noxious Weed List a little more than a year ago, and that will greatly benefit the declining Monarch butterfly population.

I tried to count the number of Common Milkweeds in my yard....some of which I planted several years ago, and others that just came up on their own. I counted approximately 105 plants, the majority of which will likely flower this year.

More pollinators are found on Common Milkweed than the others, presumably due to their more aromatic nature. Bees, ants, beetles, butterflies all can be found, sometimes all at the same time. But milkweeds can also be traps, as certain sized insects may get their leg trapped in the flower parts and cannot escape. The bee in this next image is one of several bees I have noticed dangling from the flowers in my yard.

Adult Monarchs have not been plentiful yet this year. In fact I have not seen any in our yard, but clearly at least one has been there.

About a week ago, we spied at least 5 good-sized larvae on various milkweeds in our yard, and the neighbours had a couple on theirs as well. They were all about the same size, so it is likely they all were from the successful efforts of a single female Monarch passing through and laying eggs a few weeks earlier.

 A couple of the milkweeds had two larvae feeding on the leaves.

A few days later, they all disappeared. I expect they all left the milkweed plants to find a safe place elsewhere, in order to make their chrysalis where they will develop into an adult.

Go Monarchs!