bugs – Page 7 – Seabrooke Leckie

Monarch chrysalis

November seems to be the time of leftovers and left-behinds, as animals head south, or into hibernation, or otherwise start preparing for winter. November is when I start seeing the summer’s empty birds’ nests, old cocoons, empty shells of things. It’s probably in part because with the animal and plant life disappearing, the eye is drawn more to the inanimate.

I spend a lot of time staring at the ground in November, and so I was doing when I came across this. It was just a bit of curled up paper hidden in the grass, and I nearly dismissed it as a bit of birch bark before pausing for a better look. Stooping down, the bit of paper revealed itself to be an old, long-since-vacated chrysalis. Naturally, I’d left my camera back at the house on this particular outing, so I decided to break off the grass stems and bring it back.

Caterpillar silk is surprisingly strong. I broke off the two grass stems that the chrysalis was obviously attached to, and lifted gently, but there was still another. So I snipped that dead leaf and tugged again, and it was still affixed to something. I broke five bits of grass to finally be able to get it out, and a sixth was hanging by a thread of silk, which I sawed through with a fingernail. No surprise this stuff makes good clothing.

The light was waning when I got back to the house, but I ran off a series of shots. Even though the sides of the chrysalis are in tatters, enough of it remains intact that it’s easy to see the identity of its former occupant: The roundish top, the beaded ring a third of the way down (now lined with black), and the general size all clearly mark this as a Monarch chrysalis. While it housed a metamorphosing caterpillar, it would have been minty green, and that ring of beads was gold.

When I started taking photos, I was surprised by the pattern of black on the top, where it attached to the grass. The stem itself is called a cremaster, and is formed from the tail-end of the caterpillar just before it sheds its skin for the last time. The caterpillar makes a silk “button” then shoves this black rod into it in order to affix itself; once done, it hangs from its tail, curls into a J, and splits its skin along its back. For an amazing sequence of photos, strung into a video, of a Monarch caterpillar changing from caterpillar to chrysalis, you should check out this NPR page, a commentary by Julie Zickefoose. Julie’s also got some amazing transformation photographs at her own blog – here, here and here, for instance. Every year she brings in a couple of fifth-instar caterpillars so her family can watch them metamorphose from larvae to butterflies.

The outside of a chrysalis or pupa is effectively the sixth skin of the caterpillar (it’s already shed five, to get here), rather than an external structure such as the hairy cocoons moth caterpillars make. Because of this, many of the structures of the winged-adult-to-be are defined in its hard shell. With moth pupae, especially, it’s possible to see the shape of the wings and antennae of the adult moth. Butterfly chrysalids need to be more camouflaged and tend to show other shapes (or at least, I presume that’s the reason they show other shapes; they don’t have the same hairy cover that above-ground-pupating moths make).

But I did notice something else on this one: the spiracles that line the abdomen of the insect. Spiracles are the insect’s “nostrils”, the holes through which it breathes. All insects have them, but on many (most?) they’re well-hidden. I thought it was interesting that they were so prominently visible on this old shell; you can see them on the green chrysalis, too, but not as clearly.

And then the other interesting thing I discovered, while poking about BugGuide.net, was mentioned on this photo and this photo… Apparently you can sex the insect inside the chrysalis based on the presence or absence of a small line at the base of the string of black dots. I’ve indicated it in this photo using a yellow arrow. If the line is present, the insect is a female; if it’s absent, the butterfly is male.

This is the first Monarch chrysalis I’ve ever seen in the wild. It would have been more exciting if it had actually contained a Monarch at the time that I found it, but I still think it’s pretty cool!

Broccoli lovers

We were treated to a surprisingly mild day today – around 20°C (68°F), which is beautiful for this time of year. It would have been nicer if it were sunny rather than overcast, but in late October in Ontario you really can’t be picky. I took Raven for a walk (despite that we stayed on our 30 acres, I wore my orange vest just to be on the safe side as I’d heard gunshots from the neighbour’s property earlier in the afternoon) and then bedded down the strawberries before returning indoors.

I never got around to harvesting the last of the broccoli this season. It was my first year growing broccoli, and I kept waiting for it to get a bit bigger, but before it got bigger it would undergo a growth spurt and start flowering. I got a few heads, but the last couple I missed. When they started flowering I decided just to leave them; maybe I could get some seeds off them when they were done.

I noticed, while I was in the garden tending the strawberries, that the plants are still flowering merrily away. Aside from the odd clover here and the stray aster there, they’re pretty much the only thing in the landscape that still is. This fact hasn’t gone unnoticed. The warm weather this afternoon had some late-season pollinators out looking for flowers to forage on, and they’d all converged on this small patch of yellow blossoms. I’d left my camera up at the house while I took the straw down to the garden, and couldn’t resist going back for it to document some of what was crawling over the plants.

There were three bumblebees (three!) visiting the broccoli flowers. At first I thought this one was Tricolored Bumble Bee (Bombus ternarius), by default due to the orange, though there are actually a few species that sport the orange bands on the abdomen. The most common in the east is Tricolored, but we also have B. sylvicola (no common name) and Red-belted Bumble Bee (B. rufocinctus).

I spent a while puzzling over the photos on BugGuide.net, trying to decide what the differences were between the species, before getting frustrated and Googling a North American bumblebee identification page. I discovered this great ID page, which is found at Bumblebee.org. It seems to have originally begun as a UK site – if you Google “bumblebee guide”, most of the first couple of pages are UK sites, and I get the impression they’re much more into their bumblebees there than we are here.

In any case, that fabulous ID key (now bookmarked!) pointed me to Red-belted Bumble Bee, primarily due to the orange butting up against the black on the abdomen – the other species all have a yellow band between them.

Bumblebee species #2 is, I’m fairly certain, a Common Eastern Bumble Bee (Bombus impatiens). This species appears to fly quite late into the fall, with BugGuide having records as late as November for Ontario. It’s also very common, and not at all picky in its habitat or food plant selection. Anywhere and everywhere will do for these guys.

I don’t know about this one. It looks different from #2 – the blacks look blacker, the spot on the thorax larger, a wider band of yellow on the abdomen – but it could simply be individual variation. Or, it could be a male Red-belted, which show no red belt (just black). I think I’m leaning toward Common Eastern, however… it seems like it has a black head, whereas Red-belted would be yellow, I think.

The only other bee visiting the broccoli flowers was this little green sweat bee. There are three genera, all with shiny green representatives, and all looking fairly similar. This individual might be Augochlora… or then again, it might be Augochlorella or Augochloropsis…

This one looks like a bee, but is actually a fly (note the big eyes that touch each other). There are a number of species of flies that are bee or wasp mimics, their disguise providing them with protection against possible predators. Some are incredibly convincing. This one looks to be a member of the genus Eristalis, a group whose larvae are aquatic scavengers.

I was watching another fly when I noticed one of these guys camouflaged against the stem. A green caterpillar, so well hidden it had taken me several minutes before I noticed one. Looking more closely, I ended up spotting half a dozen. There are three species of green caterpillar that might be found on brassicas such as broccoli, but this one, with the thin yellow stripe, will become a Cabbage White butterfly, a very common species.

As I investigated, I spotted one caterpillar who was receiving some special attention from a little fly. It took a bit of hunting, but I believe the double-bulbed abdomen makes this a black scavenger fly, a member of the family Sepsidae, and probably within the genus Sepsis. Google “sepsis fly” and you get quite a number of results of studies looking at copulatory behaviour in the genus… From what I can tell, however, the family are more interested in dead than live material for laying their eggs on/in, and so this guy may not have had any real interest in the caterpillar after all.

Then there was this little wee guy. This one really is a species of ichneumonid wasp, and really is parasite of other insects. There are quite a number of species of ichneumonids, and I’m not precisely sure which this might be. I suspect, however, Hover Fly Parasite (Diplazon laetatorius), based on the black body and red legs with white stripes. It’s a widespread species that parasitizes the larvae of a wide variety of fly species.

These hemipterans weren’t new for me, though I had to look up their names again. Tarnished Plant Bugs (Lygus lineolaris), or perhaps a related species. It’s a fairly widespread species in the east, and adults are active most of the year, into quite late in the fall. Their larvae are generalists, but particularly like agricultural and commercial crops such as soybean and cotton (and, apparently, broccoli).

And the final critter crawling about the flowers was this tiny moth. It’s a Diamond-back Moth (Plutella xylostella), an introduced species that was probably accidentally imported in the mid-1800s. Caterpillars feed on plants in the family Cruciferae which – you guessed it – includes broccoli. Unsurprisingly, adults occur wherever these crop plants are grown (pretty much everywhere), and have a very long flight season.

Canada Darner

A few days ago Dan pointed out a dragonfly that was sunning itself on the screening of the window at the front of the house. Or at least, it looked like it was sunning, on the south-facing side with its wings spread. Dragonflies (and all insects) being exothermic, most of their body temperature control is achieved through exposure (or not) to the sun (some insects will shiver, too – you may see this in moths, for instance, on cooler nights).

It didn’t move, though, and I began to think maybe it was dead, the barbed feet still clinging to its final resting place. It did look a bit ratty, with a few nicks out of the delicate wings. It didn’t leave as I approached, or even as I reached out to grasp it. But as I gently folded the wings together over its back there was stiffness, resistance, that wouldn’t be there if the insect was dead. Holding the wings firmly, I lightly pulled on it to see if it would hold on to the screen; it did, and the legs moved feebly once detached.

So it was still alive, just sluggish from the cool night. I took a few photos but left it where it was. Half an hour later, presumably sufficiently warmed, it had left.

The large size of this dragonfly makes it a darner, and the dark body with two diagonal stripes on the thorax makes it a mosaic darner, one of the species in the genus Aeshna. There are more than a dozen mosaic darner species in our area, and they all look confusingly similar. Identification is usually best made with the critter up close or in the hand, but they rarely settle down for long and are frustratingly difficult to catch with a net, while in flight or otherwise. The vast majority of my identifications of this group have been made in situations such as this – sluggish individuals that are easy to get a photo of.

The ID for these guys depends primarily on two characteristics: the shape and colour of the thoracic stripes, and the same of the markings on the abdomen (particularly the segments closest to the body). The eyes can also be useful for species identification. Having the dragonfly in-hand, or having a photo of it, while you ponder the possibilities is really invaluable because it offers you the opportunity to check for small details.

In the case of this one, it has a very distinctive marking that no other species have: that little dot just on the inside of the front thoracic stripe. Also, the sharp hook on the front of the stripe itself. Both of these features identify it fairly easily as a Canada Darner, Aeshna canadensis. The majority of the mosaic darners are not nearly so easily identified, bearing more generic straight slines of varying widths.

I have two dragonfly guides: Stokes’ Beginner’s Guide to Dragonflies and Dragonflies Through Binoculars. I like the photos better in the first, but the species coverage and information are better in the second. There are a few other regional guides in print, some of which are very good, that I simply haven’t gotten around to picking up. At this point, though, I’m waiting for the new Peterson Field Guide to North American Dragonflies by Ed Lam. I’m not certain when it comes out, but Ed was contracted in 2006 with a four-year submission target (I think), which would make it within the next year or so. Ed is painting every single species. Males and females and colour morphs. I can’t even imagine the amount of patience such a task would require! But the guide looks to be beautiful and extremely usable once it’s done. You can check out samples of the illustrations at his website.

Canada Darners are late fliers. They first start to emerge in July, but they can be found on the wing through October, till we get into sustained periods of cold. Some species of darners are migrants, moving south in the fall to warmer regions. Those great swarms of darners you might sometimes encounter during the late summer and autumn might be migrant swarms, feeding before they push on (darners will also simply swarm where there’s really good eats to be had, though, and it can be hard to determine which type a particular swarm is). However, Canada Darners, as far as I know, are not one of the migrating species.

Interestingly, Dragonflies Through Binoculars notes that “this species darkens when cool”. I gather this isn’t the case with all species of mosaics, and would explain why this individual looked so muddy to me. Those thoracic stripes are usually sky blue and yellow-green. The abdominal markings are generally all blue. You can just see the colours starting to come out in the thoracic stripes – if that is indeed what’s happening here – though the abdominal markings remain brownish.

Aside from this guy, the only other dragonflies I’ve seen around in a couple of weeks have been meadowhawks, which seem to be the latest fliers around here, at least in any numbers. Soon, even they’ll pack it in for the year. It’s nice to enjoy these lingering traces of summer while they last.

Potter Wasp

It’s been very rainy here the last couple of days – since I finished and mailed off the moth guide, basically. As if the weather knew that I’d suddenly have lots of time for hiking about and enjoying the last of autumn. Since I haven’t been out (I’m very much a fair-weather hiker, or at least not a poor-weather hiker), here’s another photo I’ve had collecting dust on my hard drive for the last week or so.

I noticed this wasp on a short stalk of goldenrod as I was walking back from checking out the earth tongues. A wasp on a goldenrod is not in itself all that unusual. Wasps seem plentiful at this time of year, but they’re nearly all Polistes paper wasps. This wasp looked strange, and when I peered closer its pinched abdomen, with swollen, bulbous tip, was pretty obvious. I couldn’t recall having seen a wasp of this shape before (mud daubers also have very thin abdomens, but theirs are thinner for longer, and very distinct), so I took a photo and looked it up in my trusty Kaufman Guide to Insects when I came home.

As it nearly always does, the KGI had the answer. This was a potter wasp, most likely Eumenes fraternus, a widespread wasp of eastern North America. According to BugGuide.net, this species favours scrubby fields and forest edges, which is appropriate to the habitat I found it in, and can be found from mid-summer through fall at more northern latitudes like here. Adults feed on nectar, and are often found on flowers.

The name of the group, potter wasps, comes from their habit of sculpting their nests from mud. The cells of the nest are adorable little spherical creations with a flared opening that look like tiny clay jugs. These are provisioned with caterpillars or small sawflies, an egg is laid on the prey item, and then the chamber is sealed off until the new adult wasp is ready to emerge. Larval wasps will spend the winter in their pots.

Moths and ants

First, a note to say that The Moth and Me #13 is finally up at Today in NJ Birding History. Better late than never, as it’s got a great collection of moth-themed posts pulled together into one spot. Make sure you swing by to check out all the mothy goodness!

And second, I thought I’d take a break from work on the moth guide long enough to share a couple of recent insect sightings. The first, above, is actually a moth as well: a Hummingbird Clearwing, Hemaris thysbe. Dan was the first to discover these guys out in our garden, noticing them visiting the phlox in the evening. I’d been watching for them, but had yet to see any. I’ve even planted some Liatris, Blazing Star, expressly because I knew the clearwings liked to visit them during the day. I don’t know what I’d do without Dan to find all these neat things for me.

Dan caught one of the moths using my butterfly net and tucked it in the fridge to cool for photos. The top photo is of the moth after its photo session, still cool enough that it sat quietly on Dan’s finger. They were relatively unwary, as insects go, allowing for fairly close approach as they went about their business in the garden. My Liatris just has a couple of flower spikes, but we have wide swaths of phlox and it was to this latter plant that they seemed to primarily be coming.

Hummingbird Clearwings are not much smaller than their namesake garden birds, and from a distance quite resemble them as they hover at the flowers sipping nectar. They are day-flying moths, and can be encountered anytime during the daylight hours, though I find them to be more active in the evening. In the larger patches of phlox I find I often notice them first by sound, rather than by sight, as their wings beat so fast as to produce a loud buzz, more distinctive even, perhaps, than that of a hummingbird’s wings.

They are one of the most readily seen of the sphinx moths in our area, if only because the majority of the others fly at night. In a garden with appropriate nectar flowers – phlox, liatris, and bee balm are favourites – they’re not even that uncommonly seen, but if your garden lacks good plants, or if your surrounding area is missing the caterpillars’ host plant (hawthorn, honeysuckle and Prunus species such as cherries or plums), you might never see one. I was in university before I saw one, which surprises me a little, as there were certainly plenty of the host plants where I grew up, and my mom maintained a beautiful garden of perennials. Was I just not looking for them before that?

I really wish this photo had been in focus, but at least you can still see the moth. And in particular, you can see its long proboscis, curled as it flies from one flower to another. The proboscis is a hollow tube that the moth uses to suck up nectar, and in this species is nearly as long as its body. Often the length of the proboscis corresponds to the length of the flower tubes that the species prefers to visit, and indeed both phlox and bee balm are long-tubed flowers.

(This reminds me of the Darwin’s Comet Orchid, Angraecum sesquipedale, a Madagascar species with an incredibly long nectar spur that is only pollinated by a species of sphinx moth with an incredibly long proboscis – 12 inches long, in fact. I first saw this in a nature documentary on tv, but through the wonders of the intarwebs, you can watch the segment here on YouTube.)

On to other observations. A couple of days ago we made our last visit of the summer to our Blue Lakes MAPS site. It was quiet again – we suspect widespread breeding failure in our region, as the last few visits have been universally slow at all of our stations, a period when typically we’d be catching lots of young-of-the-year as they disperse from their natal territories. Even the woods were quiet, with very little bird activity, just the odd small flock here and there and hardly any late-summer birdsong. Given that birds were sparse we had to pass the time in other ways: reading a book, taking a nap, or, you know, looking at other things.

There were a handful of small saplings near the side of the path in one of the clearings that were absolutely covered in ants. After a couple of empty net checks I finally took my camera along to try to peer a bit closer.

The ants were only on these four or five trees, all of them Trembling Aspen (Populus tremuloides). They were congregated thickly along the thin twiggy trunks and side-branches, with very few bothering with the leaves. I had a feeling I knew what was going on, and sure enough, upon close inspection I could detect aphids on the bark where the ants were thickest. I blew a few of the ants off to try to get a photo of the aphids (below), but the ants were quick to move in to take their sisters’ places, so I had to be quick. It’s not the greatest of photos, as I just had my wide-angle lens with me and not my macro, but it’s sufficient for getting the idea, anyway.

I’m not sure what species of aphid this is, though Chaitophorus stevensis, a specialist on Trembling Aspen, is a possibility. Some aphids will pierce the soft bark of young twigs or stems, while others will target the thin membrane of leaves or leaf veins. These ones seemed to be of the former group. The ants are there as “farmers”, tending the “herds” of aphids and harvesting the sugary secretions of honeydew much the way humans maintain herds of Holstein cattle to collect their milk. The aphids benefit from having the ants around, too, as the ants stand around with their formic-acid shotguns and chase off any wolves or competing farmers from their herd.

Of course, the aphids aren’t entirely given a choice about their situation: in some ant-aphid relationships, the ants will actually bite the wings off the aphids to prevent them from leaving; in others, chemical secretions from the ant stunt the development of the aphids’ wings. The same chemicals on the ants’ feet that they use in laying communication trails for other ants are also used as a tranquilizer, keeping their aphid herds calm and subdued (though it could be argued that actually the aphids are simply recognizing which side their bread is buttered on and using the chemical trails as a boundary marker so they don’t inadvertently wander off too far).

That’s all for this week. Back to the grindstone!