Moths and ants

Hummingbird Clearwing, Hemaris thysbe

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.

Hummingbird Clearwing, Hemaris thysbe

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.

Hummingbird Clearwing, Hemaris thysbe

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?

Hummingbird Clearwing, Hemaris thysbe

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.)

Ants with aphids

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.

Ants with aphids

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.

Ants with aphids

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!

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5 responses to “Moths and ants

  1. For those who can’t pronounce or spell “proboscis”, the word “trunk” might do in a pinch. ;)

  2. I have never heard of this ant-aphid relationship. Thanks for bringing this mutualism to my attention!

  3. The pictures of ants makes me itch……

  4. Pingback: Canadian Sphinx | Seabrooke Leckie

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