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!

Yesterday while taking the puppy out for her hourly bathroom break, I happened to notice a few swarms of insects crawling among the grass on the lawn. Closer inspection revealed them to be ants. They were reasonably contained to a small area, perhaps a foot square, for each swarm, and there were at least three or four that I noticed. They seemed to be mixed individuals, half small yellow-orange ones, and half larger reddish ones with wings. Sprinkled among them were a number of small black ones with wings.

It was the makings of a reproductive flight, and the participants are most likely of the genus Acanthomyops*. Late in the summer, on a warm, humid day, often just after a rain, these ant colonies send forth their reproductive individuals to fly, mate, and establish new colonies. The little yellow individuals are workers. They won’t be going anywhere; once all the excitement is over they’ll return to the nest and get back to business. The larger ones, though, with the big clear wings, are the new queens, and the little winged black guys are the males.

*Myrmecos comments to suggest the ants are Lasius claviger, which used to be Acanthomyops but scientific evidence showed that the species actually belonged to the closely related sister species Lasius.

They have evolved this strategy of all swarming at once for two primary reasons. The first is that if everyone comes out at once it makes it a heck of a lot easier to find a mate. Just within our little lawn there were several colonies producing reproductives that afternoon. The other reason is the whole safety in numbers premise – if everyone comes out at once, it’s impossible for predators to get everyone, so some individuals will survive to start a new colony. These swarms are sure an impressive and intriguing sight, it’s easy to sit for a while and watch them all crawling up and around and over.

Curiously, when I was looking up on BugGuide.net for more info on the genus (they don’t offer much, unfortunately), I discovered this photo of the same sort of Acanthomyops ant swarm, which was also taken yesterday. The photo was from Connecticut, which presumably had shared similar weather patterns to us here. I wonder just how many colonies were swarming yesterday afternoon?

The common name for ants of this genus is Citronella Ants, for the smell they emit when disturbed or crushed. I didn’t know this when I was looking for them, so didn’t check, but wasn’t likely to stick my hand in there anyway. They don’t have the formic acid defense that the most common household ants we encounter do, but I didn’t know that at the time. Another name they’re known by is Foundation Ants, for their habit of nesting in the loose soil that frequently surrounds the foundation of suburban houses. Unlike carpenter ants, however, they are harmless and don’t do any damage to the house, nor do they tend to forage inside.

The queens head for tall objects sticking up from the ground, such as twigs or blades of grass, from which they take off on their flight in search of a mate. Once they’ve found a male and mated, they’ll drop to the ground and look for a suitable, uninhabited location to start a new nest. The soft soil around foundations is easy for the young queens to dig in, which is why it’s so often favoured. Once the queen finds a spot she’ll drop her wings and start excavating her new home. It’s a lot of work, and will take her a while to establish. Many nests never make it past this stage.

Some species of ant, including Acanthomyops latipes (I don’t know if these are that species, or a different species of Acanthomyops), will avoid having to go through all that work by instead searching out a colony of the closely related genus Lasius. She’ll invade the colony, kill the Lasius queen, and take over control of the existing workers while she breeds a new colony of her own offspring. This behaviour is called temporary social parasitism. In fact, because of this close relationship between these two genera (as well as other reasons), Acanthomyops is sometimes considered a subgenus of Lasius, rather than a separate genus in its own right.

This little male looks tiny next to the large queens. The males, unlike the queens, will retain their wings till death, but that’s not all that far away. The male’s sole purpose appears simply to mate with new queens, after which he dies. While queens may be produced by young colonies, males are apparently only produced from older, mature colonies. A colony may last for many, many years, depending on the species. A queen will live for several years herself (up to 15 years depending on the species), but for older colonies it may not be the original queen present; rather, she may have died and been replaced by a daughter.

Not sure what this worker is doing. In fact, I’m not sure why the workers were out amid the swarm of winged reproductives period. I didn’t spend a lot of time watching them, because I had a rambunctious puppy at the end of the leash who didn’t have the same appreciation for such phenomena. I put her in her crate so I could take a number of photos of the colony, but couldn’t leave her there long. When I returned to the area this afternoon they were all gone, the area was empty. It’s amazing how fleeting it is, and you really need to be in the right place at the right time to notice it. Presumably a number of those queens I saw yesterday are now off starting a new nest of their own.

Tag: ants

Moths and ants

Flight of the queens