bugs – Page 25

Today at Kingsford – Blister beetle

Right. So the purpose of yesterday’s post and all those headstones wasn’t actually to ramble on about life and death, but actually to introduce this guy, who I stumbled across in the grass and pine needles among the stones as I was slowly meandering through the cemetery. Its gleaming blue sheen caught my eye as it crawled through the obstacles. I knew what it was, so I coaxed it onto an oak leaf and gingerly moved it to the top of a stump where I could get better photos.

It’s a blister beetle, in the genus Meloe (oil beetles). There are 22 species in the genus, but they’re difficult to tell apart. All but one occur only in North America. Blister beetles get their name from their characteristic of exuding a skin-blistering chemical when they’re squeezed or unduly disturbed, a behaviour called “reflex bleeding”. The chemical, cantharidin, is contained in their haemolymph, or blood, and is exuded from pores at their joints. Members of the genus are generally quite plump, and flightless, though they have shortened, residual wing-covers.

You’d think that would be interesting enough, but even more so is that individuals go through multiple larval life stages (not just instars, but actual different types of larva), more than the average insect, which is called “hypermetamorphosis”. Eggs are laid on vegetation, and when the larvae, called triungulins at this stage, hatch they crawl up flower stems to wait on flowers for a passing bee. They hitch a ride on a female bee when she comes around, and are taken back to the burrow she’s created for her own eggs and larva(e). There, the triungulin moults into a grub and sits and consumes the pollen and nectar that the female bee brings to provision her own larva, and then eat the bee’s larva itself once it hatches from its egg. Each Meloe species generally targets a single species of bee, and while it will eat the larva, it can, if necessary, survive just on the pollen and nectar and so doesn’t qualify as a true parasitoid.

BugGuide.net also adds, “In at least one Meloe species, the larvae climb to the top of a grass or weed stalk as a group, clump together in the shape of a female solitary ground bee, exude a scent that is the same as, or closely resembles, the pheromones of the female bee, and wait for a male ground bee to come along. When he does, he tries to mate with the clump of larvae, whereupon they individually clamp onto his hairs. He then flies away, finds and mates with one or several real female bees, and the larvae transfer to the female(s).”

I presume this to be a female, both because she’s exceptionally plump, but also because her antennae are straight. Males have little hooks in the middle of their antennae which they use to grasp the female when mating.

Among other uses for the blister beetle – the males of some beetle species “collect” the cantharidin from the blister beetles and use it to impress females, and then includes the chemical in the sperm packet that’s transferred to the female. When she lays her eggs, they’re coated in the chemical, which protects them from predators. The chemical has also been used by humans for centuries in the production of the aphrodisiac “Spanish Fly”, frequently used nowadays as a date rape drug.

All legs

Readers who have followed my blog for a while may have noticed I haven’t posted anything on moths in a couple of months. Part of this has been that there’s just been so much else to catch my interest I haven’t gotten back to them. However, part of it was also that I broke my one and only mercury vapour bulb shortly after moving in to the new house. The mercury vapour is a very bright bulb that projects light in the ultraviolet spectrum and draws moths in like crazy. Nothing else really compares. I tried running my trap with just a blacklight in it, but didn’t catch very much. It has been a bit of a headache trying to replace the bulb from out in the middle of nowhere. The first set of bulbs I bought off eBay turned out to have the old-style mogul screw base used in security lights (rather than the standard, smaller one that all household bulbs today have), which of course didn’t fit my trap. It took me another few weeks to remedy that situation, and another purchase off eBay to get converter sockets that make a mogul bulb fit a household base (would you believe Home Depot and Rona don’t carry these?). But they arrived this Wednesday – hurrah! – and I’ve run my trap the past couple nights. We’re well past the peak moth period, which is June and July, but there are still lots of interesting species flying right now.

This morning, in a rush to get ready to go out for a training session for Elections Canada (I signed up to work at one of the polls during the election next Tuesday), I only had time to turn off the light and move the trap around the corner where it’d be out of the sun. So I wasn’t really looking at much, and if this guy had been anywhere else other than smack in the middle of the beige siding, I probably wouldn’t have noticed him. But there he was, presumably drawn in to the light during the night.

It’s a stick insect, of course, a Northern Walkingstick (Diapheromera femorata). Walkingsticks belong to the order Phasmatodea, which contains some 3000 species, most of which are tropical in range. In North America there are 33 species, all of which, except one, are wingless. The Northern Walkingstick is found through most of eastern North America, from southern Canada south to Florida, and as far west as Arizona and Alberta. It’s usually found in hardwood or mixed forests, so it’s no surprise to see it here, given that the region is nearly one continuous hardwood forest.

These guys are amazing insects. They’re not commonly seen; in my three decades I could probably count the number I’ve seen in the wild on one hand, but it’s been so long since I’ve seen one that I don’t know how many digits I’d be able to put up. So I was doubly excited to find it, both for its cool factor and its apparent rarity (it’s not actually all that uncommon, but appears rare because one rarely sees one).

Many insects have evolved body structures that camouflage them, but the walkingsticks and stick insects have taken it to an extreme. Their bodies are thinner than pencil-thin, and the joints resemble the bumps on a twig. Their legs are tiny and delicate, and extremely long. While their body is brown, their legs are green, kind of like the leaf petioles or young sapling twigs that stem off a main twig. When at rest they often align their forelegs, and sometimes their back legs, straight out in line with their body as in the first photo, to increase their disguise. A few tropical species look like walking leaves, rather than twigs.

Although stick insects, like all insects, go through metamorphosis, theirs is a “simple” metamorphosis, where the larval and pupal stages have been dropped. Baby walkingsticks hatch from their eggs resembling miniature adults, only green, and simply grow bigger as they age by shedding their skin, eventually becoming brown. Grown adults are sexually dimorphic, with males being considerably smaller than females – males may reach 7.5 cm (3 inches), while females can grow to 9.5 cm (3.75 inches). Females have a more swollen look than males, and I suspect the twigginess of this individual makes it a male, but the pincers at the end of the abdomen confirm it (they’re used in mating).

Females of this species will lay their eggs in the leaf litter of the forest floor (BugGuide.net says they “drop eggs singly”.) In the spring these eggs hatch and the nymphs reach sexual maturity by late summer or early fall. There are a few species of walking stick that reproduce through parthenogenesis – that is, there are no males, and the females essentially lay eggs that are clones of themselves. Even more amazing, walkingsticks are often able to regenerate lost limbs during larval stages, something most insects are incapable of doing.

The walkingstick’s face looks much like just another knob on the end of the twig. Their entire body design is built around blending in with their surroundings. They feed primarily on the deciduous leaves of hardwood trees, particularly oak and hazelnut, also rose and apple. Nymphs apparently have a different dietary preference, favouring sassafras, raspberry, and black cherry. In years of high walkingstick abundance they have the ability to severely defoliate their food trees. Their simple dietary requirements make them an easy bug to keep and breed in captivity, where they may live to about a year old.

After posing the insect on a number of branches and trunks where he was easily seen, I placed him in the foliage of an aster, now nearly done blooming. This is where his camouflage really kicked in, and he all but disappeared into the plant. Walkingsticks are generally slow movers (as are the twigs they mimic), though they can really boot it when they want to (as I discovered while trying to move him from one spot to another). They sometimes sway gently as they move, hypothesized to either mimic swaying branches, or possibly aiding in their visual detection of their surroundings by differentiating close objects from the background (something characteristic of simple insects).

I left him resting in the aster, where he was well-hidden. Hopefully they’ll be a frequent sight around here! It does make me think back to a few small, thin, green little bugs that we had hanging around the house back in August and didn’t know what they were. I wonder if they could have been young walkingsticks?

The gentle giant

I’ve been holding on to this subject for a little while, always having something else lined up or that I came across that I ended up talking about first, but I’ve been wanting to post it. Yesterday and today we had guests up, so I didn’t get a chance to take many other photos, which meant this was a great opportunity to sneak this one in.

Not long after our arrival here we started noticing these GIANT, MONSTEROUS wasps coming to the porch lights at night. So large, in fact, that wasp wasn’t the first insect that came to mind when we looked at them. It took me actually catching one, and chilling it in the fridge, to get a good look at it and confirm that it was, indeed, a wasp. A little nervous to even put my hand anywhere near the thing, I was very careful to take my photos quickly, while it was still sluggish from the fridge, and using a pencil for scale rather than my fingers like I often do.

My first thought was a cicada killer, a type of native wasp that is similarly giant. But the markings weren’t right for cicada killer (and I looked at quite a few pictures, feeling at a loss for whatever else it might be). Eventually it took doing a search on BugGuide.net for “giant wasp”. That turned up a good number of hits; cicada killers, of course, but also my wasp. Turned out, it’s a European Hornet (Vespa crabro), the largest species of the hornet family, and an introduced species, originally native to Eurasia. It was introduced to New York sometime around 1840, and has become well established in woodlands and forests through much of the east.

Fortunately, these hornets are a fairly peaceful species. Sure, they sting, as do all hornets, but it requires some specific provocation, they aren’t aggressive simply to one’s presence. This proved true as we would go out to check out the moths and other insects coming to the lights, none of the hornets ever seemed even the least bit interested in us, although their heavy, loud buzz was still a little off-putting. The hornets are attracted to artificial light on summer evenings, not unlike many species of ichnumonid wasps and sometimes other types of wasps as well. BugGuide.net suggests they may be seeking prey, but the ones I observed didn’t seem to show much interest in the other critters at the light.

The nests the wasps build is a one-time-use-only structure. They nest in hollow trees, or sometimes in attics, which are a decent approximation of a hollow tree if the real thing is not abundant. Like the yellowjackets, another type of hornet, they build paper nests, which reach peak size toward mid-September. They can attain quite a large size by the fall. The queen in the nest then lays special eggs that develop into the reproductives – the new queens and males – which engage in a nuptual flight. The old queen, and the males once they’ve mated, all die, but the new queens find nooks and crannies in which to hibernate for the winter.

In the spring, the new queens emerge and find a suitable spot for a new nest, and get started on building the paper cells. She lays a few eggs in these cells, and provisions the larvae with insects herself. Eventually they mature into sterile female workers, who then take over the duties of building the nest and caring for the larvae, while the queen goes about laying more eggs.

While the larvae are fed insects, the adults feed on nectar and sap, which is high in sugar, providing energy for powering flight. In addition to this, the larvae are able to secrete a sugary liquid, which the workers also use to supplement their food.

Like most insects, the adults have large, compound eyes, and three ocelli on the top of their head. The compound eyes are primarily used for detecting movement and discerning shapes that are useful in navigating and finding nectar sources. The ocelli are primitive eyes that are only really useful for detecting light and dark (something the compound eyes aren’t good at), which helps the wasps stay upright relative to the ground, and also helps in determining day length, etc. It may be that the insects use one or the other of their two sets of eyes to navigate by the sun, and the artificial lights at night confuse this sense.

You can also see well here the large, powerful jaws that the adult uses for catching and dissecting its prey. They’re not used for eating, since the adults don’t eat solid food themselves, but rather for handing the insects that are taken back for the larvae to feed on.

I love close-ups of insect feet. Wasp and hornet feet (as well as many other insects) are neat because they’ve got little spurs at each of the joint, and two long claws at the tips of the foot. It’s these claws that allow them to climb up vertical surfaces, or even to hang from the ceiling, finding little imperfections in the surface that we can’t detect.

The wasp I caught takes a moment to clean her back legs by rubbing one along the length of the other. Her stinger is usually kept retracted unless she’s planning on using it, so it’s not visible here. Given their size, one would expect the sting of this species to hurt like an expletive, but it’s less painful than bee stings. This is because the stinger of the bee is pulled from the abdomen and continues pumping venom into the victim beyond the initial attack, while wasps, since they need to be able to use their stinger repeatedly when collecting prey insects, only inject a relatively small amount. Blackburnian got stung by one when he was trying to remove it to outside (he made the mistake of swatting it), and it barely swelled up or got sore. Their threatening appearance and old wives’ tales regarding the potency of their sting have resulted in the species being persecuted through much of its native range, however, and there are regions within Europe where the hornet is now endangered.

She’s presumably one of the sterile female workers, as the new queens wouldn’t be flying yet by then. Even with the ordeal of being captured, stuffed in a fridge overnight, and then asked to pose for the camera, she was very well-behaved. The only time she showed any reaction was when I pushed the pencil tip up next to her. Even then, she reared back with her front two legs in the air, paused for a moment to assess the threat, then, deciding it was benign, continued walking along the deck railing. Sure are fearsome looking critters, but really they’re just gentle giants.

Today at Kingsford

My mom was up today and as part of her visit we made the obligate trip down to the lake. My trips to the water have been more sporadic lately as the weather cools, particularly during rainy periods, which it has been lately. The few trips I have made have been to the boat, and then across the lake. So I hadn’t been paying too much attention to the vegetation and goings-on in the immediate vicinity of the dock.

My mom pointed out some leaves, fallen from the huge tree on the shore, which had a gall at the base of the stem. I believe the tree is an Eastern Cottonwood, towering probably close to 100 feet, with a thick trunk several feet around. The galls, after looking them up, I believe are the result of the Poplar Petiolegall Aphid (Pemphigus populitransversus).

This aphid has a complicated, two-part life cycle. The first stage starts with the female aphid, sometime just as the leaves are beginning to grow, burrowing into the leaf petiole (the stem), right at the base of the leaf itself. This intrusion causes the tree to form a gall around the wound in an effort to contain the attacker. The gall is hollow, and inside she lays eggs which have developed into winged adults by summer.

Around July here in Ontario, these new adults leave the galls and fly out in search of plants in the Brassicaceae family, which includes commercial vegetables such as cabbage, cauliflower, beets, turnip, radish, and others. These adults burrow into the soil and feed on the roots of the plants, but only cause serious commercial problems when the vegetables are planted late such that the roots are young when the aphids discover them (thereby stunting the growth). Well-developed plants are not bothered much. They reproduce parthenogenically – meaning the females create clones of themselves without mating.

The aphids spend the winter buried up to 20 cm (8 inches) deep (according to two sources; one says they return to the tree to lay eggs). Winged adults are produced either in late autumn or in the spring (it’s not clear with the two sources, but the one that has them returning to the tree in the fall obviously requires winged adults in the fall), which return in spring (or the fall, in the case of that one source) to the poplars and lay eggs in the crevices of the bark. These eggs grow into more reproducing individuals, but in this case the female lays only a single egg on the stem of a leaf, which becomes the aphid that burrows into the petiole and starts the cycle all over again.

Something like that, anyway. It seems that the life cycle of this species is still a little fuzzy. These aphids inside the galls seem out of place based on what I’ve read. Are they just late summer aphids that never made the trip to their winter roots? Or that got started late and plan to head out soon? There were some winged individuals in the galls. Or do some spend the winter in the leaf gall instead of the soil? Maybe some adults return there? The gall, rather than having an open hole, had a sort of cap formed from a folding-over of the petiole, that would keep it snug. My web sources don’t say, so perhaps it will remain a mystery.

Buried seashells

This afternoon, Blackburnian suggested we take Raven across the lake to the park and do some exploratory hiking. I thought this was a great idea, so we bundled Raven into her harness, hiked down to the boat (now no longer docked at the dock because the water level has gone down so much from dam control that the dock is surrounded by mud), and boated across to the park.

We had a great hike. Surprisingly, this is the first time I’ve gone over and hiked around myself, though Blackburnian’s been there a few times. For whatever reason, I’d just never made it, other things had come up. So it was nice to see a bit of the park interior. I’ll elaborate more on the hike tomorrow.

One of the things we came across while hiking, though, was this underground paper wasp nest. Aside from the fact that it was a wasp nest built of paper underground, we really had no idea what it was. So I snapped a few photos, with the intention of looking it up when we got home. The wasps were totally unconcerned with us being there, and me nosing up to the mouth of the burrow it was set in so that I could take photos. They just went about their business, popping inside the entryways in the paper, one or two flying away while I squatted there.

I was surprised to find, when I got home, that this was the nest of Eastern Yellowjackets (Vespula maculifrons). I don’t know that I’ve ever consciously looked at a yellowjacket and thought, “that’s a yellowjacket,” so I’m not sure what I was expecting. Something more yellow, maybe. I knew yellowjackets primarily nest underground, but for some reason this didn’t twig with me. Plus, yellowjackets have a ferocious reputation, and here these were, apparently unconcerned. Nevertheless, the wasps in this burrow were Vespula.

Yellowjackets as a group build paper nests using wood and plant fibers mixed with saliva. They can make some beautiful patterns in the paper they create, scalloped sea-shells of grays and whites. They’re a social species, like many of the Hymenoptera, with a single reproductive queen cared for by many female worker offspring. Although the larvae are fed bits of chewed-up insects, the adults themselves feed on nectar from flowers. They’re also not opposed to visiting sugary drinks, and are probably the wasps most commonly seen crawling into pop cans.

The colonies never survive the winter, despite being nestled underground. In the fall, male drones and young queens are produced from the colony, and these then fly away to mate. In the photo above you can see three workers, the slightly smaller ones with more yellow, and one male, the slightly larger one with more black, on the left. The new queens will mate with the males; the males will then die, while the queens find a safe place to hole up for the winter. They are the only ones to survive. Come spring, they find themselves an abandoned burrow, and start up a new colony. They begin from scratch, and the first brood is completely cared for by only the queen. Once she’s raised a few workers, she settles in to her role as egg-layer, and her daughters run the nest. By the end of the summer the nest may hold up to 5,000 individuals.

Interestingly, all workers are females because they are diploid – having two sets of chromosomes. Males are created through the laying of unfertilized eggs (the queen, who holds the sperm from her mating the previous fall in a storage chamber in her abdomen and doles it out according to the gender of offspring needed), and are therefore haploid – have just one set of chromosomes. New queens are diploid females that are fed a special concoction (in honeybees, called “royal jelly”) that promotes her development into a reproductive individual.

I gather the workers will sting if provoked, and their sting can be acutely painful. However, probably just walking by won’t provoke them. On the other hand, the juicy, tender larvae are a favourite delicacy of bears, skunks and others, who will endure the workers’ stings for the treat. As long as you’re not digging in to the nest for a snack you’re probably fine.