bugs – Page 27

Black and orange but green all over

A couple weeks ago I discovered this bug crawling among my herb planter on the deck. Although it wasn’t large, about the size of your index fingernail, it was vibrantly coloured, and really rather hard to miss. I recognized it as being a bug. That is, a true bug, a member of the order Hemiptera, rather than a bug in the colloquial sense of the word (though it is also that, of course). The dual use of the word can cause some confusion, and is the reason that the word “true” generally prefaces “bug” when speaking in a specific sense.

The Hemiptera include a wide variety of insects, from cicadas to leafhoppers to shield bugs and others. The group is defined by the presence of a long stiff “beak” or proboscis, which is really the mouthparts and mandibles of other insects evolved and modified into a long tube. They use this beak to pierce plants for food, usually sap. Also, the name Hemiptera reflects their special wing structure – “hemi” means half, and “pteron” means wing. Rather than the familiar membranous wings of most insects, the basal half of Hemipteran wings is opaque and hardened.

I also knew that it was probably a shield bug, based on its shape (which also gives the group, the family Pentatomidae, its common name). The shield bugs are also known as stink bugs because they possess glands on the underside of their middle segments that, when disturbed, are capable of releasing a pungent liquid that contains cyanide compounds. Fortunately, I didn’t have the opportunity to experience it firsthand, as none of the bugs I encountered did this. Interestingly, the bright colours of the nymph are suggestive of aposematic colouration, and I wonder if it’s a reflection of these cyanide compounds.

However, I was confused when it came to species. I couldn’t spot anything that quite matched in my guide, and when I looked closely at the bug, the apparent lack of wings seemed odd. It seemed like it had a raised button right in the middle of its back. I saw a few more, here walking around the rim of my water fountain, others among the blackberry canes in front of the house; it seemed reasonably common, at least here.

Some poking around on BugGuide.net eventually revealed them to be nymphs, which is why I wasn’t sure what they were, and why they didn’t appear to have wings. I discovered this mangled mess hanging off a leaf of my sunflower plant yesterday. I believe it’s the cast-off skin of one of my mystery bugs.

The species is the Green Stink Bug, usually labeled Acrosternum hilare. Based on the BugGuide.net page, the bright nymphs seem to be in their 5th instar (larval stage), which is the final one. In each larval stage they change colour and pattern just slightly. Some will become nearly green in their final instar, while others will remain these bright colours.

Yesterday evening I ran my moth lights, and found these guys who had come in to the sheet. It’s the adult form of the species, and is larger than the nymph, maybe the size of my thumbnail. I hadn’t seen any even just the night prior, so perhaps one of the ones at the sheet is the owner of the shed skin hanging from my sunflower. They’re dramatically different than the larval form, and although the species is depicted in the Kaufman guide to insects, the nymph isn’t, so I didn’t recognize it. Kaufman does an admiral job with the guide, but there’s still only so much one can reasonably depict in a single guide to insects.

The Green Stink Bug is a common bug through much of North America. It feeds on a wide variety of plants, and is found in a range of habitats, throughout most of the year. Here in the north they just have one brood, but in southern, warmer areas they can have two. These nymphs and adults probably belonged to our one hatch here. Their eggs are attached to the underside of a leaf in two rows, and are often described as “keg-shaped”.

Incidentally, in the above photo you’re able to see the “half-wings”, with the lower half of the front wings looking like it’s protruding from a cover like a beetle’s elytra (really, the “cover” here is the upper half of the front wing). The wings are termed hemelytra for their resemblence to the true elytra of beetles.

There’s a second species in the south that looks very similar to this, but has red-striped antennae instead of black. Both can be significant agricultural nuisances given their wide range of food preferences. Often they’ll develop a taste for seeds, and will target growing crops such as corn, soybeans, beans, peas, tomatoes and others, before the veggies are yet ripe (doesn’t go over well with farmers, understandably). When they’re not aggravating crop farmers, they’re off tormenting orchard growers, as they’ll happily feed on the stems and foliage of other plants, particularly apple, cherry, orange and peach trees. They are one of the guilty culprits responsible for “catfacing” on fruit such as peaches and tomatoes.

They’re a particularly hardy bug and don’t respond to pesticides. However, they use a particular pheromone to communicate that can be artificially produced and used to draw adults away from crop areas. They’re also parasitized by a tachinid fly, but that would be a bit harder to ensure it worked.

It’s interesting to get to see the life cycle of something like that (even if I did miss out on the egg and early stages). All too often we get a fleeting glimpse of the insect, usually in its adult form, and are left to wonder about the rest of its life history. Ruth over at Body, Soul and Spirit has a really cool video of a monarch caterpillar shucking its skin and turning into the pupa that precedes the chrysalis, which I highly recommend checking out! It took me over half an hour to download on my dial-up connection, but was very much worth the wait once it was completely loaded and I got to watch it.

Get out and look!

Back in the fall I spent many nights at Tommy Thompson Park in Toronto with a sheet and blacklight, looking for moths. I caught many, all, of course, new for me, since I was just getting into moths and wasn’t familiar with anything yet. But I also caught a few less common species, and some notable things. The above moth is a Small Mocis, Mocis latipes, a very rare vagrant up from the States into Ontario. I gather there’s just a handful of records for the species in the province. And I got two that season!

So why do I mention this now, in August?

Shy Cosmet, photo taken by Susannah at Wanderin’ Weeta

A couple days ago I got a note from Susannah over at Wanderin’ Weeta (With Waterfowl And Weeds) that she’s finally got some results from an experiment she’d begun back in the winter. She had read my post back in the winter about the cattail caterpillar, the lavae of a moth that makes cattail heads go all fluffy during the winter. She had also noticed fluffy cattail heads where she lives in the Lower Fraser Valley of BC, and decided to investigate. All online resources indicated that the Shy Cosmet, the moth whose larvae I found in my cattail heads, did not occur as far west as BC, so when she found caterpillars in her cattail heads, she contained them so she could see what they turned into. The answer? Shy Cosmets. The species was not listed on the recently-revised 2008 version of the checklist of lepidoptera (moths and butterflies) of BC, and folks at E-Fauna BC are checking in with the experts to see if there are any other known records for the species there. It’s quite possible that Susannah has the first documented record for the province!

Undescribed wasp sp., photo taken by Julie at Bootstrap Analysis

Then today, Julie at Bootstrap Analysis made a post about some wasps she found in her yard. Back in the fall she started a personal project to document all the wasps, bees and flies that she found in her yard – not all that different from someone who keeps a list of the birds or the butterflies that visit their garden (and I’m sure Julie does that, too). Aside from discovering some wild-looking species using her yard, she also found a new state record that fall in the grass-carrying wasp Isodontia elegans. Also last fall she found the above wasp which, when she couldn’t identify it, she posted to BugGuide.net for help. It turned out it was a relatively new species to science – it hadn’t even been described yet (all species have a formal “description” that is published wherein they’re given a scientific name and the details of the species that differentiate it from others are laid out, as well as other known characteristics and behaviour). The species was identified on BugGuide.net by a professor at the University of Guelph (my alma mater!) as a new one he was collecting data on, and will be formally described by him in the near future.

September 7 has been designated as International Rock-flipping Day. The event was inaugurated last year by Dave at Via Negativa, and went so well they’re doing it again. Dave and co-coordinator Bev of Burning Silo encourage everyone to go out on Sept 7 and flip a rock or two (or three or four if you’re having fun. Record and/or photograph what you find and send the results to Dave and Bev, whereupon they’ll gather everyone’s responses into a single spot and send it out to participants. You can post the results to your blog, put them up on your Flickr or other photo account, or, if you don’t have an online presence, simply send them off to Bev who’ll put them up on her site. Beyond just being a lot of fun, the project also has the potential to contribute to science by documenting species in places they haven’t been seen before, or behaviours that haven’t been observed, or other valuable information. More details at the official IRFD page.

So what’s the point of this whole post? That no matter what your expertise, no matter where you are, where you live, whether you have acres of land, a little backyard, or a balcony, you can still make valuable observations. It’s likely that all the big vertebrates have been recorded for your area, but there are thousands of invertebrates that are often overlooked because of their size and habits, plants that blend in to the rest of the foliage, and behaviours of animals large and small that are always interesting to observe and important to document. The one key ingredient to having success and finding things, though? You have to get out there and look! Isaac Newton was probably the only person to have science come to him…

Arrival of the dog-days

I’ve noticed a couple of these old, empty husks clinging to vegetation at our new home over the last week. They’re the empty exoskeletons of cicadas that have metamorphosed into adults. Cicadas are somewhat grotesque, as bugs go, with large eyeballs set wide on a broad head, a thick thorax and abdomen, and large, clear wings with strong veination. These larval exoskeletons are even more so. Despite their appearance, however, cicadas are harmless to humans, and they have no interest in crops so aren’t considered a commercial pest, either.

Mostly they’re just loud. They’re the insects that make the long, sustained buzz that we tend to associate with the hot, dry, and sunny days at the height of summer. When you’re close to the cicada while it’s making this noise the sound can be as much as 120 dB – that’s louder than a jackhammer! Only the males make the noise. Most insects, like crickets, make noise by rubbing two body parts together, often the hind legs or wings. Cicadas are different in that they use a built-in mechanism to make noise. They have a set of tympanic membranes on the sides of their abdomens called “tymbals”. The tymbals have muscles that connect to their inner surface that pull the membrane inwards when they contract. This produces a clicking sound. As the muscle is relaxed and the membrane returns to its normal position, another click is heard. By doing this extremely fast and many times over, the cicada produces the buzz we associate with them. The male’s abdomen is also mostly hollow, which acts as a resonating chamber to increase the volume of the sound. Cicadas “hear” through a membrane mechanism much like a frog’s ears, which could be damaged by the loud noise he makes with his abdominal tymbals, so the male “turns them off” while he’s calling.

There are two types of cicadas. The most famous are the periodical cicadas, the ones that are on 17- or 13-year cycles and come out en masse in huge swarms in a single summer. This strategy developed to make it difficult for a predator to specialize on the adults of the species; since both 13 and 17 are prime numbers, a predator specialist would also have to be on a 13 or 17 year cycle (if the cicadas were on a 15-year cycle, for instance, a 5-year cycle predator could sync up with them easily).

The other cicada species have much shorter life cycles, usually between two and five years, and adults are present every year, giving them the name annual cicadas. Despite that I would have to have lived through at least one periodical cicada emergence, I’ve never observed it firsthand. Annual ciciadas, on the other hand, I’ve observed regularly. As I was returning to the house from the dock this morning I happened to come across this one, still in larval stage, climbing up the side of a tarp.

He looked like he’d come straight out of the sand. Cicadas spend virtually all of their lives underground. The adult females lay their eggs in the twigs and branches of trees, and the larvae, once they hatch, drop to the ground and burrow into the soil. They feed on the sap from the roots of the trees. Their front legs are broad and strong, adapted for digging, with well-developed hooks on the ends.

After several years the larval cicada finally reaches a size where it’s ready to metamorphose. It climbs out of the dirt and up onto a plant or the trunk of a tree. In the case of the cicada I found, it had decided the tarp provided a suitable substrate. The cicada sets its hooked feet firmly, then splits open the skin on the back of the head and thorax and pushes its way out. Cicadas undergo incomplete metamorphosis, meaning that they don’t have a pupal stage the way butterflies and many other insects do. Instead, they go directly from their final larval stage to the adult, crawling out of their skin in their final adult form. It comes out pale; as the insect’s exoskeleton hardens, it will darken. The adult will eventually be olive green and black.

I figured that this one was looking to find a spot to metamorphose, and I was right. I sat down and watched most of the insect’s emergence. When it was mostly out it sat and recovered some energy for a while. It stayed in that position for at least 15 minutes; when I eventually decided that it wasn’t going to be doing anything imminently I went inside to get lunch started, as Blackburnian and I had plans to go out this afternoon. I check on it once while waiting for one side of a grilled cheese sandwich to brown, and it hadn’t moved. However, in the space of time it took to butter another sandwich and put it in the frying pan, the cicada had emerged completely and unfurled its wings.

It was an interesting process to watch, because I could see the insect, while still in its larval skin, shifting to make sure its claws were firmly dug into the substrate, and then appearing to apply pressure to its back to split the skin. Once it was starting to emerge I could see it working to pump haemolymph, the insect’s equivalent to blood, into the soft wings and body parts. It would have been neat to capture some of it on video, or to take a time-lapse series of the process.

However, I did my best to get a series of photos of the emergence of the cicada, start to finish. Photos below of the process. You can see in a few of them the long, tube-like piercer the insect uses to suck sap from trees. I believe this is a Dog-day Cicada, Tibicen canicularis.

And all that’s left is the empty shell.

So I guess if the Dog-day Cicadas are emerging, that means the dog days of summer must be officially arrived.

Construction workers

My parents’ house is an old century farmhouse, onto which a three-room addition was built. Two rooms are on the same level, but the one at the back is slightly raised, and the roof is at a shallower pitch. Where the two meet there’s a slight overhang, which has been edged with the same trim that runs along the front of the house. For the last few weeks, there have been small piles of sawdust collecting on the shingles under the eaves of the house here. In rainstorms they all get washed away, but in short time they have returned.

There are actually termites in Ontario, and they have been reported from Halton County where my parents currently reside. However, termites tend to be subterranean creatures, building tunnels on the surface of objects (such as walls) when they want to move someplace. While termites might be the creature that immediately jumps to mind at seeing such evidence, sawdust observed so high off the ground and without any apparent tunnels most likely belong to another culprit.

I climbed up onto the roof while I was painting that bit of the exterior wall, and got a second clue. From the bit of trim above the sawdust piles, I could hear very distinct, very loud chewing. Because of the way the roof slopes I could look up and under the eaves and see if I could spot whatever it was, expecting a vertebrate of some sort, but nothing was there. Annoyingly, while I was trying to check things out, and then later as I was painting, a bumblebee kept coming up and hovering around me. I’d back off and let him disappear and then continue on.

I overlooked the most important clue: the bumblebee. Which, it turned out, was not a bumblebee at all. I came home and looked up bumblebees. They are all generally solitary insects, nesting underground. I had this vague notion of “carpenter bee”; I knew carpenter ants, carpenter beetles… I googled Carpenter Bee anyway. The very first webpage that came up, an information page at Penn State, started out by saying, “People who complain about bumblebees flying about under the eaves of their homes are probably being annoyed by carpenter bees.”

Well. Mystery solved. Here in eastern North America, the species we have are Eastern Carpenter Bees, Xylocopa virginica. They are large, chunky, bumblebee-sized bees that are also marked in black and yellow fuzz. The primary visual difference is that bumblebees always have fuzzy abdomens with a bit of yellow, while carpenter bees have completely black, fuzz-less abdomens. Of course, I didn’t know this at the time. I also think I had at some point learned that bumblebees nested underground, but was forgetting that at the time. Bumblebees will generally have no interest whatsoever with your eaves.

Carpenter bees, on the other hand, are very fond of eaves. Or really, dead, unpainted wood in general. Carpenter bees, as the name implies, will construct their nest burrows in dead wood. In the wild they would ordinarily do this in snags, dead branches or fallen logs, on the underside or the lee side of the wood. However, they’re not especially picky about the wood they use, and the processed wood we humans use to build our homes and outbuildings, as well as fence posts and boards and other outdoor constructions, will suit them just fine. If you want to make sure the bees don’t target your buildings, make sure they’re all varnished or painted, which generally discourages them.

Females do all the nest-building. The individual in the photo above is a female; she can be told by her longer, pointy abdomen and her all-black face (males have a splash of yellow across their forehead). Females also have larger heads with more widely-spaced compound eyes (those of a male come close to touching at the top). Females use their powerful mandibles to carve out the tunnels. She looks like she might be holding a wood chip from her tunnel in the photo above.

They start out with a hole approximately 1 cm (less than half an inch) wide, building straight in to the wood for an inch or so, usually against the grain, and then make a right turn and build the rest out perpendicular to the entry tunnel, this time with the grain. They generally prefer wood that’s at least two inches thick, so the 1×8 boards that formed the trim on the eaves didn’t actually present a very thick tunneling substrate.

The tunnel will end up being 4 to 6 inches (10-15 cm) long when completed, and it takes a female on average about 6 days to complete an inch of tunnel, which means anywhere from 30 to 42 days to do the whole thing. She pretty much spends her whole life focused on that activity, and when she’s done and has laid her eggs, she’ll die.

Once the tunnel is complete, she’ll systematically start filling it with future bees. She’ll begin by forming a ball of pollen and regurgitated nectar and placing it at the end of the tunnel. She’ll lay an egg on the ball, then seal it off into its own compartment using chewed wood pulp to form the barrier (perhaps that’s what she’s carrying that woodchip for in the photo). She’ll form 6 to 8 compartments within the tunnel, each with a single egg. This is a lot of work for just 8 offspring, not all of which will survive to adulthood and reproduction age.

Carpenter bees are not truly social bees, the way honeybees are; every female has the potential to reproduce, and there’s no queen organizing the group. Each female will build her own tunnel. However, they will often congregate in the same general area. This is partially because a female will tend to reuse the nest she hatched from, or build her new nest nearby. A single board can be targeted and eventually become riddled with nests while other boards may be left untouched. In cases where these holes are excavated in a structural beam they may cause concern, but generally speaking carpenter bee damage is mostly cosmetic.

From the laying of the egg to the emerging of the adult takes about seven weeks, though the timeframe may be longer or shorter depending on local temperatures through that period. The adult will emerge from the chamber where it developed by chewing its way out through the partitions along the long tunnel to the entrance. Adults will generally emerge in mid- to late-August, and will spend the rest of the summer and fall feeding on nectar from flowers (an interesting habit they have is to not always go through the mouth of the flower, but instead sometimes pierce the base of the flower to get at the nectar without pollinating it).

In the fall they’ll return to the tunnel where they hatched from, and they’ll spend the winter there. In the spring they’ll emerge, and the females will start building their tunnels. The males, while the female is hard at work, will patrol the area. Males are harmless, as they have no stinger and cannot sting, but they are curious and may come over to check you out if you wander into their area, which can be very disconcerting. Females do have a stinger and are capable of stinging, but are generally fairly docile, ignoring you if you’re just simply in the area, and will only sting if handled.

When I went up to paint the walls on other side of the house, I discovered this scene underneath the eaves. It looked like the half-developed contents of one of the tunnels had been pulled out by something. Scattered on the shingles were a few chunky larvae, one of which that looked like it was halfway into turning into a pupa, as well as some thick orange chunks. I’m not sure what the orange chunks are, but I suppose them to be the pollen balls that the larval grubs are provisioned with.

I have no idea why these were all on the shingles. If it had been a predator one would think that the grubs would have been eaten, not left to roast on the hot roof. It takes the adult female about a day to provision and seal off each cell, so I was wondering if perhaps the egg that had been laid first had already pupated and emerged as an adult, and as it chewed its way through to exit the tunnel it ended up knocking all the others out. But that seems a bit of a stretch. Maybe a rival female went in and pulled everything out so she could use the tunnel? Also seems a bit of a stretch. I couldn’t find anything online to suggest the reason for it.

The book Insects, by Stephen Marshall, indicates that Eastern Carpenter Bees used to be more restricted to the United States, but in recent decades have been moving north into southern Ontario. Given their strong site fidelity I’m not sure how quickly they spread, or why they would be moving north. However, this may explain why this is the first year we’ve noticed their presence there. They sure seem to like the spot now that they’ve found it!

Carpenter bees are, like most bees, important pollinators in an ecosystem, and many people will tolerate their presence in their buildings despite the damage because they provide a valuable services to their flowers and trees. Unfortunately, pollinators the world over are in decline due to habitat loss and widespread pesticide use, as well as other pressures. A group called Pollination Canada runs a citizen science project where you can make observations on your local pollinators that will help scientists to better understand what’s going on with this very important group of insects.

Daylilies and dragonflies

This is the time of year when my mom’s garden really reaches its peak. It’s a perennial garden, with many different types of flowers, shrubs and plants, but with a focus on daylilies. There are hundreds of cultivars of daylilies, you could fill up acres collecting every one. Mom doesn’t have that many; her collection is somewhere around a hundred cultivars, and was mostly limited by the space in the garden. Most daylilies flower from mid-July through August, and during this time the garden is a riot of colour. The only natural flower colour that seems to be missing is blue, which they haven’t managed to create in the species, perhaps because blue is a structural pigment and isn’t formed through the same processes that produce reds, oranges and yellows. Each bloom on a daylily only lasts one day (hence the name), and a walk around the garden each morning will be just a little different from the previous day, with some cultivars blooming, others not, multiple flowers on some, and first blooms of the summer.

For the last couple weeks, we’ve noticed that the garden is full of these guys, little dragonflies, short and small by dragonfly standards, in red and orange. Dozens of them, all hanging around the garden. They’re meadowhawks, a type of skimmer. About the same length as the damselflies, they can be easily distinguished by their chunky bodies and wings, and oversized eyes. They’re fairly common dragonflies, but there are several species and telling some of them apart can be tricky. A number of species have orangey wing markings, but for those that don’t (and this includes the ones that occur here), the best characteristic is the face. Around here we’re likely to get White-faced, Cherry-faced and Ruby Meadowhawks. There is some overlap in face colour, just to make things confusing, but generally the White-faced have a pure white face, the Ruby has a straw-coloured face, and the Cherry a reddish face (although eastern individuals can be olive-yellow). The book Dragonflies Through Binoculars states that Ruby and Cherry-faced cannot be separated by face colour in the east. The Stokes Beginners Guide to Dragonflies also warns, “A meadowhawk with a dull yellowish or ivory face cannot be identified with certainty in the field.” Rather, definitive identification requires examination of the genitalia under a microscope. And, to throw a wrench in the works, Through Binoculars indicates that all three species hybridize in the northeast, such that intermediate individuals may not belong to one species or another but are instead hybrids.

The brown individuals are all females, or possibly immature males. Male meadowhawks remain this brownish colour for about two weeks before obtaining the bright red of maturity. During this time they’re separable from the females by examining their genital structures, but I didn’t look that closely. It’s interesting how much of dragonfly and damselfly identification comes down to the genitalia. How do the insects know which species another individual is when courting? Are there little visual clues that we haven’t seen, or are too small for our naked eyes? Or do they use behavioural cues? It would be embarrassing to try to hook up with a female just to find your lock and key don’t fit; good thing dragonflies don’t get embarrassed.

More than most other dragonflies I observe, meadowhawks like to perch at the tips of tall pointy things that stick out from the surrounding foliage. It was tough to get a photo of one actually on a daylily bloom because they would favour the long grasses, tall thistle stalks, and even the unopened daylily buds over the flowers themselves. Like all dragonflies, meadowhawks are predaceous, feeding on other insects, using their speed and agility to catch them. I imagine that perching in an exposed location like that offers them the best view of their surroundings, and potential prey, and also allows them to dart out after something without having to navigate around plants. If you watch a meadowhawk closely you can see it turning its head to focus on different things.

I’ve noticed the occasional individual will adopt this pose while resting. It’s called the “obelisk position”, and its purpose is to minimize the surface area of the dragonfly’s body that is exposed to the sun. Since insects have no physiological ability to thermoregulate, they must change their behaviour to prevent overheating. Whereas we would simply sweat and cool down through evaporation, a dragonfly must either seek shade or, where shade isn’t available, or is impractical (such as in hunting in open areas), minimize their exposure to the sun. While most dragonflies are associated with water edges, meadowhawks, as their name implies, are often found in meadows or other open areas that may have minimal shade. Notice how small the dragonfly’s shadow is on the fern frond.

Also interesting to note, the above individual appears to be a male changing from its immature brown into its mature red colouration. You can see the red starting on the top of the abdomen in a couple spots.

In taking close-up photos of a few individuals, I noticed that the pattern of colours and spots on their large compound eyes varied from one individual to the next. For instance, the above individual looks like it has pupils and is smiling at the camera, while the one below has more diffuse spots on its eyes. I wonder if this is a difference in species, in sex (since immature males are the same colour as females), or simply individual variation?