Dogbane beetle

What: The end of summer is the time of the insects! I've been watching the dogbane sprout up new shoots, flower, and finally go to seed over the past three months. Because they're a particularly noxious plant (toxic to almost all vertebrates and many vertebrates - they're related to milkweed which is infamous for its implications for monarch caterpillars), they have insects specialized to feeding on them. Similarly, koalas, which exclusively eat the poisonous leaves of eucalyptus, is specialized to eat one and only one thing. The koala's evolutionary trick was to find a way around the defenses of something so toxic that doesn't have any other predators and then exploit that weakness. So too with the dogbane beetle (Chrysochus auratus). Dogbane is a notorious weed in the midwest, largely because it doesn't have any natural pests that control its population.

On the photo at the bottom, I had actually moved it to a milkweed leaf right next to the dogbane where I found it. There were a number of milkweed aphids on the underside. Once the beetle had crawled to the underside of the leaf it kept stomping its feet and then would fly a few inches to a new spot. It seemed really perturbed by the significantly smaller beetles. After about 30 seconds of "torment" it flew to another leaf.

Pine borers

Posted by Aaron Rosenbluth. Aaron is a sophomore from Cleveland, Ohio studying Natural Resource Planning and Economics. He loves being in the outdoors and is happily a member of the UVM outing club!

What: Two months ago I was in Centennial Woods leaning against a fallen tree taking notes. The sun was out and I couldn't have been happier listening to the summer grasshoppers sing and birds above me chirp. After almost a half an hour out there, I looked behind me at the tree I was leaning against and realized I was leaning against a phenomenon that I've seen countless times over the years, but have never really thought twice about. What I saw was a simply massive maze of tunnels/passages in the wood. The tunnels weren't very deep down - just under the bark layer - about 1cm deep, but it was a fascinatingly huge and sprawling system. I figured these tunnels were created by some sort of insect species, but which one and how and why?

After some preliminary research I quickly realized what type of species I was starting to investigate; species within the realm of wood-borers, or species which eat and destroy wood (Xylophagous species, from Greek "xylon" for wood and "phagus" for eater). These species range considerably in their characteristics (as well as richness, with over 10,000 species of wood-boring insects identified).

• All make unique patterns or “galleries” where they live and lay their larvae, 
• all produce and leave behind unique types of frass (excrement from eating wood), 
• all prefer different species of wood to bore into, 
• and all prefer different levels of health in the tree's which they choose to bore into. 

Once larvae have completed development, new adults will chew an exit hole through the bark and emerge. These exit holes are either round, D-shaped, or ovular. Typically, these wood-borers are insects and arthropod species (beetles, moths, ants, bees) whose larvae are laid in and subsequently mature under the bark layer of trees.

After realizing the tree I was leaning against was once home to massive borer community, I looked around the area (a stand of conifers, mostly white pine and hemlock) and was surprised to find that most of the downed trees in the area had once been host to this same borer species. After researching with Eiseman and Charney's Tracks and Sign of Insects and many hours of poring over internet databases, I was unable to come to a conclusion on exactly what species of borer did this, however I did come to the conclusion that it was some sort of bark beetle of the Curculiondae family within the sub-family Scolytinae (linked at the bottom of this posting is an official Vermont State report on insects which likely contains the correct species). These beetles feed on the cambium layer of trees, creating distinguishable patterns in the inner bark and outer sapwood. It is unlike bark beetles to bore deeper than 3mm into the sapwood layer of the tree, which matches what I observed in my tree. Most commonly, bark beetles will attack a tree that is already injured or diseased, often killing it in the process.

The most basic bark beetle gallery begins with the creation of a mating chamber, from which a female excavates a linear tunnel of uniform width either perpendicular or parallel with the grain of the tree (mine went parallel). On either side of the tunnel, the female creates small little niches and lays an egg in each one. I was able to see these niches in my downed tree species (these were in white pine, Pinus strobus); they look like tick marks that are evenly spread out following the main tunnel (see image above).

Ecological Notes:
Wood borers serve the ecologically keystone task of facilitating tree decomposition by creating holes and channels in the woody tissue, phloem, and bark of the stressed, diseased, or dying trees which they feed on. This allows for fungi to enter the tree and begin decomposition.
http://www.vtfpr.org/protection/documents/FullVersion2009ConditionReport.pdf

Hackberry gall psyllids

Posted by Lauren Lenz. Lauren is a junior at UVM studying Environmental Studies. 

What: While collecting some walnuts from a black walnut tree located behind my house, I noticed that many of the leaves covering my driveway had some curious raised growths on them that resembled blisters. The blisters ranged in color, from a dried up dark brown, to a bright and healthy looking green. I’ve seen this before on different kinds of leaves, but have never quite understood exactly what they are and what causes them. Are the growths some sort of fungus? Do they occur because of an insect? Are they harmful to
the tree or plant?

I did some initial research and concluded that perhaps insects caused these blisters, also known as galls. I contacted Scott Stokoe, Dartmouth College farm manager/educator, and avid naturalist, to get some more information on galls. First, he told me that many people see galls and imagine them to be tumor-like growths that are detrimental to the health of the tree. However, that's not exactly what galls are. He had me look at a goldenrod gall, and instructed me to see if I could see or feel any noticeable differences between the stem of the goldenrod and the gall. I looked and felt, and found no differences between the texture and color of the stem and the swollen gall growing within it. The most amazing thing about galls is that they mimic the growth of the stem, and because of this, do not harm or kill the plant.

Scott explained that a female insect (in the case of the gall on the stem of the goldenrod, the goldenrod gall fly) creates the gall when she lays her eggs in the stem. The laying insect or sometimes the larva itself produce chemicals to create an abnormal growth in the plant which results in a place for the larva to live and grow. We cut into the quarter-sized goldenrod gall and found a small larva inside. We also noticed a pathway to the edge of the gall that did not break the outer wall of the plant. I looked up a bit more information that explained that when fall approaches, the larva burrows a path to the outside edge of the gall, but will not use the “escape tunnel” until it leaves the following spring. Therefore, the goldenrod gall fly larvae will winter inside the gall until the promise of spring arrives.

I went back out to my driveway to get a closer look at the galls that appeared to be growing on the fallen leaves. I identified the leaves as being from a Hackberry (Celtis occidentalis) tree, whose most common leaf galls are created by a type of midge fly called the hackberry gall psyllid, or hackberry nipple gall maker (Pachypsilla sp.). I cut many of them open, hoping to find insect larvae inside. However, while all the galls showed signs that larvae were the previous inhabitants, none of them actually contained a larva. Upon closer
observation, the underside of all the galls had tiny holes in them, where it appears the larva inside may have taken their “escape tunnel” out. When did they leave the gall? When the tree dropped its leaves? What and where are they now?

Ecological Notes: Many plants have various types of galls, in all sorts of different places (petioles, leaves, lead shoots). However, each species of gall-making insect only creates galls in one specific species of plant. Every insect species creates their galls in a particular place on their host plant, and each species creates uniquely shaped galls. Gall making is not limited to insects; galls can also be created by fungi and bacteria!

Where: Burlington, and all over!

Praying mantis

What: Meryl & Julia spotted a hitchhiker in our house today - it apparently came in on one of my sweatshirts. This adult female European mantis (Mantis religiosa) was a blast to watch. They're visual predators, focusing right now on all these late summer, early fall insects like crickets and grasshoppers fattening up for a late breeding season. They move slowly and awkwardly through lawns, relying on camouflage and stealth to ambush their prey. Their "praying" arms are really vicious graspers that clasp onto a prey and don't let go. Here, the lady is just using those forelegs to hold a rear leg that it was cleaning.

Ecological notes: Mantises mate in the fall and lay their eggs in a frothy mess (called an ootheca) that hardens. Eggs overwinter and hatch in the late spring. This time of year they're fattening up stores for laying all those eggs. Oh, and apparently it's a myth that they eat the bridegroom. That only happens in captive settings. They're pretty finicky when it comes to visual stimuli so a lab setting, where they're in a glass case results in some weird behavior. In the video, she responded to my movement, but seemed relatively unperturbed when I stomped my feet against the ground to try and elicit a response. The creepy part was that she was watching me, intently. I think it's extra obvious because she could move her head, but it felt like she was studying me - it reminded me of Muldoon, the Aussie hunter in Jurassic Park, who says of the raptors: "That one... when she looks at you, you can see she's working things out."

Where: My backyard

Other notes: For adult praying mantises, females have much larger thoraxes and their wings are never longer than their bodies, while males are more slender and their wings are longer than their bodies are.

Harvesting Honey

What: Callan, Zac, and I suited up and checked in on our hives. A few weeks ago we added supers to the hives and were hoping that the time for harvesting was finally here. And indeed it was! We gave one of our hives a headstart by giving it drawn out comes at the beginning of the season, and the upper of its two supers was completely drawn out with capped honey and no brood. The super probably weighed upwards of 30 pounds! The video shows a bit about the harvesting process once the frames had been removed from the hive. Zac also shows off some wonderful natural history knowledge.

It was amazing to see how much honey we harvested relative to the size of the super. The ball jars are actually sitting on a deep, which is 9 5/8" deep, whereas the super we harvested from is only 6 5/8" deep (its total volume is only about 1.2 square feet). 

Ecological notes: A lot of the clovers are past their peak and the mints, late season squash flowers, and goldenrods are taking center stage. I've seen the first knotweed flower buds, which is among the last sources of nectar for honey bees before winter sets in.

Where: My backyard

Other notes: We got about 2.5 gallons of honey off of our first harvest. Last year we had an early and a late harvest off of one hive, totally about 5 gallons of honey. Hopefully we will be able to harvest honey from our other two hives this year if we get a good flush of nectar over the next few weeks.

Cicadas

What: After returning from a 8 day trip in Alaska, I'm so grateful to return for the crescendo of summer buzzing through the trees and meadows here in Burlington. Last night Callan and I paddled from North Beach to downtown to listen to the Lumineers play a lakefront concert. Old Crow Medicine Show headlined and we could hear them playing in the distance as we headed back home. I think the clicks from the bats, chirps from the angle-wings, croaks from the green frogs, and zzzzzzipsss from the katydids definitely upstaged them.

Ecological notes: Most of these insects are hard to spot because they're making their noises from high up in the canopy or once you get close they go silent. Occasionally I spot one of the musicians on the ground. Today while walking to the farmer's market I was lucky enough to find a pair dog-day cicadas (Tibicen sp., perhaps T. canicularis) locked together in their nuptial celebration. Lamely, I'm not sure but I think the one on the left is the female.

I took the below photo on May 11th this spring, in which you can see the smaller male copulating with the female - this is a derived behavior, as a primitive characteristic is to have the female on top. Not surprisingly, it's both intriguing and somewhat repulsive at the same time; I can't quite seem to figure out why some insects mate in this position while others like the cicada lock in a position facing away from one another - if anyone knows, please post a comment. I don't claim to be an expert on insect sex (see Dr. Tatiana's Sex Advice to All Creation for that), but from what I can gather the male has a telescoping "penis" composed of an aedaegus, a structure that extends from the abdomen - the rear third of an insect - and an endophallus, which extends further to deposit spermatophores into the female reproductive tract. Insects don't have swimming sperm, but encapsulated spermatophores and so need to be directly deposited to the site of implantation.

Aptly named, the dog-day cicadas are among the later insects to start making their buzzy wing-flapping noises. The related periodic cicada (Magicicada sp.) has a life cycle that results in outbreaks over large geographic areas every 13 or 17 years, depending on species. Both numbers are prime numbers and probably prevent repeated overlap with any would-be predators that might be on 2,3, 4, or 5 year population cycles (a predator with boom populations every 5 years would only over lap with the periodic cicadas every 85 years). Dog-day cicadas appear every year (and are therefore also known as annual cicadas). Not coincidentally, annual cicadas are predated upon by cicada killer wasps, while periodic cicadas are not known to be predated upon by any wasps. To hear a sampling of Tibicen cicadas check out Insect Singers

Where: My backyard and all over Burlington. The image was taken on Latham Ct in the middle of the road and I found a couple of dead ones nearby.

Etymology notes: Dog days refers to when Sirius, the Dog Star is overhead in the sky, which occurs during late summer.

Carolina locusts

What: Just before leaving for Alaska, I was finding great pleasure in taunting the Carolina Locusts (Dissosteira carolina). It seems like any dry lot or gravely path has at least a couple of these every 10 feet or so that will just explode off the ground when you get close enough. While at rest they virtually disappear into the background - unless that background is a blue tarp - but when they fly, their black wings with yellow border stand out (in flight they superficially resemble mourning cloaks).

Ecological notes: Grasshoppers (Order Orthoptera) undergo incomplete metamorphosis (hemimetabolism). So rather than have four distinct life stages (egg, larva - like a caterpillar, pupa/chrysalis/cocoon, adult) as with animals that undergo complete metamorphosis (holometabolism), they have three stages (egg, nymph, adult). Note the different terminology - larva is for animals with complete metamorphosis, nymph for animals with incomplete metamorphosis.

Having distinct life stages allows for a species to partition up habitat between life stages (e.g. monarch caterpillars eat foliage, adults eat nectar) rather than compete for resources. Because nymphs strongly resemble adults (except having underdeveloped wings and no reproductive organs), they might compete for resources. Dragonflies and many other insects avoid this by having aquatic nymphs and terrestrial adults. We can add a new term here: naiad, which entomologists use to distinguish when a nymph will occupy a different environment than the adult. Grasshoppers and locusts, along with many other insects, don't partition up the environment in this way (called paurometabolism).

Each shed of the exoskeleton (called an instar) brings the nymph closer to sexual maturity. With Carolina locusts, they get larger and darker. The females will get larger than males (about 2.5" long). Despite the color changes, at each stage they are nearly perfect at blending in to their background. Perhaps the color change from nymph to adulthood forces them to find new backdrops with which to camouflage and avoid competing with other life stages in this way.

Camouflage is a method of concealment of confusion that allows an animal to avoid detection. There are generally three types of camouflage. Dazzle camouflage totally disrupts a predators judgement about the size, shape, speed, and distance of a prey. Much like this pinwheel, this pattern is disorienteering. A lion attempting to go after a zebra will have no trouble spotting a herd, but might have trouble picking out one from the pack and visually separating it from the other zebras. Military boats took advantage of this patterning in World War I and WWII.

An animal may also camouflage itself by pretending to be something that it isn't. I posted earlier about the beautiful wood nymph moth that conceals itself by mimicking bird poop. Animals that utilize mimesis take advantage of the fact that predators maintain search images for prey items, avoiding cuing in on things that are inedible, like twigs (e.g. walking sticks, geometrid caterpillars like inchworms), bird poop, thorns (e.g. thorn bugs), leaves (e.g. katydids), etc. Mimicry is similar, but here only a body part resembles something else rather than the whole body, like those big glowing "eyes" on the wings of a sphinx moth.

Animals may also use a disruptive camouflage technique, called crypsis, that makes an animal difficult to see. An animal can do this by having a coloration similar to the background, as with the Carolina locust, breaking up its outline, countershading (fish have dark backs, light bellies), or one of the coolest, changing colors, like our native gray treefrog (or is it green?).

The locusts are so good at this. I had not trouble spotting them while they were in the air, but as soon as they landed the game began: trying to spot them in the woodchips, sandy patch, or shadows of grass that they landed in. 

Where: Backyards everywhere

Other notes: While locusts, these aren't the species associated with plagues and/or catastrophic agricultural decimation. While common and widespread, they might only seem more abundant because we come into contact with them more often. They prefer dry, rocky/sandy waste places - where better to find this than a city!

Spring ephemerals - Skunk cabbage (part I)

What: It feels so good to break out Newcomb's Wildflower Guide once again! The spring ephemerals have already emerged and are starting to blossom. Their vibrant greens have given me pause, and I've been thinking about what exactly it means to be a spring ephemeral - what adaptations I'd need to survive. If I were an ephemeral I'd want nutrient rich soil to fuel quick growth, some gnarly chemicals to prevent browsers from gobbling up the first green thing they'd seen in 6 months, a bulb, rhizome, or root that could store copious amounts of energy to emerge quickly in the first warm weather of spring, to be small so growth didn't require excessive energy or time, to reproduce vegetatively in case it was a cold spring and insect pollinators weren't out, and a way of attracting pollinators. So there are definitely some adaptive patterns between our different ephemerals that all allow them to take advantage of that brief moment in a year when the ground is warm and the maple leaves still share the branches with the flowers.

Oh, and a spring ephemeral refers to herbaceous perennial plants (above ground parts die back each year) that have a lifespan shorter than the growing season, usually less than two months in April and May. They have to emerge, leaf out, flower, and go to seed before the canopy closes in and blocks out the shade. I'll be posting updates on spring ephemerals over the next couple of weeks as they continue to emerge in the Burlington area.

The one pictured above is a skunk cabbage (Symplcarpus foetidus). Naturalists love to note this plant's ability to generate its own heat to warms itself up on the cold late winter/early spring days to jump start its growth. I was fascinated by the rotting smell of its flower and swarm of blue bottle flies (Calliphora vomitoria) circling around (pictured above). The ravine I was in grades from ash/maple/oak to hemlock/yellow birch. There's considerably less skunk cabbage 'neath the hemlocks, and the few that were there were considerably further behind in terms of development.

Where: I was finding the skunk cabbage on small flood banks of a brook at Red Rocks. Soils were very silty sands, enriched from calcium rich bedrock upslope. Also seemed higher density in alluvial areas where movement downslope (not just downstream) was enriching the soil.

Boxelder bugs

What: Full on outbreak of the boxelder bugs (Boisea trivittata). Coincides with the flower buds on the female boxelders (Acer negundo) bursting open.

Ecological notes: These population booms are (primarily) associated with female boxelder trees. But then again, a single boxelder tree is only mostly female or mostly male, meaning that on a single tree you can find both male and female flowers, just with one sex being in the vast majority (the fancy term is polygamodioecious). I heard the bugs before I spotted them. It's been so dry here that their rustling in the leaves made them sound much louder than they actually were. At first I thought (and hoped) it was a hibernacula of snakes waking up in the warm (60o) weather. Alas it was not.

Once I spotted the culprit (actually hundreds and hundreds of culprits) my interest was piqued. I'd watched some type of fly by the lake mating yesterday, with their rears touching and the boxelder bugs took the same posturing. The males are the larger of the two and have much brighter orange bellies. They more or less dragged the females over the rocks. Pairings seemed to last anywhere from 2 to 5 minutes or so.

Where: The bugs were lining the train tracks where North Ave crosses over (by the Donahue Sea caves). The whole stretch of the tracks between North and 127 is lined with boxelders, both male and female. The bugs were mostly along the rocks between the rail lines and the horsetails where it was the warmest.

Other notes: I didn't spot any eggs, but the females will deposit them in the bark of the boxelder. Once they hatch, these little guys have a gradual metamorphosis. They can't fly when they're young but develop wings as they get older (the young look like red aphids). Supposedly they eat boxelder seeds. I'd seen lots and lots of seeds this winter on boxelders that had little holes bored into them - I'm not sure if that was from these insects.