The caterpillars eat their match, part three

Compared to the orange-barred sulphur butterflies, adult geometrid moths do not appear very active (at least not during the day)...

A pale beauty moth (Campaea perlata).

...and most of them are not very bright or flashy.

A large lace-border moth (Scopula limboundata).

However, geometrid caterpillars can be just as impressive as orange-barred sulfur caterpillars when it comes to blending in with the flowers that they eat.

A purple geometrid caterpillar on purple flowers.

In addition, at least some geometrid caterpillars have the same ability to change their color in order to match their background.  

A pink geometrid caterpillar on a pink rose blossom.

Although many geometrid species feed on other parts of plants (and mimic those instead), there are well over a thousand species of geometrid moths in North America -- including plenty of ones with colorful, flower-eating caterpillars.  See a few more of them here: Geometrid larvae on flowers

Heart of the stone

Lichens are a classic example of symbiosis -- the close association of two or more species.   In fact, the word "symbiosis" (literally, "together living") was coined in order to describe lichens.  The structure of a lichen is formed by a fungus.  Meanwhile, cells of algae and/or cyanobacteria are embedded within the fungus and perform photosynthesis to capture energy.  Although symbioses are not always harmonious relationships, the lichens pictured below appear to be the symbol of affection.

Lichens on a rock.

Explore some more: The lichen symbiosis - what is so spectacular about it?

Happy Thanksgiving!

To celebrate the holiday, I'm sharing this nice turkey I caught (just on camera, of course).

A wild turkey, making a hasty retreat.

A stitch too late

The hydrangea leaftiers wrapped themselves in multiple layers of protection, but what did they need to be shielded against?  Another group of caterpillars that I encountered over the summer illustrated a potential danger.  These caterpillars were also busy tying leaves.

Woven together leaves.

However, as they built their shelters, they were exposed on the exterior of the leaves.

A caterpillar, probably of a tortricid moth (Tortricidae). 

One of the vulnerable caterpillars exhibited evidence of a recent attack: two parasitoid eggs attached to its body.

A caterpillar with two parasitoid eggs on it.

Even if this caterpillar escaped the attention of predators and hid itself within the leaves, it was probably the parasitoid larvae that benefited from the shelter in the end.

An agreeable face

To move on from a rather disagreeable tail, here is an agreeable face...

An agreeable face?

... or at least, the face of an agreeable tiger moth (Spilosoma congrua).  Certainly, there is something about this particular specimen that makes it seem distinctly less than agreeable.

The agreeable tiger moth in full.

From the point of view of gardeners, however, these moths should indeed be an agreeable sight.  Adult moths produce caterpillars -- and the caterpillars of this species eat a variety of troublesome weeds, including dandelions (Taraxacum spp.), knotweeds (Polygonum spp.), plantains (Plantago spp.), wild lettuces (Lactuca spp.), and white goosefoots (Chenopodium album).

Explore some more: HOSTS - a Database of the World's Lepidopteran Hostplants

A sticky situation

Even when the beaver ponds are empty of beavers, they are home to a wide diversity of other inhabitants.  Insects are especially numerous -- and where insects abound, so too can their consumers.  In particular, the beaver ponds provide an excellent habitat for carnivorous plants, such as pitcher plants and sundews.

A patch of sundews (Drosera sp.).

Around some of the beaver ponds, the sundews form a red carpet that is both enticing and deadly (at least for insects).

A close-up of the leaves with their sticky tentacles.

Each small sundew leaf is studded with dozens of red tentacles, each of which ends in a dewy ball that glistens in the sunlight.

Another view of the leaves.

These sweet droplets attract insects near, then stick to and engulf any hapless insect that comes into contact with them.

A crane fly (Tipuloidea) caught by the sundew.

Insects trapped in this way are digested by the plant, providing an important supplement to the boggy, nutrient-poor soil.

Eager for lily pads

A few days after my surprise encounter with a swimming beaver, I went on another walk around the beaver ponds.  I had hoped that the beaver I had seen before might be back patrolling its pond, so I was disappointed to find the pond empty (at least of visible beavers).  However, I did not give up, and in a pond a short way down the path, I found two beavers.

A beaver eating a rolled up lily pad.

These beavers were busy with the important task of rolling up and eating lily pads.  One after another, the lily pads disappeared into the beavers.  Fortunately for the beavers, the pond was so full of lily pads that an imminent shortage seemed unlikely.

* To see this video in high definition (1080p), you may need to: 

(1) click "YouTube" to watch on the YouTube website

(2) change the settings at the bottom of the video screen

Lap swim

While on walks in Maine, I frequently come across fresh evidence of beaver activity.  However, the beavers themselves are more elusive.  Beaver ponds seem like the obvious places to look for beavers, so each time I am near one, I scan the water...

A beaver pond with its telltale drowned trees.

... and sometimes even spot a beaver-shaped object... only to realize a moment later that it is only a rock or a log.  The beavers' lodges are easy enough to find, but never appear to be the sites of much activity.

A beaver lodge in the beaver pond.

On this particular occasion, after satisfying myself that there was no beaver in the pond or by the beaver lodge, I started photographing some insects and a frog at the edge of the pond.

A frog by the side of the beaver pond.

Then, when I looked up again, a movement in the water caught my eye.  To my great surprise, it was a beaver!

A beaver!

The beaver was swimming just a few feet from where I was standing at the edge of the pond.  I was startled by it, and it may also have been startled by me, since it made a large "plop" with its tail and dove underwater.  Happily for me, though, the beaver soon resurfaced and started swimming back and forth across the pond for several minutes.

* To see this video in high definition (1080p), you may need to: 

(1) click "YouTube" to watch on the YouTube website

(2) change the settings at the bottom of the video screen

Congratulations, you survived! (A Father's Day sentiment)

For crab spiders, becoming a father is a perilous endeavor that involves a lengthy search culminating in a cautious approach to an uncertain ending. While on a walk this Father's Day, I spotted a would-be father that had been insufficiently cautious.

A female Mecaphesa sp. crab spider eating a male.

Whether or not that male crab spider had succeeded in becoming a father, it had succeeded in becoming a meal and was indirectly nourishing a new generation of crab spiders.

A spiderling on another flower.

So, even if human fatherhood has its trials, be glad you aren't a crab spider.

The king of hearts

Happy Valentine's Day!  To celebrate, here is a photograph of one of the most remarkable -- and occasion-appropriate -- insects that I have seen recently: a dragonfly covered in red hearts.

A male calico pennant (Celithemis elisa).

If you look closely, you can see two hearts inside the large dark splotches on the dragonfly's hindwings in addition to the four hearts (and one broken heart) on the dragonfly's abdomen.  Female calico pennants have a similar pattern, but with yellow markings instead of red ones.  Therefore, the females bear a close resemblance to their close relative (and another holiday dragonfly), the Halloween pennant (Celithemis eponina).

Mild and woolly

During a walk through the woods in the fall, it can be tempting to gaze at the trees and their marvelous array of colors, sparing little attention to the ground below.

The woods on a quintessential autumn day.

However, it is still important to look down every once in a while -- and not just to avoid tripping.  Paths through the woods are often shared with animals that are an unfortunate combination of small, slow moving, and easily squished. 

A banded woolly bear caterpillar (Pyrrharctia isabella).

Moreover, while the trees in their autumn foliage emanate a certain serenity, finding a fuzzy caterpillar is much more exciting (at least for me)!  Finding this caterpillar was particularly exciting, as when I got close to see its face...

Facing down the woolly bear.

...it suddenly whipped around into a ball (reminding me of another caterpillar's surprising reaction).

The banded woolly bear in a defensive posture.

Though curling up is unlikely to be a good defense against shoes or wheels, the caterpillar's response did make it easy for me to roll it off the road and out of harm's way.

Going for a ride? Take a Beetle or a Vespid!

Since I am sitting in an airport, it seems like a good time to write about travel.  Though insects seem small from our perspective, many of them are able travelers.  They can cover long distances by walking, jumping, swimming, digging, and flying.  Additionally, they can use their sensitive antennae to detect faraway food (such as carrion, in the case of the burying beetle shown below).

A tomentose burying beetle (Nicrophorus tomentosus) attempting to scurry away from the camera.

These characteristics make insects an attractive mode of transport for a group of much less mobile arthropods: mites.  If you look closely at the burying beetle below, you can see the mite that had crawled out from some hidden spot onto one of the beetle's wing covers (elytra).

A mite (Poecilochirus sp.) riding on the back of the tomentose burying beetle.

Poecilochirus mites are commonly found riding on burying beetles, since these mites also need to get to carrion in order to feed.  Some Poecilochirus mites consume fly eggs and larvae on the carrion, while some are predators of the burying beetles' own eggs.  Meanwhile, other mites prefer foods unrelated to carrion and, correspondingly, take different forms of transport in search of those foods.

A group of mites rides on the back of the thorax of a mason wasp (Vespidae).

Are mites at best hitchhikers or free riders?  Perhaps not, as some evidence suggests that insects can benefit from the mites too.

Explore some more: Parasitic mites as part-time bodyguards of a host wasp

Winsome invaders, lose some invaders

Of the thousands of invasive Japanese beetles that I see each summer, a small number have white ovals stuck to them.  These white ovals, which are the eggs of the parasitic "winsome fly" (Istocheta aldrichi), are usually attached to a beetle's pronotum (just behind the head) or sometimes to its elytra (the hard coverings over the wings).  Although the eggs do not look like much, they mean that the beetle has only a few more days to live.

Mating Japanese beetles (Popillia japonica); these beetles are unlikely to have any offspring, however, since the female has several winsome fly (Istocheta aldrichi) eggs glued to her.

About a day after the eggs are laid, larvae hatch from them and bore into their beetle host.  After a few more days, the beetle dies, eaten from the inside by the fly larvae.  Like the Japanese beetles themselves, winsome flies were introduced into North America from Japan.  Unlike the Japanese beetles, the flies were introduced intentionally -- in the hope that they would restrict the growth of the Japanese beetle populations.  However, it has now been more than 90 years since the flies were first introduced, and the Japanese beetle remains a growing problem.

Explore Some More: Biological Control of Japanese Beetles

Purple insect eater

In most consumer-resource interactions between plants and insects, the plant is the one that gets consumed.  However, a few groups of plants have been able to reverse the relationship.  Insects and other small animals come to these plants for a meal, only to become one themselves.

A purple pitcher plant (Sarracenia purpurea) in bloom.

One of these carnivorous plants, the purple pitcher plant (Sarracenia purpurea), lures visitors onto its leaves with colorful markings and nectar secretions.

Dead insects, including a moth, in a pitcher plant leaf.

Once on a leaf, visitors become trapped due to the leaf's waxy surface, steep angle, and downwards pointing hairs -- and possibly due to being drugged (a narcotic compound has been found in the secretions of a related species, S. flava).  Even flying insects fall into and then drown in the pool of rainwater at the base of the leaf.

Flies and springtails trapped in another leaf.

This water also contains digestive enzymes secreted by the leaf and a community of bacteria, which together break down the victims of the trap.  The leaf can then absorb nutrients that the plant might not otherwise be able to obtain from the poor quality soil in its boggy habitat.

A carabid beetle attempting to escape the pitfall trap.

Know thy host, continued

By now, it should not come as much of a surprise that I go to gardens to look for insects more than to look at the plants themselves.  The wide variety of plants in gardens attracts a diversity of insects, especially when the gardeners prioritize native plants (and refrain from spraying pesticides all over).  On this particular garden trip, I started out by looking for plants with leaf damage and soon came across a patch of plants that appeared to have been hosting a feast.  However, standing above the plants, I did not see any of the feasters; were they still there?  Spotting some frass (insect droppings) on one leaf, I crouched down to inspect the overhanging leaf.

A larva on the underside of a leaf with some frass below.

I had expected to see a caterpillar and what I found was caterpillar-like, but its spiral pose instantly made me suspicious.  When I flipped the leaf over to get a better look and saw its eyes, my suspicion that it was not a caterpillar was confirmed.  (If it had been a caterpillar, I should not have been able to see its real eyes.)  Instead, it was a sawfly -- a relative of wasps and bees.

A sawfly larva (Tenthredo grandis) curled up in a characteristic pose.

Once I had found the first one, it became easier to find even more of the sawfly larvae.  From one of these that wasn't curled up, I could see another distinctive difference: the larva had too many legs to be a caterpillar.  (Caterpillars have five or fewer fleshy "prolegs" after the first three jointed, true legs; sawfly larvae have six or more prolegs.)

Another sawfly larva (Tenthredo grandis) on a nearby leaf.

Recognizing the larvae as sawflies was an important step towards identifying their species.  Identifying their host plant would expedite the rest of the task.  Luckily, identifying this host plant as white turtlehead (Chelone glabra) only required some simple inference.

There was no need to work through a key to identify this plant!

Explore some more: Wild Gardens of Acadia and Lepidopteran vs Sawfly Larvae

Know thy host

Picking the right spot to lay eggs is a challenge shared by many insects.  While most adult insects can fly, immature insects tend to be more limited in their movement.  Therefore, in addition to the safety of her offspring, the mother must ensure the availability of the right food -- and in adequate amounts.

A common aspen leaf miner (Phyllocnistis populiella) about to run out of leaf to eat.

Perhaps the mother of the leaf miner larva above should have chosen a bigger leaf.  Yet, young (and thus small) leaves may confer their own advantages, including being more tender and consequently easier to eat.  Indeed, young leaves are often preferred by a variety of herbivores.

On a side note, how does one identify an insect that is still inside a leaf?  The trick is to know the leaf.  Since leaf miners tend to be specialized on one or a small number of plant species, identifying the plant can lead to the identity of the leaf miner.  For example, identifying the leaf above as belonging to a quaking aspen (Populus tremuloides) quickly led to the identification of the larva inside.  Even when more than one leaf miner species uses a plant, the leaf miners will usually differ in the type of mine they create (see some other examples here and here).

Labor Day Special

In celebration of Labor Day, I'm posting pictures but leaving the rest of the work to you: find the insects hiding in plain sight!

If you couldn't find the insect camouflaged against the lichen on the rock, try again with this closer view.

If you thought finding the insect above was too easy, here is more of a challenge.  

Could you find the insect sitting on the leaves?  Here is a close up that might help.

If you still want help finding the insects, or if you would like to know more about them, check the Natural Current Events Facebook page later this week.

A dirty job

On the same excursion during which I encountered the strangely attractive crab spider, a fellow walker called my attention to a wasp that was on the path.

A mason wasp (Eumeninae) collecting mud from the ground.

The ground was still moist from rain in the previous days and the wasp appeared to be digging in the mud with its mandibles.  Then, as I was pressing the shutter button of my camera, the wasp suddenly took flight.  By chance, the wasp and the mud ball it was flying off with were caught in the picture.

The mason wasp flies off with the mud ball held in its mouth.

What could a wasp do with mud?  It could build the walls of a nest!  I had seen similar wasps around the house which had done just that.  The wasps had constructed their mud nests in crevices and had progressed to provisioning the nests with food.  In the picture below, you can see a mason wasp's nest in the frame of one of our windows.  Just inside the entrance to the nest, part of a green caterpillar (a.k.a. food for the wasp's offspring) is still visible.

The nest of another wasp, complete with a green caterpillar to feed the wasp's offspring.

Keeping the enemy closer

While I was out for a walk, I came across a spider that was even more notable for abstaining from eating flies than the jumping spiders on the roses had been.  This spider had flies walking all over it, yet it made no move to catch them.

Flies sitting on a crab spider as it waits in ambush.

The flies were not in blind spots (crab spiders have eyes facing forwards, sideways and backwards); nevertheless, they may have been in the safest spot around.  Though the flies were tantalizing close, the spider may not have been able to reach around to grab them.  Another possibility could have been that the spider was simply waiting for larger or more appetizing prey to come along.

A bigger prey is a better prey?

However, as I was quickly being left behind by the rest of my group, after watching for only a little while longer, I left the spider to its hunting and the flies to their death defying stunts.