The host with the most, part two

The mining flies and galling mites inflicted peculiar injuries to the lantanas, but last year I saw plenty of ordinary herbivory of lantanas too.  Of course, after finding evidence of herbivory, I sought out the herbivores themselves.

A lantana leaf fastened in half by silk.

When the damage was fresh, I did not have to look far before finding the herbivore.  One type of caterpillar, the lantana leaftier moth, made pouches out of the lantana leaves by tying them with silk.  It then consumed the leaf down to a membrane while remaining concealed within the folded leaf (until I came along and pulled the leaf open).

A lantana leaftier moth (Salbia haemorrhoidalis) caterpillar eating the leaf from within.

Another, much larger caterpillar made an even more complete meal of the lantana leaves.  After it had finished with a leaf, there was often not much left besides the tough central vein.

A lantana after a visit from a very hungry caterpillar.

Looking for the first relatively intact leaf adjacent to the consumed leaves, it was easy to find the lantana moth caterpillars that were responsible for the devastation.

A lantana moth (Diastema tigris) caterpillar underneath a lantana leaf.

The host with the most, part one

The bright, multicolored flowers of lantanas attract many insects to feed on the nectar they dispense.

A gulf fritillary (Agraulis vanillae) visiting lantana flowers.

However, a number of other insects specialize on extracting nutrients from lantanas in other, more destructive ways.  Recently, I observed many lantana leaves that had been hollowed out, particularly along and around the veins.

A mined lantana leaf.

Although I did not see any of the leaf miners themselves, the pattern of damage was characteristic of the herringbone leaf-mining fly.

More lantana leaves mined by the larvae of the herringbone leaf-mining fly (Ophiomyia camarae)

Meanwhile, other lantanas were suffering from an even stranger affliction -- they had thick growths of miniature stems and leaves where they should have had flowers and fruits.

Lantana flower gall mites (Aceria lantanae) made this plant produce tiny stems and leaves in place of flowers.

In this case, bud mites were the culprits.  The mites had manipulated the plants into switching from producing flowers to growing more vegetative tissue, which had developed into galls enclosing the mites.

Adding eggs to the basket

Around the time that the tortoise beetles were leaving their eggs on the bindweed, I found two small cabbage white butterflies laying lots of their own eggs in the garden.  Small cabbage whites are native to Europe, Asia, and north Africa -- and so too are the garlic mustard plants that they chose as hosts for their offspring.

A female small cabbage white butterfly (Pieris rapae) on a garlic mustard (Alliaria petiolata) leaf.

The butterflies fluttered from leaf to leaf, sometimes moving on quickly and sometimes pausing to lay a single egg before going off in search of the next suitable leaf.

A small cabbage white butterfly (Pieris rapae) egg.

The butterflies appeared to be spreading their eggs out amongst the available leaves, which made sense to me as a way of reducing the risks of predation, parasitism, and competition.  Therefore, I was surprised by what I found when I went to check on the eggs again later.

Now there are two small cabbage white butterfly eggs!

Where there had been just one egg, there were two eggs.  Even more surprisingly, where there had been two eggs...

Two small cabbage white butterfly eggs underneath a garlic mustard leaf.

...there were seven eggs!

Now there are seven small cabbage white butterfly eggs under the leaf.

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.

All sewn up, part three

After sealing itself up inside the hydrangea leaves, what did the hydrangea leaftier caterpillar do?  From the outside, there was no obvious sign that the caterpillar was feeding on the leaves.

Hydrangea leaves after an encounter with a hydrangea leaftier (Olethreutes ferriferana) caterpillar.

Pulling apart one of the older leaf capsules to see what was happening inside, I found something that did not look very much like a caterpillar.

Nested inside the sealed leaves was a sealed bundle.

It looked a lot like a clump of moldy frass, but I tried separating it anyway -- and out popped a twitching pupa.

Inside the cocoon was a hydrangea leaftier (Olethreutes ferriferana) pupa.

By tying the hydrangea leaves together and then forming a cocoon inside, the caterpillar had made a snug refuge with multiple layers of security to protect it during its metamorphosis into a moth.

All sewn up, part two

A few days after first observing the strange affliction of the hydrangea leaves, I managed to find a set of leaves that were only partially sealed.

Hydrangea leaves partially woven together.

Lines of silk laced back and forth between the leaf margins, leading up to the weaver itself: the aptly named hydrangea leaftier.

A hydrangea leaftier (Olethreutes ferriferana) moth larva.

Weaving the hydrangea leaves together is a big -- and very slow -- job for such a small caterpillar.  Here is a brief clip showing the weaving process up close and then zoomed out to show the extent of the task...

* 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

...and here is a longer clip, played at 32x actual speed, to illustrate how the leaves are pulled together by the caterpillar.

* 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

All sewn up, part one

While checking for insects on the plants around the garden, I noticed that many of the new hydrangea leaves seemed glued together.

Hydrangea leaves tightly stuck together.

Several of the leaves were even deformed from continuing to grow without the room to expand.

More hydrangea leaves stuck together.

Something had tied the leaves together and was hiding inside, but what?  Unlike rolled leaves, there was no opening left between the hydrangea leaves for the occupant to exit through -- or for me to peer through.  To be continued...

Camera shy

A metallic fly on a sunlit leaf should make an attractive picture.  Yet getting such a picture poses a serious challenge.  It is not that the flies are rare, since I often come across gleaming blue, green, and even gold flies perched in the sun.  It is not that they fly away either.  The flies sit still as I line up my camera and are still sitting on the leaves once the pictures have been taken.  However, the flies do not appear in the pictures themselves.

A leaf where a fly had been sitting a moment before.  If you look closely, you can find two of the fly's legs.

In between the time that I press the shutter button and the time that the picture is taken, the flies reliably launch themselves off their leaves, only to land again the next moment.  This amazing disappearing act is possible because flies have extremely fast reaction times.  As soon as the camera begins to flash, the targeted fly initiates its evasive action.  Nevertheless, the flies are not impossible to catch on camera (even when continuing to use the flash).  With some experimentation, it is even possible to capture them in midair.

After many tries, I was also able to take a picture of the fly sitting on the leaf.  Perhaps I had momentarily worn the fly down or the angle of the shot had caught the fly by surprise.

A sneak attack from the rear finally succeeds in capturing the longlegged fly (Dolichopodidae, subfamily Sciapodinae).

 Either way, the fly soon returned to its shy ways.

Can you find the fly's shadow?

Explore some more: Why Flies Are So Hard to Swat

Assassins all around, part one

In the yard in Maine, the most stunning transformation that occurred during the transition from summer to fall was of the burning bushes.  These small trees went from rather modest plants to the most ostentatious ones in the garden, with vividly pink leaves...

Fall foliage of the burning bush (Euonymus alatus).

... and multitudes of brilliantly red fruits.

Burning bush branches loaded with dehisced fruits.

 As I was admiring the burning bushes, one leaf with a bit more green on it stood out from the others.

A pale green assassin bug (Zelus luridus) nymph on the burning bush.

Hanging on to the leaf was an immature pale green assassin bug (Zelus luridus) waiting to grab prey with its sticky forelegs and then stab the prey with its sharp beak.

The assassin bug nymph raising its sticky forelegs in defense, or maybe in preparation for attack!

Though the assassin bug initially seemed disturbed by my attention, I kept seeing it on the same leaf over the next couple of days.  Then, the leaf fell from the tree and the assassin bug disappeared with it.

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).

Wool gathering

In mid July, the flowers in my garden were buzzing with bees -- and so were some of the leaves.  Leaf cutter bees were busy collecting nesting materials from the leaves of lamb's ears (Stachys byzantina).  However, instead of removing segments of the leaves, they were shearing the hairs off the leaves.  In the picture below, several sheared patches can be seen on the lamb's ear leaves, along with a ball of the hairs.

A ball of fuzz on a lamb's ear (Stachys byzantina) leaf.

This ball had been abandoned by a bee when I came close to investigate.  Once I kept still, I did not have to wait long for one of the leaf cutters -- specifically, a European wool carder bee (Anthidium manicatum) -- to land and continue harvesting the hairs.

A female European wool carder bee (Anthidium manicatum) gathering the fuzz from a lamb's ear leaf.

As you may have guessed, the European wool carder bees get their name from this behavior.  To see one of the bees "carding", watch the video below.

* 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

  

After the bees fly off with their lamb's ear hair balls, they return to their nests, which are made of the leaves they cut, and install the hairs as a lining.

March of the larvae, continued

The masses of beetle larvae were not the first to infest the grey alders (Alnus incana) this year.  Nearly as soon as the leaves had appeared in April, large numbers of bluish black beetles appeared on them.

Alder leaf beetles (Agelastica alni) feeding on grey alder (Alnus incana) leaves in April.

These alder leaf beetles (Agelastica alni) spent their time consuming large portions of the leaves -- and mating.

Alder leaf beetles mating.

By mid May, some of the female beetles had eaten so much that their elytra (wing covers) no longer fit over their abdomens.

A female alder leaf beetle in May.

These greatly enlarged females must have then gone on to lay numerous eggs, producing the legions of larvae that would be responsible for even more damage to the grey alder leaves.

March of the larvae

Although I encountered one moth larva crossing the sidewalk, the hundreds of other insect larvae that I have seen recently have been (not very surprisingly) on leaves.  What is surprising is that nearly all those larvae have been on the same few leaves. 

A group of alder leaf beetle (Agelastica alni) larvae eating a grey alder (Alnus incana) leaf.

These unfortunate leaves belonged to grey alders (Alnus incana) and hosted groups of 20+ beetle larvae.  The larvae not only shared the leaves, but also kept in tight formations as they ate their way across the leaves...

The beetle larvae on another leaf leaving a sinuous trail.

...leaving behind them trails of small holes.  However, some of the grey alder leaves were riddled with considerably larger holes.  To be continued...