The caterpillars eat their match, part two

When they eat the leaves of their host plants, the caterpillars of the orange-barred sulphur butterfly are green.  However, the one that I found was not eating the leaves, nor was it green.

An orange-barred sulphur (Phoebis philea) caterpillar on a Christmas cassia (Senna bicapsularis) flower.  The flower to the right had already been reduced to almost nothing, presumably by the same caterpillar.

Instead, the caterpillar was the same bright yellow as the flower on which it rested -- and which it would soon eat.  The only thing that prevented the caterpillar from blending in with the flower completely was its pattern of black stripes and spikes.

A few minutes later, the flower's style had already been consumed by the caterpillar.

The caterpillars eat their match, part one

Sulphur butterflies are large and tempting targets for my camera, yet they are surprisingly elusive.  Therefore, I was excited to discover one landing repeatedly on a row of Christmas cassia bushes -- and thrilled once I realized that the butterfly was depositing eggs on the plant.

An orange-barred sulphur butterfly (Phoebis philea) laying eggs on a Christmas cassia (Senna bicapsularis).

Even when laying eggs, the butterfly did not remain still for long, but at least it was long enough for me to get close and take a good look.  Then, after the butterfly had visited a few different spots on the bushes, it departed.

The sulphur flying off.  Some herbivore damage is visible on the leaves, but I didn't find any caterpillars feeding there.

Once the butterfly had moved on, I turned my attention to finding the eggs it had laid and any caterpillars that might have already hatched from previous clutches.  I found a couple of eggs on the tips of young leaves.

A recently laid sulphur butterfly egg.

However, the leaves were not where I found an orange-barred sulphur caterpillar feeding.  To be continued...

Happy Halloween!

This fall, I found some natural Halloween decorations hanging in the park by my apartment.  There were spooky, spiky jack-o'-lanterns...

A spinybacked orbweaver (Gasteracantha cancriformis) spider.

...and spooky, spiky skulls...

Another color form of the spinybacked orbweaver.

...all appropriately surrounded by spooky spider webs!

Happy Fourth (Crab Spider)!

Happy Fourth of July!  To celebrate the date, here is a picture with four crab spiders, including one happy spider with a fly.

Can you find all four crab spiders?

In case you had any trouble spotting all the spiders, here is the picture again, with the spider locations marked...

Three female and one male Misumena vatia crab spiders.

 ... and here is a closeup of the happy spider with her large meal.

The most successful of the four spiders, eating a fly.

The spider at the end of the line

A crab spider may hide itself by matching the color of its flower or by constructing a refuge among the petals, but how can an orb-weaver hide on its web?  In an empty web, an orb-weaver is an easy target for its own predators and parasites.  Many orb-weavers avoid this problem by spending the day hidden nearby their webs, but not Allocyclosa bifurca.

Which lump is the spider?

These spiders sit in wait right in the middle of their webs, where they are disguised as part of a line of similarly shaped and colored egg sacs (above the spider) and bundled prey (below the spider). 

A female Allocyclosa bifurca eating prey that had become snared in its web.

Each time I find these spiders, they seem to be doing very well -- with several egg sacs per web and sometimes several spiders on neighboring fronds of the same palm. 

A female Allocyclosa bifurca spider briefly moving out of its hiding spot.

Yet, as successful as A. bifurca's camouflaging may be, it pales in comparison to what related Cyclosa spiders can do.

Out of the old and into the new

Today, millions of New Year's resolutions are going into effect, including many for a new image to go with the new year.  On New Year's Eve, the spider pictured below was also preparing to make changes in the new year.  The spider began its extreme New Year's makeover by dropping out of its old exoskeleton and emerging with a fresh new exoskeleton. 

An orchard orbweaver spider (Leucauge venusta) that had just molted.

However, rather than hoping to lose weight, the spider was preparing to increase in size.  Since the exoskeleton is relatively inflexible, a spider must shed its old exoskeleton and replace it with a roomier one in order to continue to grow.

The spider hanging below its old exoskeleton.

Don't try this at home

In the summer, when it is warm and the flowers are plentiful, the vast majority of bumble bees out and about are female workers.  Instead of reproducing themselves, these workers collect nectar and pollen to feed to their mother (the queen) and their many younger siblings.  However, the workers are not all completely sterile.  After the queen dies towards the end of the season, some of the workers may begin laying eggs of their own.  Even though these eggs are unfertilized (since the workers never mated), they are still viable -- and they will all develop into males.

A male orange-belted bumble bee (Bombus ternarius) visiting a flower.

In bumble bees, as well as other Hymenoptera, the females are diploid (having two sets of chromosomes and developing from fertilized eggs) and the males are haploid (having only one set of chromosomes and developing from unfertilized eggs).  A consequence is that as bumble bee colonies begin to decline in the fall, more and more of the bumble bees visible on flowers will be males.

A male common eastern bumble bee (Bombus impatiens) visiting a cosmos inflorescence.

Male bumble bees differ from females in the number of their antennal and abdominal segments, the structure of their hind legs, and, in some species, the size of their eyes and the length and color of their hairs (especially on the head).  For example, notice the yellow fuzz on the face of the male bee below.  In the females of this species, the hairs on the face are black.

A very fuzzy male Bombus ternarius resting on a rock.

An important, and potentially less subtle, difference between male and female bumble bees is that only the females sting.  Bee stingers are modified ovipositors, which bees' ancestors used to lay eggs.  Since only the females had ovipositors, only female bees now have stingers.  Not only are male bumble bees unable to sting, they are also quite docile; many of the male bumble bees I found would tolerate being petted gently without flying away.

The bee was very fuzzy indeed!

Please note that I do not recommend trying this yourself (unless you have also worked extensively with bumble bees and are confident that (a) you can correctly identify the males and (b) you are not allergic to bumble bee stings).  Although less common in the fall, female bumble bees are still present and they may sting -- repeatedly -- with little provocation.

A male (above) and much larger female (below) Bombus impatiens.

Explore some more: Bumble bee identification and see more pictures of male bumble bees at the Natural Current Events Facebook Page.

Happy Halloween!

Is your Halloween costume ready?  The females of the dragonfly species known as the "Halloween penant" stay "dressed" in orange and black their entire adult lives.  Yet, they are only likely to be seen on Halloween in the southernmost (and warmest) part of their range -- Florida.

A female Halloween pennant (Celithemis eponina).

What's that bug? continued

After identifying the lobate lac scale, I thought I would try to identify another of the unusual looking bugs in the "Hemiptera" folder.  The larva pictured below seemed like it ought to be easy to identify due to its distinctive appearance, including branched spikes and secreted covering.

A strange, spiky larva on a leaf.

However, the closer that I looked at the picture, the more I began to doubt that it really was a hemipteran.  But if it wasn't a bug, what was it?  Browsing through the various orders of insects, I stumbled across a picture that looked both strange and familiar -- a match for one of the insects in my "Unknown" folder.

An adult male narrow bark louse (Graphopsocus cruciatus) on a rose hip.

The tiny mystery insect was a narrow bark louse, a distant relative of parasitic lice with a much more agreeable diet of plants, lichens, and fungi.  Returning from this lucky digression to the problem of the spiky larva, I eventually came across a surprising answer.

A tortoise beetle larva with its "fecal shield".

The larva was an immature tortoise beetle and possibly a golden tortoise beetle (Cassida sexpunctata), which is considerably more attractive as an adult.

What's that bug?

While I immediately recognize a few of the arthropods in my photographs, I have to file away many of my pictures for later identification.  Most of these can initially be filed to family or at least order, but a few remain complete mysteries.  The strange, butterfly shaped scale insects pictured below lingered anonymously in my "Hemiptera" folder until I serendipitously came across a similar picture when looking for images of invasive species.

Lobate lac scales (Paratachardina pseudolobata) in South Florida last December.

Further research on the internet confirmed that these scales do belong to an introduced species, the lobate lac scale (Paratachardina pseudolobata).  However, learning more about this insect just raised more mysteries.  Although the lobate lac scale is not thought to be native to Florida (or the Bahamas or Christmas Island, where it is also found), it is not clear where this species came from.  A related species (P. lobata) is known from India and Sri Lanka, so this species is likely to be Asian as well.  The spread of this species -- from wherever its native range is -- is somewhat surprising, given its lack of wings and the fact that adults remain relatively sessile.  Also unusual is the absence of males; unlike its relative P. lobata, this scale reproduces parthenogenetically (asexually), developing from unfertilized eggs.

Explore some more: Featured Creature: lobate lac scale

More than a pain in the neck, continued

After noticing the pattern in how candy stripe spiders tackle their prey, I decided to look back at my many pictures of crab spiders for comparison.  As I had thought, the crab spiders also frequently bit their prey just behind the head.

A female Misumena vatia crab spider eating a tricolored bumble bee (Bombus ternarius) in 2012.

The crab spiders took a different approach, however, when their prey was a hover fly (Syrphidae). 

A juvenile crab spider eating a hover fly (Syrphidae) in 2012.

In these cases, as illustrated in the pictures above and below, the crab spider bit right into its victim's abdomen.

Another crab spider eating a hover fly, this time on a snapdragon.

In addition to having a soft abdomen, hover flies are relatively easy for crab spiders to catch.  One way for hover flies to compensate for their vulnerability is to spend more time inspecting landing sites for potential danger; indeed, hover flies can often be seen seemingly suspended in the air above flowers before touching down to feed or darting quickly away.

Two hover flies inspecting a flower before landing.

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

It's a fly eat fly world too

Spiders eat spiders.  Spiders eat flies.  So far, no surprise.  But did you know that there are some flies that eat other flies?

A robber fly (Asilidae) with another fly it has just captured.

These predatory flies are commonly --and rather euphemistically -- called "robber flies".  Robber flies (Asilidae) snatch flies and other insects in flight, inject them with a mixture of paralyzing and digesting enzymes, and then consume the liquefied remains.  Thus, they are also referred to by some by the more appropriate name "assassin flies".

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

The scourge of the spurge

On my last day in France, I stumbled upon a small garden that I had visited once (also while wandering around a bit lost) almost six years before.  I remembered the garden as being full of bright flowers and buzzing insects, but on this cold spring day everything seemed green and still.  However, as I continued along the narrow path, I discovered that not all of the green was simply foliage.  All along the back of the garden, spurge (Euphorbia sp.) plants were topped with light green inflorescences full of little flowers...

One of the many flies that I found visiting the spurge (Euphorbia sp.) flowers.

... and also surprisingly full of large flies, given the lack of pollinators everywhere else I had looked.  I began to get my hopes up -- where I could find flies, I might also be able to find a spider.  A few plants later, there it was: a small spider, but with a good chance of growing larger very soon.

A small spider lurking amongst the spurge flowers.

Les pigeons terribles

Although I was disappointed that there were no insects in the flowers, I did observe some flowers  receive a visitor of another kind.  As I was walking along and admiring the blossoms on a group of small fruit trees, my eye was caught by a large shape that dropped onto one of the branches, bending it nearly to the ground.

The common wood pigeon (Columba palumbus) just after landing in the tree.

The bird that had landed was a common wood pigeon (Columba palumbus), which is considerably larger than the standard pigeon (a.k.a. rock pigeon or rock dove, Columba livia).  I was surprised that the pigeon had landed on a branch that could barely support its weight -- and I was even more surprised when the pigeon turned towards the nearest bunch of flowers and ate them. 

A common wood pigeon (Columba palumbus) eating the pretty flowers.

The pigeon then proceeded to eat all the flowers it could reach from its precarious perch.  Later on, I was no longer surprised to find that not only are these pigeons shameless, they are fearless as well!

A common wood pigeon (Columba palumbus) calmly sitting tête-à-tête with an eagle.

La maison des insectes

After a few mild days in Florida, it was time for me to return to winter -- or rather, à l'hiver.  I arrived in France on a warm and sunny day, which was abruptly followed by several days of bitterly cold winds and snow flurries, then several more days of rain and sleet.  Nevertheless, many early spring flowers were blooming and I was determined to see them -- and check them for insects and spiders.

Crocuses blooming in the Jardin du Luxembourg in Paris.

However, there did not seem to be any insects that were similarly determined to disregard the weather and visit the flowers.  After finding a sign warning that there was a 'danger' of bees, I had a bit of hope that I might at last encounter some insects.

"Do not walk on the lawn. Danger bees."

Yet, even at the headquarters of the dangerous bees, all was quiet.

The hives of the danger bees.

Apparently, the bees were spending a quiet day at home in their hives.  Meanwhile, were all the other insects left to fend for themselves in the elements?  Mais, non!  They could retreat to their very own refuges within the Maison des Insectes.

A shelter for many other beneficial insects.

Explore some more: Build your own insect house

A green and white knight

As I was strolling through a nearby botanical garden, I heard a rustling sound coming from a bush alongside the path.  After searching for a moment, I located the source: a green lizard that was considerably larger than any of the anoles in our garden.

A green lizard with white markings amongst the foliage.

Although I expected the lizard to scurry off as I approached, it did not.  Instead, the lizard froze, and I was able to get a closer look at it.

A juvenile knight anole (Anolis equestris).

However, a closer look just convinced me that I had never seen a lizard like it before.  I thought that the distinctive-looking white bands would make identifying this lizard a simple task.  In fact, it was the reverse.  I eventually learned that the white bands are only present in some juveniles (possibly only the females) of this species: the knight anole (Anolis equestris).  In contrast, the stripes below the eyes and above the shoulders persist into adulthood; these can be used much more reliably to recognize the knight anole, which is yet another species introduced to Florida from Cuba.