Wednesday, January 30, 2013

A midwinter's feast

During the fall, I would frequently check on the crabapples to see if anything was eating them.  However, back then, they did not appear to be appetizing to anything except coddling moth caterpillars.  Finally, now that it is the middle of winter and there is very little else to eat, the crabapples are attracting more interest.

Crabapples, some partially eaten, covered in frost after a freezing fog.
Over the past couple of weeks, I have seen large flocks of birds, including house finches (Carpodacus mexicanus), occupying the crabapple tree and eating the fruits.

A female house finch (Carpodacus mexicanus) picking a crabapple.
The birds are messy eaters and have littered the ground below the tree with bits of fruit.  These bits, in turn, have been attracting flightless consumers: rabbits, rodents, or both.  Nevertheless, the crabapples are not the top choice for all the animals visiting the yard.  When a flock of cedar waxwings (Bombycilla cedrorum) appeared this weekend, they ignored the crabapples and feasted on the many juniper berries that had also been left uneaten since last summer.

* To see this video in high definition (1080p), you may need to (1) click "YouTube" to watch on the YouTube website and (2) change the settings at the bottom of the video screen.

Monday, January 28, 2013

Cleaned out of house and home

When some of the spotted oleander caterpillars (Empyreuma affinis) looked large enough to leave the oleander tree, I decided it was time to clean away the old, empty cocoons from the surrounding area.

Spotted oleander caterpillar (Empyreuma affinis) cocoons in the corner of a window frame.
I wanted to be able to keep track of the new pupae, but I couldn't do that very easily with tens of cocoons from past generations filling every nearby sheltered spot.  However, I acted a bit too late -- there were already a few new pupae hidden among the old cocoons.  Some were already several days old...

Spotted oleander caterpillar (Empyreuma affinis) pupae.
... and one was still being formed.

A brand new pupa of a spotted oleander caterpillar (Empyreuma affinis).
I kept the pupae in an enclosure and for several days saw no change, except that the youngest pupa darkened to match the rest.  Then, one morning, two of the moths emerged.  Unlike my recent experience with the monarch butterfly, there was no sign (that I could recognize) that the moths were about to emerge; thus, I missed both events.  Later that day, we took the moths to the oleander tree and released them into the open.

The first stop for this recently emerged spotted oleander caterpillar (Empyreuma affinis) moth was my mother's leg.
The moths showed no interest in their host plant, and in this they were exactly the same as the monarch butterfly.  Although one of the moths did rest briefly on my mother's pants (as shown in the picture above), they were both soon headed high up into the trees.

One of the moths resting on a palm frond after its first extended flight.

Friday, January 25, 2013

Breaking the vicious circle

Though whiteflies have become a serious pest in south Florida, they are not without natural enemies.  Many species of parasites, parasitoids, and predators are important in controlling whitefly populations.  In our garden, the most visible threat to whiteflies is from one group of these predators: the lacewings.

An adult green lacewing (Chrysopidae) on a leaf with whiteflies.
An adult brown lacewing (Hemerobiidae) on a papaya leaf.
Lacewings were among the insects that I found most frequently in the garden, especially at night.  I would usually find one or two flying about and many more on the undersides of leaves colonized by whiteflies.  Even so, I was surprised one night to be able to see seven adult green lacewings from one spot -- each one on its own whitefly-covered leaflet of a Schefflera tree.  They did not seem to be actively eating the whiteflies; they may instead have been scouting for places to lay their eggs.

A row of lacewing eggs.
In some lacewing species, both the adults and the larvae will eat whiteflies and other small pests.  In other species, it is only the larvae that are important predators.  Although I did not see any lacewing larvae eating the plentiful whiteflies, I did find several green lacewing larvae roaming the garden in disguise.  Furthermore, from their disguises, I could tell that the larvae had not been restricting their diets to whiteflies.  For example, the larva pictured below seems to have had a large appetite for ants.

A green lacewing larva carrying a disguise of ant bodies.

Wednesday, January 23, 2013

A vicious circle

The mysterious cocoon was not the only odd-looking thing underneath the leaves in the garden.  Many of the leaves were marked with white, waxy spirals.

Eggs of a whitefly (Aleurodicus sp.) on the underside of a palm leaf.
These patterns were made by whiteflies (which are related to aphids and scale insects, not flies).  In some whitefly species, the adult females lay their eggs in spirals and cover them with a trail of wax.

An adult whitefly (Aleurodicus sp.) and eggs on the underside of a papapya leaf.
Although the adult whiteflies look harmless and the egg spirals could even be considered decorative, whitefly larvae are serious pests.  In addition to feeding on plant sap, they can transmit plant viruses when they pierce the leaves and the honeydew that they excrete can facilitate the growth of sooty mold.

A closeup of an adult whitefly on a palm leaf.

Tuesday, January 22, 2013

The thin green line

In addition to nutritionally supporting many caterpillars, the oleander tree was also physically supporting several vines.  One of these vines was about to bloom when I first arrived in Florida, and whenever I checked on the caterpillars I would also check on the buds.  I did not have to wait long before the first bud opened, revealing a very distinctive inflorescence.

An aroid vine (Araceae) with an open inflorescence and several buds.
I was less successful in discovering what was inside a strange object underneath one of the vine leaves.  It appeared to be a cocoon and although most of its silk was yellow, there was a dark green line going down the middle.

The mysterious yellow cocoon (?) with a green line across the middle.
The green line puzzled me -- it made the cocoon more obvious, yet it did not look like the warning signal of something dangerous or distasteful.  I hoped to find answers online, but I could not even find a picture or description resembling the cocoon.  I began to wonder if this cocoon just happened to have been woven in a peculiar way, until I found a second and then a third cocoon with the same green line.  Therefore, it now seems highly unlikely that the green line is just a random pattern; however, why there is a green line and what is behind it remain mysteries.

Saturday, January 19, 2013

Crawling out of its skin

The caterpillars in the backyard are not the only ones that have been growing too big for their skins.  As I was walking by our fig tree, I noticed something tangled among the aerial roots.

A shed snake skin entwined in a fig tree.
A snake had used the twisting roots, with their rough bark and narrow gaps, to hold back its old skin while it kept on going.  I could not identify the previous owner from the skin itself, but one candidate was a southern black racer (Coluber constrictor priapus) that I had seen in the neighborhood earlier that day.

A southern black racer (Coluber constrictor priapus) sunning itself on a wall.
A couple of days later, I found the southern black racer again (or another very much like it) and this time in our backyard. 

A southern black racer (Coluber constrictor priapus) watching me from the foliage.
Despite its somewhat malevolent appearance, this snake is neither venomous nor aggressive.  It can bite if threatened, but it is much likelier to disappear rapidly into the undergrowth (which is the way that both of my encounters ended).

Thursday, January 17, 2013

Bad hair day

Even though a caterpillar's skin appears soft and stretchy, it is an exoskeleton that cannot grow. Therefore, a caterpillar must periodically take breaks from eating in order to molt; it develops a new, larger skin underneath its old skin, which is then be shed.

A queen butterfly (Danaus gilippus) caterpillar just after molting.
The queen butterfly caterpillar pictured above had recently molted.  Its old skin can be seen clasped higher up on the leaf vein and its old head capsule can be seen to the left of the caterpillar.  However, the queen butterfly caterpillar itself does not look much different than usual.  In contrast, a freshly molted spotted oleander caterpillar can be recognized easily by its clumped and curly hair!

A spotted oleander caterpillar (Empyreuma affinis) just after molting.

Tuesday, January 15, 2013

Resisting hibernation

A few days ago, I returned to the cold and snow of Eastern Washington.  Despite days without the temperature rising above freezing, there are signs of life scurrying about.  Rabbits and mice have left trails in the snow and flocks of birds perch in the trees eating last year's fruits.

Rabbit footprints in the snow.
Although the chill weather hasn't sent all the wildlife into hibernation, it is keeping me indoors, where I have been looking over photos from Florida with growing nostalgia.  Therefore, expect to see posts from Florida continuing for the near future!

A zebra longwing (Heliconius charithonia), the state butterfly of Florida, feeding at a flower.

Saturday, January 12, 2013

Rapid hair loss

In addition to being toxic, spotted oleander caterpillars (Empyreuma affinis) are covered in tufts of hairs that look like they could deliver a painful sting.  Some related species do indeed have stinging (urticating) hairs.  Thus, it seemed safest to avoid touching these caterpillars.

A spotted oleander caterpillar (Empyreuma affinis) climbs up a wall to find a place to pupate.
Whether the hairs sting or not, one way that they are used by the caterpillars is in their cocoons.  As a caterpillar spins a loose silk cocoon around itself, its hairs fall out and become incorporated in the cocoon.

A spotted oleander caterpillar (Empyreuma affinis) in its cocoon of silk and hairs.
Once the caterpillar pupates, only a few hairs are left attached to the shed skin (which can be seen to the left of the pupa below).

The early pupa, before it has darkened.
The hairs in the cocoons do not seem to provide protection for the pupae, however.  While clearing away some old cocoons and searching for any intact pupae among them, I ended up touching quite a few hairs without getting stung.

Wednesday, January 9, 2013

A change of costume for a change of scene

When seen from below, small Alope sphinx (Erinnyis alope) caterpillars closely resemble the veins of the papaya leaves upon which they feed.  This resemblance does not seem to be just a coincidence, as every time I checked on them, the caterpillars were sitting either directly on top of a leaf vein or on one of the stems.

A young Alope sphinx (Erinnyis alope) caterpillar camouflaged against a papaya leaf vein.
As the caterpillars ate more and more of the leaves, however, they became considerably larger than the leaf veins and even the leaf stems.  While photographing one of these large caterpillars, I found that it had another trick up its sleeve: an eyespot that it could reveal when threatened.

An Alope sphinx (Erinnyis alope) caterpillar showing its eyespot.
Once these caterpillars finish feeding, they descend to the leaf litter to pupate.  Their bright green color would stand out against the brown of twigs and decaying leaves, but that turns out not to be a problem for these caterpillars either.  The one that I found right below the papaya had adopted a new camouflage more suited to its new environment.

The Alope sphinx (Erinnyis alope) caterpillar that I found in the leaf litter below the papaya.
Another view of the dark form of the Alope sphinx (Erinnyis alope) caterpillar.
Explore some more: Caterpillar eyespots

Tuesday, January 8, 2013

Hungry caterpillars

While the milkweed plants have had a reprieve from monarch butterfly caterpillars, plants in other parts of the garden have been home (and food) to the caterpillars of several moth species.  The most noticeable of these caterpillars are the ones covering the oleander tree.

A spotted oleander caterpillar (Empyreuma affinis) eating an oleander (Nerium oleander) leaf.
These caterpillars have a bright orange and white coloration that signals a powerful chemical defense. Oleanders contain toxic cardiac glycosides, but these do not deter the spotted oleander caterpillars.  In fact, these caterpillars are able to sequester the toxins within their bodies, thus becoming distasteful to many of their would-be predators.

The caterpillars consuming the other plants were more difficult to locate.  The sphinx moth caterpillars on the papaya tree matched the papaya stems and leaves well.  However, they did stand out after they had eaten most of the small papaya tree's leaves.

One of the five Alope sphinx (Erinnyis alope) caterpillars that nearly defoliated the young papaya (Carica papaya) tree.
The caterpillars in the herb patch used two very different strategies to avoid detection, although both were ultimately unsuccessful.  The leafroller caterpillars used the parsley leaves themselves as camouflage by weaving the leaves together...

One of the leafrollers that had been eating the parsley (now in a jar).
...and the dirt brown armyworms ate basil at night and dropped to the soil to hide throughout the day.

An armyworm (Spodoptera sp.) that had been eating the basil.

Friday, January 4, 2013

Upwards and onwards

The day after the monarch butterfly emerged from its chrysalis, the weather was warm and sunny once again.  We gathered in the yard near a flowering milkweed plant, thinking that the butterfly might want a drink of nectar to fuel its first flight.  Although the butterfly had been sitting peacefully on the wall of its enclosure, it was ready to go as soon as the glass panel began to slide up.

The monarch butterfly was eager to be free.
A moment later, the monarch butterfly was free and breezing past the flowers we had positioned in front of the enclosure.  Without any of the awkwardness one might expect from a novice flyer, the butterfly fluttered nonchalantly above our heads and circled the garden a couple of times before settling high in a tree. 

The monarch butterfly resting on a neem tree after its first flight.
After a rest in the tree, a few more tours of the garden, and another rest in the tree, the monarch butterfly was finally off, flying upwards and onwards.

Wednesday, January 2, 2013

Hello new!

Although I waited expectantly to see the monarch butterfly emerge, I did not maintain a constant watch.  I thought that the butterfly would exit the chrysalis slowly, so I sat by the chrysalis and read, only looking up every couple of minutes to see if anything had changed.

The monarch chrysalis eight minutes before the butterfly emerged.
I did not notice any change until mid-morning, when I looked up to find that the chrysalis was puckered open near the bottom.  As I grabbed up my camera, I was shocked to see the chrysalis suddenly split open, spilling the butterfly out.

The monarch butterfly tumbling out of the chrysalis.
In contrast to what I had expected, the butterfly was out of the chrysalis in mere seconds.  It was the expansion and drying of the butterfly's wings that took considerably longer.  At first, the butterfly's wings were notably shorter than its abdomen.  However, over the next twenty minutes, the wings lengthened at an almost visible pace.

The monarch butterfly 0, 9, and 19 minutes after emerging.
By the end of the morning, the butterfly was making very short flights in the limited space of its enclosure.  However, since a storm was approaching, we decided to postpone the butterfly's release until the next day.  To be continued...