A tough egg to crack

Last summer, I kept seeing song sparrows and gray catbirds coming in and out of a dense patch of rosebushes.

A song sparrow (Melospiza melodia) emerging from the rose bushes.

I guessed that they had built nests somewhere deep inside.  Although I eventually found the song sparrow nest, I was disappointed that I could not locate the catbird nest.  So, as a surprise, my mother put a wooden egg in an old nest and left it for me to stumble upon.

A large, blue egg in a nest.  (Not a real egg.)

 However, something else found the egg first.

When I heard crows squabbling, I looked out and saw that one of the crows was sitting on the ground by the rosebushes and attempting to eat what appeared to be a gray catbird egg.  Of course, not knowing that a wooden egg had been placed outside just minutes before, I assumed that the crow had found and raided the catbird nest.  The truth only emerged when I shared the sad news about the catbird nest with my mother.  She quickly led me to the nest where the wooden egg had been. As she had suspected, the nest was empty.  When the wooden egg finally reappeared in the yard several days later, it was in splinters.  (The photograph of the egg in the nest above showed a reenactment using a spare egg.  We immediately brought that second egg back inside!)

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...

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.

The ugly larvae, part two

As larvae, tortoise beetles are made distinctly unattractive by the amalgamation of frass and shed skins that they hide beneath.

A green tortoise beetle larva with its fecal shield.

Yet, the beetles undergo a remarkable change when they metamorphose into adults.

A golden tortoise beetle (Charidotella sexpunctata).

Even having seen pictures of the adults beforehand, I was stunned when I saw the shining beetles in the backyard one evening.

A golden tortoise beetle (Charidotella sexpunctata) showing some orange coloration.

That evening, there were many tortoise beetles on the bindweed around the garden and they were from at least two different species.

A mottled tortoise beetle (Deloyala guttata).

However, by the next day, all the adults were gone.  I thought that they might just have gone into hiding for the daytime, but they had not returned to the bindweed by the time I checked again in the evening -- or any time later.  They had left something of themselves behind, though!

Tortoise beetle eggs attached to the underside of a bindweed leaf.

A few days later, the larvae began appearing and were soon devouring all the bindweed.

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

Pricked by the thorn, continued

As adults, treehoppers are not particularly vulnerable.  They are protected, and sometimes camouflaged, by hard, helmet-like coverings.  True to their "hopper" name, they are also capable of launching themselves away from approaching danger.  However, as eggs and nymphs, treehoppers are less self-sufficient.  In order to increase the safety of their offspring, females of the species Publilia concava remain with their eggs after laying them.

A treehopper (Publilia concava) and her eggs, which are embedded in a late goldenrod (Solidago altissima) leaf vein.

By standing over their eggs, the treehoppers can not only guard the eggs, but also recruit additional protection -- in the form of ants.  In fact, the treehoppers do not simply wait for ants to find them; the presence of ants is an important factor in the females' choice of where to lay their eggs.

European fire ants (Myrmica rubra) tending the treehopper.

Like many other insects that feed on sap, this treehopper excretes excess sap as a sugary "honeydew" that is collected by ants to feed their colonies.  Importantly for the honeydew producers, the ants will also aggressively defend their food source.

Field ants (Formica sp.) tending treehopper (Publilia concava) adults and nymphs on a roadside goldenrod.

Explore some more: Ant-dependent oviposition in the membracid Publilia concava

A cradle of roses

As the rose hips ripen here in Maine, they are acquiring both a pretty red blush and quite a few pockmarks.  What has been causing these small scars on the surfaces of the rose hips?

A ripening rose hip with several small, dark wounds.

In the past, I had often seen rose hip flies (Rhagoletis basiola) sitting on and nearby the rose hips.  These flies did not seem to be doing much, though, except sometimes rotating their wings in what may be a mating display.  However, over the last few days, I have caught a couple of the flies in the act --

A rose hip fly (Rhagoletis basiola) ovipositing into a rose hip.

 -- puncturing the rose hips with their ovipositors and laying their eggs inside.

Another rose hip fly (Rhagoletis basiola) ovipositing into a rose hip.

When I waited for one of the flies to finish laying and leave, I saw a fresh hole in the rose hip.  Checking back the next day, I found that the hole had scarred over to match the many other pockmarks on the rose hip.

Ladies in waiting

A little over two weeks ago, I found a cluster of bright yellow eggs underneath a linden (Tilia sp.) leaf.

A cluster of lady beetle eggs on the underside of a linden leaf.

Although I did not need to wait for the eggs to hatch to know what was inside -- developing lady beetle larvae -- I hoped to see the larvae before they dispersed.  Therefore, I made a mental note of where the leaf was and occasionally checked on the eggs.  Finally, after two weeks, there was a change.

The lady beetles shortly after hatching.

The lady beetle larvae had emerged from their eggs.  Soon, they would spread out in search of food.  Checking the surrounding leaves, I saw that the lady beetle larvae would not have to go far to find a plentiful supply of aphids.  However, they would have competitors, as more batches of lady beetle larvae were hatching nearby.

A linden aphid (Eucallipterus tiliae) on a nearby leaf.

Tracing the thin green line

This weekend, I decided to spend some time adding new insects and spiders to my online photo collection.  I was searching for information on one of my new entries, the spinybacked orbweaver spider (Gasteracantha cancriformis), when I stumbled upon pictures of a very familiar object: a yellow oval intersected by a green line.

The egg sac of a spinybacked orbweaver spider (Gasteracantha cancriformis).

I had seen three of these objects in our garden in Florida but had been unable to identify them.  Now, at last, I have my answer -- they were the egg sacs of spinybacked orbweaver spiders. 

Female spinybacked orbweavers produce egg sacs in the fall and winter.  Though the eggs hatch after only a couple of weeks, the spiderlings may remain inside the egg sac for several more weeks before emerging.  Thus, the egg sacs that I saw might still have been full of spiderlings.  In several months, if all goes well for the spiderlings, the females will look like this:

A female spinybacked orbweaver spider (Gasteracantha cancriformis) in the center of its web.

Although the mystery of what was hidden beneath the green line has been solved, I have not yet found any explanation of why the egg sacs are marked with a distinct green line.  There seems to have been more interest in why the webs of this species contain tufts of silk (see the picture above).  One idea is that they are a signal to birds, to prevent them from accidentally flying into the webs.

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.

Saved by the camera

I was standing near the crabapple tree when a dark shape on one of the leaves caught my eye.  As I moved closer, I saw that there were actually two dark shapes -- a parasitoid wasp and a jumping spider. 

A jumping spider sneaking up on an ichneumon wasp.

The jumping spider was stalking the parasitoid wasp, which was preoccupied with laying an egg.  With the spider poised to strike, I thought the wasp had no chance to escape.

The jumping spider closes in on the ovipositing parasitoid wasp.

Mysteriously, though, this was as close as the spider got.  After looking at the wasp for a couple of seconds, the spider abruptly turned and moved back down the leaf.  Perhaps it was spooked by the camera, or perhaps the wasp was simply too large for the spider.  Meanwhile, the wasp continued laying its egg.  A couple of minutes later, it turned to face the site where it had been laying an egg or eggs, then spent some time apparently chewing.

The ichneumon wasp chewing nearby its oviposition site.

Once the wasp had flown off, I turned the leaf over to see what had been parasitized.  What I found was the mine of a tentiform leaf miner, with a hole where the wasp had been facing.

A tentiform leaf miner mine with a hole (on the left) where the wasp appeared to be chewing.

Seeing the spider for the eggs

Not all eggs stuck on plants are difficult to identify.  Determining what laid them is simple when the mother is still there -- as long as you notice her.

I first saw the egg sac pictured below from across the yard.  The white of the spider silk stood out brilliantly against the brown of the plant stem.  As I got closer, I could see the contours of the individual eggs neatly wrapped within the silk. 

A spider egg sac attached to a plant stem.

I wondered what kind of spider had laid them, but deciding that I wouldn't be able to identify them until they had hatched, I began to inspect the seeds on the neighboring stems.  When I looked back at the egg sac from a different angle, I was surprised to find that a rather large spider was standing guard over the eggs. 

The female spider guarding her eggs.

Of course, she had been there all along (as you may have noticed from the first picture).  I had been so focused on the bright white egg sac that I had ignored all the surrounding brown.  I was lucky that on this occasion I had decided to leave the eggs where they were.  If I had attempted to collect these eggs to raise in a jar, I might have gotten a bite instead!

The egg snatchers

Summer is ending and there are fewer flowers blooming in the garden.  As a result, the foliage gets more of my attention.  It may not be changing color yet, but it is covered with insect and spider life.  Earlier this week, I noticed several clusters of small eggs on lamb's ear (Stachys byzantina) leaves and on grass.

I was curious to know what had laid all these eggs.  Although most of them had already hatched, I did not see any insects nearby nor any damage to the leaves from hungry young insects.  Therefore, when I found a cluster with about half the eggs still unhatched, I decided to keep the eggs in a jar and observe what emerged. 

The leaf and eggs in my "incubation chamber": a jam jar with a damp paper towel.

The next morning, I saw my first hatchling -- but it was not the offspring of whatever had laid the cluster of eggs.  Instead, it was a parasitoid wasp.  Some time ago, this wasp must have hatched from an egg laid inside one of the already small eggs visible in the picture below.  It then grew, consuming the insect that was developing in the surrounding host egg. 

A parasitoid wasp emerged from one of the eggs.

Two more days have passed and the first wasp has been joined by several more wasps.  Nearly all the eggs have hatched, but I am no closer to finding out what laid them!