Monday, August 07, 2017

Syrphid Fly Scouting Place to Lay Eggs

In my recent post on aphids and their predators, I shared photos of two types of syrphid fly larvae that I am seeing.  A few days later I was lucky enough to get this photograph of an adult syrphid fly, looking for a place to lay eggs on my milkweed.

If you click on the photo, you can see the details that are not apparent in the smaller image imbedded in the text here.  Note the aphids at the base of the flower cluster?  There aren't a lot and I didn't see the female syrphid fly lay any eggs, so she may have decided that she needed to look for more populous aphid clusters.

Going by the Latin name of Ocyptamus fuscipennis, there is no common name for this syrphid fly.  I am pretty sure that this is the adult form of the "gray slug" syrphid fly larva that I see munching on oleander aphids. 


Here is a closeup of this individual....



(Note:  I have not raised an individual from larva to adult to know for sure, but this is both the most common syrphid fly that I see laying eggs on the milkweed and the most common adult syrphid fly larvae that I see.  Others have raised this species from larva to adult, and the larva does look very similar to this.)

What predators are you seeing munching on YOUR aphids?!

Friday, August 04, 2017

Sand Wasp Grows Entirely On True Bugs

When I first saw this good-sized wasp, I thought it looked a lot like a cicada killer.  I couldn't get very close to it to get decent photographs, but I was able to get good enough images that I knew it wasn't my old friend from Kansas.

Tonight, after I cropped the photos to more closely see the insect I had "captured", I tabbed over to BugGuide.net and started looking around.  After a while, I thought I had probably figured out the identification...but the eye color was wrong and the markings on the thorax were not quite right either.  So, I posted the photos and asked for help.

Meanwhile, I continued searching through BugGuide, looking for a better match to my mystery wasp.  As I was checking out a particular species, a sand wasp that is known only as Bicyrtes quadrifasciatus, I saw a couple photos that looked remarkably familiar.  When I checked my email, I was stunned.  My original identification had, indeed, been wrong;  the species I was looking at now was the correct species; and - most surprising of all - one of the contributing editors at BugGuide had already made the identification and moved my photos to the correct spot!   Those WERE the photos I had just uploaded a few minutes before.

BugGuide for the win!

So why do I try so hard to identify "my" insects to the correct species?  This wasp is a good example.  By learning the identity of this wasp, peacefully feeding at a flower, I learned that I host a species of solitary wasp that raises its young completely on true bugs, on insects like stink bugs and assassin bugs and maybe even milkweed bugs.

Seriously.  This species of wasp finds enough true bugs in the general area of my yard to raise its entire brood of young for the year on the bugs that it finds and paralyzes, drags back to its nest, and lays eggs on.  Isn't that incredible?  Talk about natural pest control.  Talk about the "balance of nature".

To top it all off, as an adult, this wasp acts as a pollinator on flowers in my garden.  Before I started learning about the specific identities of the insects in my garden, I had no idea that wasps were such extraordinary predators or that adult wasps generally just ate pollen and nectar.  Based on a childhood experience, I was actually quite scared of them.  Now wasps fascinate me, and the more I learn, the more fascinated I become.

I am continually stunned by the complex interactions occurring all around me - interactions that I simply don't see or even know to look for.  The natural world is truly a marvelous, intricate web of life whose structure we would be wise to cherish, rather than destroy.

Thursday, August 03, 2017

Predators and Parasites on Oleander (Milkweed) Aphids

My milkweeds are hopping these days.  Sadly, I've only seen one monarch caterpillar, but I am still fascinated by all the insect life that I am seeing.  Most of my observations have been on tropical milkweed (Asclepias curassavica) simply because I have several big, healthy plants in pots on my back patio and they are easy to check on and photograph, but I'm fairly certain that what I'm seeing isn't unusual for other milkweed species.

The orange-yellow oleander aphids (Aphis nerii) are common on these plants.  A week ago, when many of these photos were taken, the aphids covered about 2-3" of the top of every shoot.  This week their numbers are much reduced, with just a few hardy individuals remaining where hundreds dined last week.  This is at least the second rise and fall of aphid numbers on my plants this summer.  I'm sure they will go through at least one more population cycle up and down before frost comes this autumn.

So what's keeping the aphid populations from exploding out of control?  If you look closely at the photo above, you can begin to see the answer.  Specifically, here are some of the candidates I've been seeing....

Each milkweed shoot with its covering of yellow aphids near the tip seems to also have at least one or more of these blobs of gray and white protoplasm which, I am pretty sure, are actually syrphid fly larvae.  Although the blobs are stationary when I usually see them, I have occasionally seen one "hightailing" it from one area to another.  Looking on BugGuide.net, this looks like the larva of the syrphid fly, Ocyptamus fuscipennis.  I have certainly noticed syrphid flies that look like these adults hovering around the aphid clusters.  There is no common name for this little fly that I know of, but the BugGuide link will allow you to see what the adult looks like, so that you can notice if your milkweed aphids are attracting attention from this species, too.

Less common, but still easy to find, are these little bumpy caterpillar-like animals that are also, I believe, syrphid fly larvae.  I've not been able to figure out which species or even genus these guys belong to, but I do find it fascinating that two different species of syrphid flies are munching on my oleander aphids!  The only way to really tell for certain would be to raise up some of these larvae to adulthood, which sounds like a fun project when the boys get a little older.

If you ever see a piece of trash seeming to move on your plant, look a little more closely....

You may be seeing a green lacewing larva, which hides under a pile of debris that includes its castoff skins from earlier molts. 

If you look closely in the photo above, you can easily see the yellow oleander aphid being eaten...by the actual lacewing larva at the bottom of the pile of debris.  Lacewings are fierce aphid predators as both larvae and adults.

Not uncommonly among my aphid populations, I will see a dark brown aphid that doesn't move.  This is an aphid mummy.  Tiny parasitic wasps lay an egg in an individual aphid and the developing wasp larva eats out the insides of the aphid, leaving the aphid a literal shell of itself.  Only one baby wasp per aphid, but each female wasp can then go on to lay eggs in many aphids, so aphid mummies are welcome sights on my milkweed plants.

There are other more generalist predators that I'm seeing around my milkweeds, too, which may or may not be preying on the aphids.

I often see tiny, longlegged flies, for example, flying around and landing on milkweed leaves for short periods of time.  Longlegged flies (Family Dolichopodidae) are iridescent green or brown and are known to be predators in both the larval and adult forms.  Although I have never seen one pay attention to, let alone eat, an aphid, I can still hope.  They've got to be eating something!

Clad in the red-orange and black colors of the classic milkweed insect, milkweed assassin bugs (Zelus longipes) are another generalist predator that I see these days, both on milkweeds and on other plants around the yard.  I see the milkweed assassin bugs hunting up and down the plants, sometimes hanging out in the flowers, but just as commonly walking up and down the stems or inspecting both sides of each leaf.  Their eyesight is superb and it can be hard to sneak up on one to take its picture.  At first it will simply duck to the other side of a stem or leaf or flower cluster, but if you persist, it will readily fly away.

The final predator I've been consistently seeing around my milkweeds in recent weeks is a damselfly.  Again, I don't know if this dainty creature is eating winged aphids or not, but I doubt it would turn one down.

So, as you look at the aphids on your milkweeds in horror and dismay, look a little closer - there's a good chance you'll see some other, interesting insects drawn in to the feast that they represent in the animal world!

Monday, July 31, 2017

Elephant Mosquito: The First Mosquito I'm Glad to Find in Our Yard!

It's hard to decide what I love the most:  photographing insects and other animals around my gardens or identifying the insects I see and then learning about how they fit into the patterns of life around me.

Once again I want to sing the praises of BugGuide.net and its community of volunteer entomologists for their help and expertise.

A few days ago I was doing my afternoon walkabout, using my newly "discovered" tripod, and capturing the images of just about any animal I could find.  One of those animals was a fly that looked suspiciously like a very large mosquito, over 1/2" in length.  Thanks to the tripod, I was able to get a reasonable series of photos and look at the little beastie with a more discerning eye.

As I took the photos, one thing I noticed with my "naked eye" was that, as it fed, the insect seemed to be signalling by raising its hind legs, first one side and then the other, showing off a white "bootie" on the end of each leg.

Since the signalling was done slowly and methodically, I was able to capture pictures of it without trouble.  As I looked at the photos, though, I was not a happy camper.  Damn.  Despite all my mental attempts to make this animal into a non-mosquito-type insect, the images revealed that it simply was, indeed, a very large mosquito.  "That's all we need here in the yard," I thought, "an extra large mosquito joining the ranks of the more normal sized, always-seemingly-hungry, stealth mosquito squadron."

However, this mosquito, which appeared to be a female due to its non-feathery antennae, was obviously feeding on the nectar in the mountain mint flowers.  Hmmmm.  Was that normal?

I tried wading through the images of mosquitoes on BugGuide to learn more, but I simply wasn't getting anywhere because I really didn't know what features to focus upon.  So I asked for identification help earlier today.  Within a few hours, I had my answer - and what an answer it is!

My giant mosquito is known as the Elephant Mosquito or Treehole Predatory Mosquito.  In scientific parlance, that's Toxorhynchites rutilus.  As larvae, these mosquitoes are actually predators on other mosquito larvae!  Best of all, the adults feed at flowers, as mine was doing, and the females do not appear to require a blood meal to lay eggs!  I didn't have the slightest clue that predatory mosquitoes existed, so this has really made my night.

What a truly marvelous world we live in!

Friday, July 28, 2017

Red Aphids on Milkweed?

Many years ago I found aphids infesting a little milkweed plant I'd purchased but had yet to plant.  I didn't want to spray chemicals, but I was concerned that the little plant wouldn't make it - and I was concerned that the aphids would spread to all the other plants in my garden.  Feeling very noble and "green", I hooked up a strong sprayer to the hose and simply, carefully, sprayed all those little yellow aphids off the plant.  Ah, I'd saved it!

Except that when I got to looking at the milkweed plant after I'd washed the aphids off, I noticed a lacewing egg on its willowy stalk.  I'd washed off all the food that the lacewing mother had planned for her offspring to eat and thus I'd managed to kill the beneficial-predator-to-be.


Note:  The photo above is of a lacewing egg, but on a tree leaf, rather than on a milkweed.  The egg on the tip of the stalk is diagnostic, as far as I know, of a lacewing egg.  Sadly, I don't appear to have photographed my little milkweed/aphid/hose experiment, but I thought you might be interested in what a lacewing egg looks like.

Back to the story.....   Feeling a little sick at heart after spraying off the aphids and finding the lacewing egg, I took to the web to do some research.  WHY didn't I do that research BEFORE I reached for the hose sprayer?

It turns out that most aphids are pretty species specific regarding their host plants.  The little yellow aphids with black legs on milkweed are oleander aphids (Aphis nerii) and are found primarily on milkweeds and oleanders.  These little aphids were never going to be a problem on my asters or Echinacea or garden vegetables. 

Interestingly, oleander aphids are not native to North America.  They were brought here along with oleanders, which are also not native.  Luckily, unlike with many other non-native insects like Japanese beetles, there ARE predators and parasites that will help keep oleander aphid populations under control.


In this photo, for example, it's easy to see both the yellow oleander aphids and the aphid-eating syrphid fly larvae on the tropical milkweed.  The syrphid fly larvae are some of the predators on oleander aphids.



Fast forward to recent days.


Evidently, with so many more people planting milkweed for monarchs these days, a lot of folks are suddenly noticing oleander aphids on their milkweeds.  Questions abound about how to kill these aphids without jeopardizing the monarch caterpillars.

In my experience, thanks to the work of predatory insects, the populations of oleander aphids on milkweeds will cycle up and down, but will almost never hurt the plant.  Since I think chemical alternatives do far more harm than any possible good, I freely share my experiences whenever it seems appropriate.

In the above photo, for example, there are at least two aphid mummies and two syrphid fly larvae among the aphids. 

The aphid mummies (round, dark brown remains of aphids) are what happens when small wasps parasitize the aphids.  Each aphid mummy produces one new adult wasp.

The syrphid fly larvae feed exclusively on aphids and look like moist bird droppings to me.  You can also see the out-of-focus, brown ball of another aphid mummy in the upper left hand corner of this closeup, too.

Going back to the original photo above, here is a closeup of the second syrphid fly larva in the upper left corner.  This looks like a different species of syrphid fly larva to me.

Yellow colored, oleander aphids are the only kinds of aphids I've ever noticed on milkweeds, so imagine my surprise the other morning when I went out and found a cluster of what looked suspiciously like bright red aphids on one of the flower clusters.  What in the world?!  I couldn't help but think of Sheldon Cooper when he exclaims, "Oh, what fresh hell is this?!"

After photographing my unusual "red aphids", I realized they were actually newly hatched nymphs of the large milkweed bugs (Oncopeltus fasciatus) that I've been seeing on my milkweed plants in recent weeks, regularly having x-rated fun.  It surprised me a little bit, as I was under the impression that large milkweed bug nymphs primarily eat milkweed seeds and these were on flower bud clusters.  However, insects don't read instructions on what they are supposed to do, as we all learn daily.

Now I'm curious to see if I can tell what predators will show up to help thin the ranks of the young large milkweed bugs.  How could anyone ever be bored in a garden?!

Monday, April 03, 2017

The Sap is Rising...and the Sapsuckers Are Visiting

Three days ago I noticed a pair of woodpeckers fly over to one of our pignut hickories (Carya glabra).  These deciduous trees are always late to leaf out, waiting until the azaleas are basically done blooming, most of the spring bulbs are finished, and the laurel oaks (Quercus laurifolia) have lost their old leaves and regained fresh, new ones.

We have 3 reasonably good sized pignut hickories in our backyard.  As a group, they are a great advertisement for the benefit of open-pollinated, seed grown trees:  none of the three does anything at exactly the same time as the other two.  These three trees leaf out at different times, develop fall color at different times, and drop their leaves at different times.  For a while I even began to wonder if they were actually three different species!

The big, terminal buds of the tree that the woodpeckers chose this weekend are swelling and just starting to break open.  The other two "sibling" hickories are still quiescent.  I'm not sure I would have noticed the changes in this tree if the woodpeckers hadn't shown up....

But show up they did - and they put on quite the show for several hours.  My first, fleeting impression was that this wasn't a pair of red-bellied woodpeckers, which are our common species here.  I've also seen downy woodpeckers and northern flickers in the yard, but this pair was obviously too big to be the former, too small to be the latter, and too "blandly colored" to be either of those species anyway.

So I got my binoculars and took a closer look.  A pair of yellow-bellied sapsuckers!

At first I thought the two were mating.  They would climb up the tree trunk almost in tandem for a while, then one would jump the other and they would tumble head over heels, dropping from 10 to 30 feet, hitting branches as they dropped.  Eventually they'd disentangle, right themselves on the trunk, and start climbing up again.  This went on over and over again, for several hours.  I presume they took breaks from their acrobatics, but I wasn't able to watch the entire time, so I don't know for sure.

Finally, in the early afternoon, the male flew away and I haven't seen him again.  The female remained on the tree, though, and was there again all day Sunday, busily tapping away on the trunk.

I don't have any photos of the pair, as I didn't want to interrupt their "dance" by getting too close.  I was able to get some photos of the female on Sunday as she worked on digging her sap wells and I worked on weeding the garden bed nearby.

I've since decided that this pair was probably fighting over food, not mating.  Yellow-bellied sapsuckers don't nest here - their breeding range is much farther north.  I don't think they'd actually be copulating this far south, long before they've completed their spring migration and found a breeding territory, let alone constructed a nest.  I think the sap is rising in this individual tree, based on the swelling buds, and these two birds were simply fighting over whose "territory" it was going to be while that was going on.   They just happened to be a male and a female.

Now it's going to be interesting to see if any sapsuckers stay around to feed on one of the other two hickories in the yard, as their sap starts to rise and their leaves unfurl later in the spring.

How can anyone get bored in a wildlife garden?!

Sunday, April 02, 2017

Using It Up - Common Buckeye Caterpillars

In early spring, lawns around here sprout a pretty little native wildflower known as old field toadflax (Nuttullanthus canadensis).  An annual, it is here and gone almost before you realize it, but it is considered a "lawn weed" and, as such, it is not considered desirable by most homeowners.

I find this dainty little flower enchanting.

Old field toadflax is related to snapdragons, which you can see in the shape of the bloom...if you take the time to look closely at it before you mow it down.  Perched on the ends of long, slender stems, the tiny blossoms would really have to occur in huge numbers to make a show of any sort, but my "selective wildflower vision" zeroes in on them and magnifies their attractiveness to enjoyable size.

Given my propensity to enjoy what shows up without any effort on my part, I've let the toadflax grow where they appeared in my front flowerbeds, rather than weeding them out with the oak seedlings and dewberry.

When I went out to do my occasional bed weedout on Saturday morning, I noted that the toadflax were done blooming and I thought that perhaps it was time to pull them out to "neaten up" the bed.  On the other hand, if I let them remain a bit longer, I could more reliably count on new plants next spring....

As I was weeding and debating this weighty question with myself, I noticed a black caterpillar on the ground near one of the plants.  Hmmmm.  Another, larger caterpillar was on a nearby plant.  Looking a bit further, I noticed a third caterpillar munching away....

By the time I looked at all the plants, I'd found 7 caterpillars! 

They were all the same species and they were all either on or right beside the old field toadflax.

Looking at the flower spikes, I noticed that the lower flowers had set seed, dried and were releasing seed.  The remains of the upper blooms were still green, but obviously seed was forming.  Since these are annual plants, as soon as all the seed is set, the plants will basically dry up and wither away.

When I went inside and looked up the caterpillars in my handy-dandy caterpillar guide, I decided that these were probably common buckeye cats (Junonia coenia), a highly variable species of (butterfly) caterpillar that is known to feed on plants in the snapdragon family, including toadflax.

This discovery lifted up my spirits all weekend long.  Isn't nature simply amazing?!  This relatively small annual plant blooms, sets seed, and then dies.  Rather than waste all that great plant material by simply having it dry up and blow away, Mother Nature arranges to have mama buckeye butterfly stop by and leave a couple eggs.  The eggs hatch into tiny caterpillars who, just as the plant is finishing with the foliage, eat up all the leaves and change the plant material into butterflies.

Beauty in flower form turns into beauty in butterfly form.  I call that pretty amazing.