BugGuide for the Win!

A big thank you and shout out to the folks at BugGuide.net for their help in identifying so many of the little beasties that I see in my yard and gardens! 

Last week was a perfect case in point.  I saw a large black bee nectaring on swamp milkweed from my kitchen window and I grabbed the camera to get a few photographs.  This insect was new to me,  but it reminded me of a bee that had been recently talked about and shared in a Facebook group about pollinators.  So I looked up the two-spotted longhorned bee, the species in question, and it looked good...but maybe just a little different from what I was seeing. 

The abdominal spots were smaller in my individual than in many of the photos of the two-spotted longhorned bee in BugGuide and the long hairs on the legs of my individual were dark, not light, but otherwise it looked like a reasonably good match.  There are really a limited number of large black bees it could have been, excluding bumble bees, which this wasn't.  So I tentatively identified my photos and submitted them as an ID request.

Within a day, Dr. John Ascher had identified my specimen as a southern carpenter bee (Xylocopa micans), a species that I was totally unfamiliar with and had never even considered. I actually thought that the eastern carpenter bee (Xylocopa virginica) was the only large carpenter bee in our area so I hadn't thought to look more closely at carpenter bees.

According to the brief research I did, there is not much known about the life cycle of the southern carpenter bee.  A fact sheet from the University of Florida reports that the only nests that have been reported were in small branches of Ligustrum (1958) and red maple (1975), about 1-1.5 m above the ground.  Apparently this species is NOT an economic problem, as the eastern carpenter bee can be.

Was this an earth shattering identification?  No.  But the only other way I know to really identify many of the insects I photograph, including this one, would be to catch them and kill them, then look at them under magnification, using keys.  While that is certainly the classic way to deal with insect identification, I am gardening on less than 0.4 acre in the middle of a suburban development where new assaults seem to occur daily against the wildlife present.  Trees and shrubs are cut down and replaced with chemical-soaked lawn.  What flowers there are come from the big box stores which, around here, means they are full of neonic pesticides.  There are far more non-native plants than natives in everyone's yards, providing little food for native insects and other animals.  Often I only see one individual of a species in my yard - and, if I collected it to identify it, I might have just kept that species from keeping a toehold around here.  For example, I have not, to my knowledge, seen a southern carpenter bee here in the 3 years we've lived here - and I haven't seen another one since I saw this individual a week ago.

Why do I find it so important to know what the various insects are in my yard and gardens?  I ask myself that question on a pretty regular basis, wondering if I'm wasting everyone's time, including my own.  Then I identify a new species and learn about it, finding out that I have...

... a wasp species (Prionyx parkeri) that controls short-horned grasshopper populations and pollinates flowers...

... or a fly species, tiger bee fly (Xenox tigrinus), that parasitizes carpenter bees and balances their populations...

... or yet another syrphid fly whose larvae eats aphids.  (The syrphid fly larva is the large, brown and white blob on the milkweed stem, surrounded by its food, oleander aphids.)

The complex web of relationships in even my basic little gardens truly astounds me, and I learn so much by identifying the different species and researching a bit about their life cycles and feeding habits.   I try to share that information with others, too, hoping to encourage fellow gardeners to just relax and let Mother Nature keep the balance in their yards instead of pulling out the poisons to "keep everything under control".

In fact, thanks in great part to the insect identification help I've received from BugGuide, I've come to think that human "control" is highly over-rated and much more likely to do harm than good, especially in a garden.  What insects are YOU seeing in your garden, and what are you learning about the balance of nature all around you?  Have you dared to go chemical free yet?

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?!

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!

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?!

The Milkweed Community Beyond Monarchs

My attempt to rescue 4 monarch caterpillars that were about to eat out their food source seemed to fail, despite my provisioning them with 6 white milkweed and 2 swamp milkweed plants from 7 Pines Native Plant Nursery.  The last - and largest - of the caterpillars curled up in a question mark on the soil surface one day and then disappeared overnight.  Eaten?  Probably.  Pupated somewhere?  Possibly.  At any rate, I have no more monarch caterpillars to watch right now.

However, I do have my 8 milkweed plants.  Making me quite sure that these plants weren't being treated with neonics, my milkweeds came pre-supplied with bright yellow aphids.  A little research on BugGuide.net informed me that these aphids are oleander aphids, Aphis nerii.  Oleander aphids are actually native to the Mediterranean area, but they have become common around the globe, having traveled everywhere on oleander plants.  Oleander aphids are especially common on oleander and on milkweed plants, although they are known to feed on several other types of plants as well.

As I was looking for the monarch caterpillars, I noticed a fly hovering about 6" from the milkweed plants. Watching more closely, I noticed there were actually about 6 flies, and that occasionally one would dart in, look like it was depositing something, and return to hovering.

So I got my camera and tried to take a photo.  After a long time - and many attempts - I hadn't managed to get a nicely clear photo, but I had managed to get a couple shots where I was able to at least get a feel for the flies I was seeing.

Between the blurry photos, the gestalt I had, and the research I did, I think that this little fly is a species of syrphid fly, Ocyptamus fuscipennis, known both for its dark colored wings and its diet of aphids in the larval stage.  That's just my best guess, however.  It's not a verified identification.

As I was trying, again and again, to get a clear photo of one of the syrphid flies, I suddenly noticed a couple tiny, tiny wasps walking among the aphids.  As I looked through the camera lens, I watched one of the wasps curl its abdomen and seem to poke the aphids individually.  This was a little odd, because the wasp curled its abdomen relatively far away from the aphids, but I was sure that it was laying eggs on them.  Again I took photos, but again I didn't get any good shots - to get clear photos of such minuscule insects, I needed a tripod for stability and a windless day with no sway in the plant stems.

Despite my lack of good photos, I saw enough to have a good idea of what was going on.  After more research, I suspect that the small wasps were braconid wasps, which parasitize aphids by inserting an egg in an individual aphid.  The egg hatches and the larval wasp eats the aphid from the inside, killing the aphid and leaving an "aphid mummy", which is essentially the shell of the aphid with the larva, then pupa, of the wasp inside.  When the wasp emerges from its pupal stage, it cuts a hole in the aphid mummy and emerges, to repeat the cycle.  If you click on the link I've highlighted, you'll see a great photo posted on BugGuide.net of one of these wasps in egg-laying stance, ready to lay an egg on an oleander aphid.

Note:  Looking at several of my photos from this series, there are many little dots on them.  The dots were only visible when I enlarged the images and they only occurred in the middle of the milkweed plants.  I don't think it was a dirty lens (although I will certainly be cleaning it to verify).  There is also a small, beetle-like insect on the vein of the milkweed leaf in the very bottom right of the photo above, which I haven't identified.  I think it might be some sort of weevil, but that is simply another guess.

So right now, with no milkweed blooms to be had, I've already got 4 species that are relying on my milkweeds for the basis of their life cycle:  monarchs, oleander aphids, a syrphid fly, and a braconid wasp.  I've also seen examples of herbivory (monarch caterpillars and oleander aphids), predator-prey relationships (syrphid flies and aphids), and parasitism (braconid wasps and aphids).  Pretty cool for February!