Wednesday, August 25, 2021

Hummingbird Moths and Other Hawkmoths

Snowberry clearwing moth - REK

These hummingbird moths are a common sight around a flower garden this time of year.  People love to see them hover, slurping up nectar through their long proboscis as they flit between blossoms.  We have two hummingbird moth (HM) species, snowberry clearwings (Hemaris diffinis) and hummingbird clearwings (Hemaris thysbe).  Their ranges overlap in Missouri as seen here.

Clearwing at rest - REK

We heard from several friends the last week, concerned that when they are finding large green hornworm caterpillars that these are HM babies eating their tomato plants.  These moths are not the same species although they are relatives.  There are many web sites that add to the confusion by calling hawk moth caterpillars by an alternate common name of hummingbird moth, demonstrating the importance of scientific names.

H. diffinis on tubular flower - J. Motto

Our friendly HM feed in daylight hours although they may stay out for a late supper if they find a great menu. They are especially adapted to sip from tubular flowers, just like a hummingbird.  Their larvae feed on honeysuckle family members - buckbrush, snowberry, horse gentian, Lonicera spp and dogbane including Amsonia (blue star). H. thysbe cats also eat viburnum, hawthorns, cherry and plum.

Snowberry clearwing hornworm caterpillar

Their larvae are equipped with a horn on the end, thus a"hornworm."  This is another cause of confusion as the hated tomato and tobacco hornworms that decimate tomato plants are similar although much larger.

Tobacco hornworm

Tobacco and tomato?  How can that be a common food plant between these hawkmoth larvae?  Science Daily sheds some insight.

"The Solanaceae is a family of flowering plants, many of which are edible, while others are considered poisonous.  The family is informally known as the nightshade or potato family. The family includes the Datura or Jimson weed, eggplant, mandrake, deadly nightshade or belladonna, capsicum (paprika, chile pepper), potato, tobacco, tomato, and petunia.

The Solanaceae are known for possessing a diverse range of alkaloidal glucosides, or simply alkaloids.  As far as humans are concerned, these alkaloids can be desirable, toxic, or both, though they presumably evolved because they reduced the tendency of animals to eat the plants."

Manduca sexta - Lyle Buss UFL

The tobacco and tomato hornworms hawkmoths are in the genus Manducae.  Unfortunately they are called hummingbird moths in some references.  They can hover like a hummingbird but they are mainly crepuscular, flying primarily at sunset and sunrise. 

A frequent question a naturalist hears are "what good are fill in the blank?"  Even mosquito larvae feed a number of aquatic species.  In this case, you can take comfort in this long answer from the Featured creatures of

"Tobacco hornworms have several natural enemies, including vertebrate species that feed on caterpillars, such as birds and small mammals, and insects like lacewing and lady beetle larvae that consume the eggs and early instar larvae. Wasps are a common predator of hornworms. Paper wasps and other insects that provision prey for their young will take hornworms from the host plant, paralyze them, and place them into the nest cells containing the wasp’s eggs as a future food source. 

Parasitoid wasps, like Cotesia congregata, use hornworms as a food source for their developing young. These wasps deposit their eggs inside the hornworm’s body and the larval wasps develop within the caterpillar, feeding on it as they progress through their life cycle. When pupation takes place, the immature wasps spin small, white, silken cocoons that protrude from the body of the still-living caterpillar. The cocoon-covered hornworms are a sight of great interest in the garden, and many fear that the parasitized caterpillars will have a negative impact on their garden. In fact, the opposite is true because the hornworm will eventually die and several adult wasps will emerge, mate, and seek out additional hornworm hosts for their eggs."

Revenge of a parasitoid wasp - REK

So fear not, defend your tomato plants with a clear conscious.

Saturday, August 21, 2021

Cicada Emerging

Not an Alien  -  Frank Johnson

There are two predictable events in August, cicada appearance and the emergence of their photographers.  Frank Johnson started this year's cycle with his dramatic photograph above of cicada eclosing, looking like it came out of a space movie.  Most species are green the first few hours, darkening as the air dry their wings and bodies.

Next Su Lyn Rogers sent me this beauty.  When she initially found it on a 10 PM dog walk, it was a newly-emerged cicada crawling on the sidewalk. She says:

"Under the porch light, I could see that it was still wearing some of the soil from its underground stage that had lasted for at least two years. I recorded some videos, then left it outside on a birdhouse on my bench intending to check on its progress later."

She sent this video as it crawled around, looking for a place to eclose.

Freshly eclosed  - Su Lyn Rogers

When she returned later it had completed molting.  MDC Discover Nature has descriptions of the different annual species which we can't identify with this fresh specimen until it dries out.

These are called annual cicada as they appear every August and September, unlike the 13 and 17 year periodic cicada which get all the glory in the press.  This however is deceiving as the life cycle of an individual is over two to five years.  

Also known as "dog day cicadas" they are members of the genus Tibicen, named for their abundance in late August through September in the hottest times.  They make a buzzing sound when they take off on short flights when disturbed and create a loud grating sound when held.  Only the males sing and each species has a distinctive sound, giving them names like "buzz saw" and "scissor grinder" which you can hear at this link.
Like their periodic cousins, they lay their eggs on twigs and the larvae emerge, leap off into space and land on the ground where they dig in.  They then burrow into roots to suck sap for the next few years until they mature and emerge, crawling up a tree or post and hanging on tight while the adult emerges and flies off, leaving the empty shell of dried skin to puzzle or delight a lucky child.  These cicada appear to be annual because each year some are emerging and mating.
Cicada Killer - Larry Wegmann
They are soft and juicy when they first emerge, hardening over 30 minutes.  As they hang on trees they are vulnerable to a specialized predator, the cicada killer wasps.  This is Sphecius specious, the largest wasp in North America.  Although fearsome in appearance, it saves its sting for a cicada to haul off to feed its young as described
in this past blog.  The female can carry a cicada twice its size!

Copperhead fast food - Charlton McDaniel in Tulsa World
Cicada's also face another predator, copperhead snakes.  They will climb trees to find these tasty morsels.  This blog has more information and these incredible photos like the one above from the Tulsa World  are worth a visit.

Wednesday, August 18, 2021

Jagged Ambush Bug

Ben Caruthers shared this picture with me and I was hooked. So was he as he continued the pursuit of this extraterrestrial bug which is always perched on a flower head, preferably a yellow or white blossom.  I will let him tell the story of this incredible set of his photos.


"I captured photos of some Rose Pink flowers on July 21. When I went back to edit the photos on August 9, I noticed a funny white blotch on one of the flowers. A closer look revealed a white color morph of a Jagged Ambush Bug! By the time I discovered the insect in the photo the flowers had already mostly wilted. A visit back to the flowers and general area did not reveal the ambush bug. From there forward I started paying more attention to the details of each flower photo in case I had another sighting similar to this one.

On September 19 I noticed a lot of insect activity on the New England Aster in my front yard. I waited for some good lighting and decided to try to collect some images of the participants. In that group of insects I spotted another Jagged Ambush Bug! This one displayed a more typical color pattern than the white one earlier. I collected several photos of that one example. I did not capture the insect, but I plucked the bloom that it was on and rotated it to get all angles. Then I placed the bloom next to another to allow it to move to a fresh bloom still attached to the main plant.

After thinking about it overnight I thought if there was one, maybe there would be more. I went back out again on September 20 and found two more on the same aster flowers. I took a few photos of those two with as little disturbance as possible. I also found the ambush bug from the previous day, but it had died upon the flower where I left it. 

Other naturalists on iNaturalist identified the insect on the aster as Phymata fasciata, a member of the ambush bug family Reduviidae. Ambush Bugs sit motionless on flowers, waiting to clutch other insects with their hooked front legs. Tiny and well camouflaged, they often take prey larger than themselves, including bees and large flies. Apparently the bugs I was watching weren’t hungry. I watched several bees and flies land on top of them and the ambush bug did not even flinch."

P. fasciata is a member of the Phymatinae family, called Jagged Ambush Bugs (JAB).  Their camouflage is incredible, allowing them to perch on a flower head undetected by a flower fly or bee which lands beside them.  Their powerful forelegs grasp the prey and they stab them with a beak that injects digestive juices into the insect, using what is essentially an external stomach until they suck up the goodies.

"They share many traits with assassin bugs but can be separated by their hooked forelegs with greatly widened femur sections; clubbed antennae; and widened back portion of the abdomen (so wide that it usually extends outward beyond what the folded wings cover). Most species have jagged body contours, disrupting the outlines of their bodies against the textured background of flower heads.  MDC Field Guide"

You can see Ambush Bugs in action in this Youtube video.  Then see this video where the bug is digesting a bee at least ten times its weight.

Lots of insects are called "bugs" but JAB is a legitimate member of the true bug order Hemiptera.  In this photo you can see the defining characteristic of Hemiptera, literally "half-wing."  Their forewings have two different textures—the proximal half (closest to the body) is leathery, and the distal half (away from the body) is membranous, like a fly’s wing as seen in this photo.  They have incomplete metamorphosis, meaning that the young look like wingless versions of the adult.


This is my favorite photograph.  The JAB appears to be focused on an innocent flower fly which doesn't recognize the danger.  The focus is deceiving as their eyes are compound and the black spot isn't a pupil.  

More importantly, the "JAB" is actually JABs if you look closely at the closeup crop on the right.  That is a mating pair.  I suspect if the fly got closer the male on top would leave for a post-coital snack.

Assassin bugs come in a wide variety of colors but most start off life as pale nymphs like this one from Gala Keller.  They go through incomplete metamorphosis so the nymphs resemble the adults but without wings.

Update September 1, 2021

My sharp eyed assistant Vivian brought over this fresh specimen below on a withering flower head which posed obligingly on my forceps.

The MDC webpage has a good summary on assassin bugs.  Click to enlarge.

Saturday, August 14, 2021

Predatory Stink Bug Eggs

We had a new neighbor Cyrus in 2018, who is on the lookout for nature.  His toddler daughter was excited to release the spicebush swallowtails that were emerging from chrysalises we had given him, and the whole family has been nurturing her interests in the natural world.  He shared with us a leaf from a newly planted spicebush that had some tiny bumps.  A macro photograph revealed the hidden beauty of insect eggs.

Eggs with a ballpoint pen - REK
The eggs were roughly 1 mm in diameter with a crown of spikes, with long projections around the top that are quite distinctive.  They were diagnostic of Podisus spp. of predatory stink bugsThe most common species in our area is Podisus maculiventris, the spined soldier bug (SSB).

Spined soldier bug -
SSB are generalist predators, attacking over 90 species of insects.  For that reason they have been introduced to many other countries as a biological control agent (BCA) for agricultural pests.  They are considered beneficial although monarchs might disagree.  For some reason they are attracted to butterfly milkweed where they will attack the occasional innocent monarch caterpillar.

First instar -
I saved the eggs expecting to hatch a cluster of brightly colored larvae to photograph.  They go through five colorful instars, each with its own distinctive pattern before becoming very boring brown adults, all shown here at Entemdept.ufl.  Two weeks later I found tiny specks on the bottom of the bug box.  The hatchlings weren't the little bright red 1mm SSBs I expected.  Instead they were tiny chalcid wasps, parasitoids that had been living in the eggs, protected and fed by their unwitting hosts.

Chalcid wasps are hymenoptera, related to other wasps, bees and ants. They are in the superfamily Chalcidoidea with 22,500 known species worldwide that are constantly undergoing taxonomic debates so I didn't try to identify them further.  Many species have been imported as a biological control agent (BCA) to control plant pests.  In this case a BCA attacking another BCA.

These wasps were the product of smaller eggs carefully placed on the 1mm SSB eggs.  I am constantly amazed at how much life is out there that we never notice.  Here was a complete food cycle flying under the radar until exposed by a fellow nature nerd's curiosity about bumps on a leaf. 

Now 8-12-2021

I  saw a smudge on our storm door glass turned out to be SSB eggs.  Two days later they hatched and were crawling about, probably discussing where to find a juicy caterpillar for breakfast.  You can see them here crawling around a 2" section of window.

They have a tenacious grip on smooth surfaces.  I had to pry them off one at a time from the glass and again from the plastic bug box to release them in the garden.   Please don't ask me why.

Tuesday, August 10, 2021

Owlfly Eggs

Stinkbug eggs - REK

Tonya Smith sent me these pictures of owlfly eggs she found on her fennel.  Their barrel shape resembles stinkbug eggs which would have been my first guess but those are usually found in a cluster on the underside of leaves.  I sent the picture to INaturalist and owlfly eggs didn't come in the top 10 suggestions.  

Owlflies are in the family Ascalaphidae.  The insect order Neuroptera, or net-winged insects, which includes the lacewings, mantidflies, antlions, and their relatives.  The vast majority of these are predators, consuming aphids and other species we consider pests.

Owlfly- Wikipedia
Adults resemble dragonflies except they have long clubbed antennae.  They tend to be rapid flying crepuscular hunters, and frequently are seen around porches and decks where they feast on other insects attracted to the lights.  When landing on a branch they hold their abdomen up at an angle, resembling a twig.  You can see the "net-wing" pattern in this photograph.

First instar larvae before dispersing -  Marita Beneke-Wikipedia
Graham Montgomery

Their larvae are also predators of many plant eating insects.  If you think the picture above bugs you, imagine the effect on a mother aphid in the neighborhood.  Notice the distinct head and a pair of huge caliper-like mandibles that are usually held wide open.  MDC's Discover Nature has this description of their life cycle.

"Female owlflies lay eggs in a line on twigs or plant stems. In addition to rounded, fertile eggs, she also lays a batch of smaller, “trophic” eggs nearby. These won’t hatch. They serve as a first meal for her hungry hatchlings and may prevent them from eating each other. They’re sticky and whorl around the stem like a fence, so they might also keep away ants or other predators. The young larvae move to the ground, where they hunt, eat, grow, and molt. They pupate, in a silky cocoon, in leaf litter."

Friday, August 6, 2021

Leopard Slug

This story is from Alee Huerta who has returned to the MN fold after an absence while pursuing her education.

This past weekend we had a Leopard Slug crawl across our porch. My 1st thought was to grab the salt... and I did.  But as my 7 year old buddy and I plopped down with the salt, my inner Naturalist was like.... "hold up."  I'm glad I took the time for education because I found out that these slugs don't actually destroy living plants, a common misconception.  Leopard Slugs (Limax maximus) eat fungi, rotting plants and even other slugs. They need to keep their bodies damp in order to breathe, so are usually found in dark, damp places, particularly among rotting logs.
Sex on a string -Bairds

All slugs are hermaphrodites, meaning that each slug has both male and female sexual organs. They still need to mate with another individual though and LS have quite a spectacular way of doing this. The two slugs climb a tree or other structure, then produce a thick strand of mucus that they hang from on a branch.  This is partially because their penis which will exchange their sperm is so large that it requires gravity to distend it, actually causing their body to shrivel up some from loss of fluid. intertwined with one another.   These sex organs protrude from their heads and intertwine to exchange sperm, the pink packet on the left.  You can see all the action as filmed here by our MN, Michael Baird.   

As we say in the WOLF School, "here is another fun fact."  Once they have completed copulation, one or both will eat their way up the mucus strand, retrieving the energy stored in it. This and other fun facts are more colorfully described in this story from Wired.

Editor's note:  This is a family blog but we will recommend this graphic BBC video as it is narrated by the very proper Richard Attenborough.

After mating, each slug lays clutches of transparent, round eggs in damp places.  As slug babies, they are a primary food source for lightning bugs! I love lightning bugs, so the way I see it, to love any one certain thing you need to respect everything that one certain thing needs.  They reach sexual maturity in 2 years and can live for 3 years.

Limax maximus, literally biggest slug, originally were native to Europe and Mediterranean countries of Africa and were first found in Philadelphia in 1867.  In spite of their top speed of 6" per minute they really get around and are now found around the globe! They are almost always found near human habitation — usually in lawns, gardens, cellars, outbuildings or in other damp areas.

LS is generally a nocturnal slug that feeds mostly on rotting plant matter and fungi as well as other slugs. In Texas and Oregon it can sometimes be a pest of gardens, greenhouses, cellars, and mushroom beds.  On the other hand, by eating dead and rotting plants, as well as fungi, Leopard Slugs recycle nutrients and fertilize the soil.
Our LS like many other slug species have a small disc of shell inside their body. Slugs evolved from snails and this disc is a remnant of what used to be the snail’s shell.  They can come in a wide range of shades although these leopards never change their spots.

Finally, research by Christie Sahley and colleagues have demonstrated associative learning in LS by aversion therapy.  Carrot and potato juice normally attracts them.  After they have been exposed to them flavored with an additional bitter dose of quinine sulfate, these attractants subsequently lose their gustatory charm.  Yes, it appears you can teach old slugs new tricks.
Dr. Chris Barnhart and MDC have published Land Snails and Slugs of Missouri, available in many different formats at this Archive link.  You can download it as a PDF or Kindle document.