Thursday, October 18, 2018

Predatory Stink Bug Eggs


We have a new neighbor, Cyrus, 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 - Entnemdept.ufl.edu
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 - entnemdept.ufl.edu
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.

Monday, October 15, 2018

Wee Tiny Ladybug


 
I picked a little fleck off my pant leg and it crawled up onto my thumb for a picture.  It looked like a lady beetle but it seemed too small.  Through the wonders of INaturalist, it came up as the number one choice, a twenty-spotted lady beetle (TLB) Psyllobora vigintimaculata.  Another common name is "wee tiny ladybug."  At 2-3mm long, I thought they would rarely be "spotted" (sorry!) but I found 9 pages of their photographs on Bugguide.

 
Psyllobora sp. are called fungus-eating lady beetles.  P. vigintimaculata (Latin for twenty spotted) feeds on powdery mildew that occurs on leaves from ground level to tree tops. They scrape up fungal spores with mandibles armed with rake-like rows of small teeth.

"Fungi, we have lift-off!"  Oliver Burris CC
TLB are found in all states including Alaska and the the first specimen to be described was in Missouri!  They come in a variety of colors with a white to tan background.  The color can be variable, based partially on the region they are found in, but they all have in common placement of their spots.

Like all "ladybugs" they are beetles in the family Coccinellidae.  The majority of this family feed on plant eating insects that are unpopular with gardeners such as aphids and scale insects.  Although we think of them crawling around they are capable of flight after lifting their heavy wing covers.

Ten years ago identifying species like this required an extensive knowledge of entomology and would be left to the species specialists or an extensive search of old reference books.  Now sites with photo recognition such as INaturalist.org allow quick comparisons and expert entomologists share their time identifying photographs on Bugguide.  What a great time to become a nature nerd!

Saturday, October 13, 2018

Tiny Oak Galls

Zopheroteras guttatum with a ballpoint pen




Collecting pin oak, Quercus palustris, leaves for a school project, I felt a tiny hard bump on one. Under magnification it was a perfectly spherical 2mm gall that looked like a piece of candy.  The usual sources couldn't identify it, but I got a rapid response from a submission to Bugguide.  This is a gall of a cynipid wasp, Zopheroteras guttatum.




Zopheroteras guttatum - eol.org
Galls catch our eye with lots of pictures but the insects that build them get little respect.  In this case I did come up with pictures of a Z. guttatum adult from the Smithsonian on Eol.org.  Three pages of Google searches yielded only other photographs of galls, most of which were confirmed by Charley Eisman, the guru of galls.  




Eisman's describes  Z. guttatum galls in more detail.  "Causes spherical, 1.45-2.5 mm galls, with purple spots, single on a secondary vein on underside of Quercus palustris, imbricaria,
or texana leaf, in fall."  Initial descriptions
specified the underside of the leaf but there are
now other examples of the same galls on the
upper side.




I went back to the tree looking for more of these galls but found only other leaf galls.  These fuzzy oak leaf galls are far more common, produced by Callirhytis furva They are said to drop from the leaves in October but I more commonly find them attached to a fallen dried leaf on the ground.  Again, EOL provided a photo of the cynipid wasp that makes the gall.





Callirhytis furva - Eol.org CC
I haven't had any success in raising the wasp from a gall but I may have given up too soon.  Weld who wrote the book says they emerge "in the second or third spring in late March."  Typically a cynipid wasp would mate and then lay eggs on a leaf, in these cases a red oak.  The mere fact that these 2-3mm wasps would find each other to mate after a 3 year gestation is hard to fathom but "love finds a way,"






Like the spiny oak galls
Hard dried galls - REK
we wrote about in the past, the hatchling that emerges from the egg creates damage on the leaf which responds by growing around it, creating a shelter and food source until it is ready to emerge.  What I find fascinating is the many different ways that the leaf responds, each distinctive for the specific species.  I found a few other less distinctive galls on Cyrus's pin oak,  including one below that had delivered its young.
Empty gall - REK
Each of these galls are now in clear plastic boxes, trying my wife's patience as they fill the closet.  I know she will be excited to know that I now need to keep them for three years.

Thursday, October 11, 2018

Hammerhead "Slug"

Worm measuring over 3 WGPBC units
Our friend Pat found this while walking her dog.  It left a slime trail in the morning light and she had the forethought to photograph it with her friend Erin's snack pack for a size comparison.  Converting WGPBC units, (Whole Grain Peanut Butter Crackers) to inches (5.2") we can say the critter is over 7.3" long!

Her story is a great example of how an untrained naturalist approached the unknown.
"It almost looked like a small snake with a dark stripe down center back and lighter stripes on either side of that. It had a ginkgo leaf shaped ‘head’ and seemed to be de-scaling the curb like a snail as it crept along. It also moved differently than your standard worm.  When we looped by the area again on our walk the live one had its tail smashed and succumbed to its injury. I did collect the dried out dead specimen, don’t ask me why.
I saw another one a few days later that was at least 12 inches long, and the flat half-moon ‘head’ was proportionally larger as well.  After the sightings last week I Googled ‘worm-like slug’ and got an immediate hit on Hammerhead Slug.   The site I viewed did not describe them as being in this area, but it sure looked like what I was seeing."

The Hammerhead Slug, aka. Greenhouse Planarian (Bipalium kewense, BK) is the "Worlds Largest Flatworm" and one of the few flatworm species that live on land.  It is unrelated to slugs which are in a totally different phylum, but it leaves a slime trail like slugs and snails do.  It was probably originally an Asian species that has been imported along with potted plants.  It occurs throughout the southern US as well as world wide.  Pat's is the first one reported in Missouri on Inaturalist.org.
Bipalium kewense capturing an earthworm  -Pierre Gros
Here is a description of the feeding process.
"The flatworm initiates here the process of ‘capping’ the anterior end of the earthworm. Observed reactions of the prey suggest that it is at this stage that the planarian secretes a toxin to reduce prey mobility. The planarian also produces secretions from its headplate and body that adhere it to the prey, despite often sudden violent movements of the latter during this stage of capture. Pierre Gros.
Posterior fragment
Although all Bipalium sp.  are hemaphroditic, their usual reproduction is by asexual fragmentation.  They attach their tail to the ground, then pull it off to leave the segment to move on its own.  Over the next few weeks it regenerates a head and pharynx and becomes a fully functional if somewhat shortened adult.  Fun fact in bad taste: Its pharynx is also its anus!

BK feeds primarily on earthworms which it tracks down, then pins down by its slime.   It also produces a neurotoxin (tetrodotoxin) that results in paralysis that may help it mobilize the worm.  Dinner spoiler alert!  Then its pharynx spreads out and releases an enzyme that partially digests the worm outside its body.  Later the same pharynx will evacuate its waste.  You can watch it attack a worm in this video although you may want to mute the sound.

The BK produces very little toxin and it is not harmful to humans or their pets.  One source says it is a pest for farmers because it kills worms but it is hard to imagine there are enough of them to be a problem.  I am thinking it might make a nice pet for a Nature Nerd.  Pat, are you game?
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Much more detailed information on Bipalium kewense can be found at  this Wikipedia link and Entnemdept.ufl.edu.

Saturday, October 6, 2018

Monarch Parasitoid Tachinid Flies

Tonya Smith, MN, told me about her recent experiences with monarch motherhood and Tachinid fly parasites and I asked her to share her story and photographs on the blog.


Tachinid Fly Parasites on Monarchs
Tonya Smith
Monarch chrysalis with signs of a parasitoid - Tonya Smith
Success, free at last
One of the many wonders of nature is the metamorphosis of the butterfly. I learned the basics in school, but now I was successfully raising one monarch caterpillar observing the process first hand. I was hooked ... on butterflies! From my training for being a docent at Bill Roston Butterfly House, I learned less than 5% of butterflies reach their adult stage. Of course, the good news is our planet would be defoliated if we didn’t have the checks and balances in nature to control the ravenous caterpillars in the Lepidoptera order which includes moths and butterflies.

Fast forward several weeks from my first experience raising a monarch caterpillar and it’s release. The swamp milkweed in my perennial garden had an abundance of the famous black, yellow and white striped caterpillars.  My morning and evening “cat walks” became a regular occurrence, hoping to observe the ones that were leaving to pupate so I could watch over the chrysalids.  I noticed many small caterpillars leaving the host plant possibly because it was over populated so I took some young instars in to finish raising them.















Cat with a strings attached
Soon the horror show got underway. Caterpillars got into what appeared to be a healthy “J” position, but time would prove their bodies were parasitized. The caterpillars became limp and out came the tachinid fly larvae on gelatinous tendrils that look like white strings. In some cases, the caterpillar successfully formed the beautiful green chrysalis. But excitement turned to disappointment once the chrysalis became discolored and holes appeared for the tachinid fly larvae to exit. The success rate of the ones I was raising was zero percent.This scenario was replayed in my yard as I saw caterpillars and chrysalids hanging from the soffit or brick that had succumbed to the tachinid fly.

Tachinid eggs - Gord Harrison
So here was the living proof of nature’s checks and balances. Tachinid flies belong to the Diptera order and are in the Tachinidae family.  Their larvae are internal parasites of immature beetles, butterflies, moths, sawflies, earwigs, grasshoppers, or true bugs. The adult fly may lay its egg on a host species or penetrate it to place the egg inside.  The fly may even lay her eggs on plants where the maggots can be ingested by the future host after they emerge.
First look outside with more to come
Once inside, the maggots begin to consume the hosts by eating non-essential tissue first which allows the host to continue to grow and feed normally. Only when this material is fully consumed, will the larvae turn to eating vital organs. It’s in the tachinid larvae’s best interest to allow their host to live as long as possible so they can grow fast. The larvae then pupate into adults inside or emerge to pupate outside the prey’s body as seen in my monarch's video. For a real world replay of The Blob, see my video.

Three in a chrysalis
Leaving home












Karen Oberhauser is an Associate Professor in the Dept. of Fisheries, Wildlife and Conservation Biology at the University of Minnesota. She and her student, Michelle Prysby, started the Monarch Larva Monitoring Project in 1996 which studied the reproductive ecology, host-parasite interactions, and factors affecting the distribution and abundance of immature monarch stages. Their research showed that the species Lespesia archippivora is the most important monarch tachinid parasitoid. It is widespread throughout North and Central America, has been found in Brazil, and was purposely introduced into Hawaii for biocontrol in 1898. More details are at Monarchlab.org.

Oberhauser's report titled, Tachinid Flies and Monarch Butterflies: Citizen Scientists Document Parasitism Patterns over Broad Spatial and Temporal Scales (author Karen Oberhauser), cites an approximate 92% mortality during the egg and early larval stages from other natural enemies than the tachinid fly. In a study where volunteers collected and reared monarchs in all immature stages, they found from one to twelve flies emerged from individual monarchs. Later stages tended to produce more flies per monarch when comparing the 1st-3rd to the 4th-5th instars. So monarchs collected during the later stages were more likely to be parasitized and the daily risk of parasitism was higher during the middle three stages. This of course is why it is recommended to raise monarchs from the egg stage. So eventually my “cat” walks turned into a search for those that needed to be euthanized after observing the signs indicating larvae were using our beloved monarchs as their host body.

Larva on the move
"Which way to a pupation station?"
An article in American Butterflies reports on a study of fly parasitism across North America which found up to 30% of monarchs die from parasitoid attack in some regions and years, with up to 10 fly maggots emerging from a single monarch pupa. These high rates of parasitism suggest that tachinid flies could be a major factor regulating wild monarch populations. When Butterflies get Bugs: The ABCs of Lepidopteran Disease.

While many of us curse the tachinid fly, there are those who welcome and attract these parasitic insects and for good reason. On an agriculture level, they help control major crop pests including cabbage worms, Gypsy moth, Colorado potato beetles, corn ear worms, cucumber beetles, cutworms, earwigs, four lined plant bugs, Japanese beetles, Mexican bean beetles, sawfly larvae, squash bugs, and tobacco budworms. In fact, one Organic Farmstand and Education Center in Vermont states, “Never destroy caterpillars with white eggs on their backs as these will develop into more tachinid flies.” So for those of you with vegetable gardens, provide tachinid flies with a diversity of plants with small flowers including flowering herbs, and plants in the Aster family. Cedarcirclefarm.org
 
Tachinid pupa
Tachinid fly emerged











There are several viral and bacterial pathogens that can infect monarchs, including a nuclear polyhedrosis virus and Pseudomonas bacteria (Brewer and Thomas 1966, Urquhart 1987). Protozoan parasites such as Ophryocystis elektroscirrha and a microsporidian Nosema species have also been identified in wild and captive monarchs. Much work and effort is invested in helping the monarchs. Besides the destruction of habitat and climate changes, I realize it is a great tug-of-war between natural predators and human intervention to improve the monarch population. Monarch Parasites and Natural Enemies

You can review all of my tachinid fly photographs in this Flickr album.
Meanwhile, I prefer to end on a positive and happy note with a short video (here on Youtube) of a monarch that beat the odds and hopefully is one of many hibernating in Mexico this winter."

Saturday, September 29, 2018

Mosquito and Other Bites


Did you ever wonder what a mosquito bite looks like close up?  So did I, so here it is.  I felt it land on my arm, probably the movement of the hairs.  I had been photographing other little insects gnawing on me this weekend so it only took about 30 seconds to get my camera out and change the settings.  She wasn't bothered in the least with having a big camera two inches away.

While I was working one handed with the camera, she (only female mosquitoes bite) was searching under my epidermis for a blood vessel.  Once found, she injected saliva with anticoagulant to insure that the blood would keep flowing into her proboscis.  So far, this can be painless but my body's immune system had been alerted and it released histamine at the site.  This caused the sting and the subsequent  swelling.  When you slap, you probably have her saliva on board so just hope she hasn't been promiscuous with a disease carrier!

"I can't believe I drank that much"  (After 2 minutes)
National Geographic has more detailed information on how the proboscis works.  Frequently compared to a hypodermic needle, it is much more complex than that.  For one thing it is very flexible, bending and twisting in the tissue under the epidermis.  Rather than a hollow tube, it is a sheath that introduces 6 mouth parts under the skin.  A pair of mandibles and another pair of maxillae (same name as your jaw) grip the skin so it can push deeper in the search for blood.  Their video even shows the blood vessel compressing as the red cells are drawn in.

Last week we were in Bob Ranney's back yard when I grabbed at a slow flying insect.  We argued about what it was as it was bigger than the mosquitoes we see at Bull Creek, but as usual he was right.  This turned out to be an Asian Tiger Mosquito, Aedes albopictusIt arrived in Texas in 1985 and spread rapidly, now extending from Oklahoma and Missouri to Pennsylvania. (CDC)  They can range from 3-10mm depending on food size, so Bob's was well fed.
"This mosquito has become a significant pest in many communities because it closely associates with humans (rather than living in wetlands), and typically flies and feeds in the daytime in addition to at dusk and dawn. The insect is called a tiger mosquito for its striped appearance, which resembles that of the tiger."  Wikipedia.
Lacewing larva
Most of the species I photograph giving me little bites are never identified.  I am excluding wasps, predaceous diving beetles and hellgrammites. These are bites that require an immediate response, coupled with an announcement such as "*&^%$, you **&#@."  My favorite minor bite was from the lacewing larva on the right which let go just before the picture.  It seemed to have nothing to gain from subduing me and I suspect it was just curious.  Aside from the tick below that was slurping up my juices the others are unidentified.  Any suggestions are welcomed.

Unknown digging in.
Unknown biting hand that fed it

Tick at lunch

Tuesday, September 25, 2018

A WOLF Field Trip

White furcula moth - Furcula borealis
The best way to find small insects is to take WOLF School students on a field trip.  At Bull Creek last week our focus was on plants and leaves but inevitably a sharp eyed student will say "What is this?" and viola! an insect.  They had two great finds, very small caterpillars.

The caterpillar above is Furcula borealis, the white furcula moth.  It has two long tails off the tip of its abdomen (Furcula means forked).  The green and brown camouflage mimics a damaged leaf.  The curved posture is typical, seen in most of its photographs.  They are usually found from April to late August when the second brood cocoons up for the winter.  Our friend put on quite a show of evasion techniques in this video.

Mid August- Lavers




They feed on Prunus species (plums, cherries, peaches, nectarines, apricots, and almonds), cottonwoods, and willows like our specimen was munching.  We tried raising ours on willow but it failed to thrive after a week.   Norman and Cheryl Lavers on the other hand found a F borealis caterpillar in its last stage and document it with this beautiful series of photographs of the rest of its life cycle.
Cocoon 5 days later - Lavers
"We found this caterpillar feeding on black cherry in our garden, and brought it in to raise.  Eventually it was woven so tightly it was opaque, and had taken on the color of the stick it was attached to. Looking like a thickening in the wood, it would spend the winter in plain sight.  On this date the caterpillar attached itself to a narrow stick and wove a thin cage around itself, inside which it could be seen weaving a more solid cocoon.  It somehow pushed a hole in the rather thick cocoon the following April."

The following April - Lavers
Adult moth emerged - Lavers












Buckeye the butterfly - REK



The other lepidoptera find of the day was the colorful caterpillar on the right which we quickly identified on INaturalist as a common buckeye, Junonia coeniaThey are found from the East to the West Coast.  Buckeyes have been among our most commonly seen butterflies the last few weeks.  This is the time of year when the buckeye tree's seeds are dropping to the ground but the timing is coincidental.  Buckeye butterflies are named for the "buck eyes" on their dorsal wings, not their choice of foods.


Side view

The caterpillars of these butterflies prefer plants that produce iridoid glycosides, bitter compounds that release a hormone called gastrin that activates the digestive system and stimulates their appetites, particularly when found in plants like one of our common yard weeds, plantain, Plantago lanceolata or P. major.  They also feed on snapdragon and toadflax.  I suspect I would need an appetite stimulant to eat something called toadflax.
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Just emerged September 28th.
Just emerged


Empty chrysalis