Thursday, October 29, 2020

Acorn Weevil


This August I found this long-nosed beetle in a patch of oak trees.  Although it looks dangerous with a snout almost as long as its body, you should "fear no weevil," for it attacks only plants.  With its long slender beak and its sharply elbowed antennae, it is identified as a nut and acorn weevil, a member of the genus Curculio with over 30 species on our continent.  Many of these make their living on oaks.

Curilio female weevil.  Females have the longer beak
A few years back we traveled to Taneyville to make nature mobiles with a  5th grade class.  The students had collected a variety of nature finds for elements on the mobiles including bags of acorns.  At the end of the session, a student came up to me and generously offered me part of his collection of acorns to use for another class.  I sealed them in a ziplock bag and 24 hours later I found a Curculio larva in the bottom of the bag adjacent to a newly drilled acorn.

Once out of the bag, it laid still for a minute and then started to make its getaway, looking for some nice soil to pupate in for a couple of years.  It was slow moving so I had lots of time to set up for this macro movie to document its progress.

Inserting the egg -click to enlarge- USFS


Life begins for a weevil when a female bores into a green developing acorn and deposits a single egg.  She seals up the tiny hole with her fecal material and the larva will emerge from the egg to find shelter and sustenance.  After consuming most of the nut's contents, it carves out a round hole and struggles out of the acorn.  The larva will then crawl off into the soil to pupate.

 

Larva emerging an acorn - Jay Barber
The pupa may not emerge for over a year, coming out as an adult in the summer, hopefully at the time the acorns are greening up.  After mating, the female begins a long climb up a mature oak to start the cycle again.

Larva in acorn - USFS

The whole process is shown in this short National Geographic video.

A fun fall activity is to collect acorns and crack them open to find weevil larva.  Put them in a pan of water and save the ones that float to crack open for the larva.  The space that the larva has chewed out makes them buoyant.  On the other hand, if the sink "you will see no weevil".  Sorry......no, not really






Monday, October 26, 2020

Aphids Make Wax


Ben Caruthers sent me some photographs of aphids on his milkweed.  The picture above was particularly interesting as it showed the aphid extruding wax from its cornicle (corn-ick-L).  Another name for the organ is siphunculi, and yes, Googling can tell you how to pronounce itNote to self- must get out of the house more often.

Aphid with cornicle wax - REK
Cornicles are the little tail pipes on the rear of aphids.  Initially thought to secrete the sweet sticky honeydew so beloved by ants, we now know that they put out a substance called "cornicle wax."  These droplets are a quick-hardening defensive fluid containing triacylglycerols.  Muscles at the base squeeze the fluid out like an eyedropper, as seen in this Youtube clip.

 

 

 

"A.F.G. Dixon was one of the first to propose a defensive function in 1958. A 1967 paper published in the journal Nature, “Defense by Smear” by John S Edwards more fully described the defensive function of cornice secretions. Edwards had collected aphids from the field with parasitoids stuck to the cornices. In laboratory observations, he noted that poking an aphid would induce it to release a droplet from the cornicle on the side that the poke was received. He found that droplets collected from aphids quickly crystallized. The droplets were capable of immobilizing predators." Living with cornicles

Ben Caruther's aphids and an immobilized unknown bug

As you might expect the types of lipids that are excreted differ among aphid species.  Some have proven to be alarm pheromones that send a signal to other aphids, causing them to drop from the plant to safety.  We discussed the pheromones at length in this past blog  Since then a lot more information has become available, some of which is in this blog. 

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Everything else you might want to know about aphids is compiled in this link.

Saturday, October 24, 2020

The Case of the Yellow Feathers

Female Flicker - Wikipedia

I found these feathers in a recently burned grass field, scattered with a lot of downy feathers.  They were 5-6" long, too big for a goldfinch.  I sent the question to my bird detective, Dr. Jay McEntee at MSU.

"Those are Northern (yellow-shafted) Flicker flight feathers! I believe flickers are the only birds in North America that deposits carotenoid-based colors in the feather rachises (the shafts). Carotenoids are used to make bright red, oranges, and yellows. So carotenoid pigments are what makes the red in a cardinal's feathers."

 

All the feather and down was within a three foot circumference in the middle of the blackened grass stubble, which looked like the kill site.  There wasn't any disturbance in the periphery and the flicker should have seen any attacker coming unless it was from above.  My guess was a Cooper's Hawk and I was back to Jay,

"I've seen Cooper's Hawks take woodpeckers before - they are a very likely culprit as you suggest. A flicker is a really substantial meal. They're surprisingly big "in the hand." Also, flickers like to eat ants, and the fire might have created some disturbance for underground ant nests that brought more to the surface. So as a natural history story, that all hangs together very well, in my opinion."

Lunch in the soil - Lindsay Firth
I had seen ants and a few small beetles in the blackened stubble which probably caught the eye of the victim.  Our Northern Flicker is a woodpecker that isn't afraid of getting its beak dirty.  

"They eat mainly insects, especially ants and beetles that they gather from the ground.  Flickers often go after ants underground (where the nutritious larvae live), hammering at the soil the way other woodpeckers drill into wood.  Their tongues can dart out 2 inches beyond the end of the bill to snare prey." Cornell Lab


All About Birds says this about Cooper's Hawk.  "Cooper’s Hawks mainly eat birds. Small birds are safer around Cooper’s Hawks than medium-sized birds," and goes on to list the Northern Flicker as a common victim.  Feeding in an open blackened field was risky behavior.  I can't prove that a Cooper's was the perpetrator but I would consider it justifiable avicide, just what it does for a living, filling its role in the food web.

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Breaking news:

Becky Swearengin shared this flicker feather from Estes Park in September.  The red shaft is a sign of the Western subspecies.  "The western red-shafted flicker (C. a. cafer) resides in western North America. It is red under the tail and underwings and have red shafts on their primaries"  Wikipedia 

Wednesday, October 21, 2020

Shiny Wolf Spider

Mark Bower sent me this photograph of a spider carrying babies on her dorsal abdomen. The only spiders that do that to my knowledge were wolf spiders and I couldn't find a black shiny wolf spider in any of our books. I sent the photo off to experts and got this response from David Bruns from MDC at Powder Valley Conservation Nature Center.

"Female wolf spiders are the only spiders I know of that carry their young on their abdomen.  More than 40 species of wolf spider have been documented in Missouri. They are an incredibly important group of spiders because of their abundance, particularly in forests, where they eat countless insects that can damage trees and plants.  They are considered harmless, meaning that they do not have venom that is medically significant to humans."

The photo is of a female Allocosa sublata. This species is recognized by its medium size, (as spiders go), the shiny black carapace, and dark rings that can be discerned on the tibias of the legs. This is an uncommon species in Missouri and the photo is extraordinary since it captured one with spiderlings which remain with the mother for only a few days. The mother does not provide direct care to the young, but provides protection from predators (particularly other wolf spiders) and serves as a mechanism to disperse the young. These will overwinter in the leaf litter as young spiders.

Allocosa sublata - David Bruns

You can compare David Bruns' photograph above with this full description in  Bugguide.

""Carapace dark red brown to black, sometimes iridescent, darker at margins, with few setae. Sternum orange brown. Chelicerae dark red or red brown. Legs dark orange or red brown, sparsely covered with setae; femora and tibiae each with 2 indistinct, dark rings. Abdominal dorsum dull red, densely reticulated with black."

 






Thursday, October 15, 2020

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.

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"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."

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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.

Tuesday, October 13, 2020

Bee Bully

 

Chris Barnhart sent me photos of another invasive species he filmed at the Botanical Center. It’s the European wool carder bee Anthidium manicatum. A native of Asia, Europe and northern Africa, it was accidentally introduced into North America in the 20th century and has become a pest in some regions. It has been labeled "the most widely distributed unmanaged bee in the world."

Click to enlarge

The males are very territorial, and attack other bees foraging in what they consider their territory. They have five sharp spines on the last segments of their abdomen which are used while defending their territory from other bees. (see photo above) There is concern that they might damage bumblebees and other native pollinators. Chris got this cool video of the carder male attacking which is at this Youtube link.



These are solitary, cavity-nesting bee species in the family Megachilidae, a family whose members include the mason and leaf cutter bees.  The name "carder" comes from their behavior of scraping hair from leaves such as lamb's ears.  Females have large mandibles with sharp teeth used for collecting and manipulating plant trichomes (hairs) for their brood nests. They also have short, dense, compact setae on their lower legs (the basitarsi) which help to organize the collected plant fibers into a ball. They then carry this bundle beneath their bodies to be used as a nest lining. (Wikipedia)  

There are more anatomical details at Featured Creatures including what impact they may have on our natives species.  Carder bees tend to be more common in urban settings which tend to have more non-native flower species that they may be more adapted to.  The amount of damage they cause from injuring bees, pollinating and spreading non-native plants and reducing bumblebee populations by aggressive competition is an ongoing question.

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All photos and video by Chris Barnhart.

Sunday, October 4, 2020

Horntail Wood Wasp

I found this dangerous looking critter in 2017 and sent it to Bugguide, tentatively identified it as a horntail wasp in the family Siricidae.  Now three years later I got a response that it is Sirex sp.  Close enough for me.

Horntails are in the order hymenoptera like bees, wasps ants and the sawflies we recently discussed.  They are xylophageous, meaning that they are herbivores that eat wood.  That spike at the rear end is the ovipositor, an impressive drill that bores into the tree and deposits an egg and a fungus.  Wikipedia describes it for Sirex noctilio like this:

"...as stiff and straight as a needle, polished black, with slight notches in the pointed half. It is hinged, to permit of its being turned at right angles to the body. . . the female selects a tree that is not too healthy, and settles on the bole; then, turning down her boring instrument on its hinge, she drives it through the thick bark to the solid wood."

Dorsal view - note ovipositor

When the egg is inserted into the wood it is accompanied by a fungus that will digest the wood.  Like many xylophageous beetles like the ambrosia beetle, the horntail has mycangia, pits that nourish and carry the fungus to where it lays the egg. insuring a food supply for its young.

The larvae hatch and begin tunneling through the wood for up to two years.  Toward the end of their larval phase they dig their way up close to the bark before pupating.  Once they emerge they only have to dig their way to the surface to fly away and mate.

I don't have a species identification of our Sirex but it isn't Sirex noctilio.  This is the European wood wasp, a serious invasive species which causes the death of many pines in the Northeastern US.  It hadn't  reached Missouri in 2013 when MDC Discover Nature warned about its possible approach.