Differentiating Grasshoppers

Even in the cool drizzle on a tiny patch of reconstructed prairie, our MN field trippers found several grasshoppers clinging to the stalks.  We tend to take them for granted, but grasshoppers have their own distinctive life habits.

Differential Grasshopper- Melanoplus differentialis

The differential grasshopper is easily identified by the chevrons stacked on its femur, the "Vs" pointing to its hip.  The early instars are brighter shades of yellow-green to brown, darkening with age.  They are found in much of the US, generally in grasslands and weedy areas.  They have one hatch a year, occuring in mid summer.

They eat a wide variety of plants, preferring ragweed and sunflowers, and grow faster when eating forbs (herbacaeous flowering plants) instead of grasses.  Unfortunately, it tends to be gregarious and has a taste for eating out in agricultural crop fields with friends, lots of friends.

"The young will feed upon various grains, alfalfa and hay crops while the adults will attack the corn, cotton and deciduous fruit crops. A single swarm can often deplete a younger crop to nothing in a matter of a few days. Because this species has a tendency to stay in large swarms while eating, it is a serious issue for farmers in most of its range."  Wikipedia

Admirable Grasshopper- male

At first glance, the other specimen pictured above is less distinguished, just another brown grasshopper.  Most notable is the angular pointed head with two short antennae.  Their legs are relatively longer than many other grasshopper species.  Looking closely it has black lines demarcating square blocks along the side of its abdomen. 

It is a male admirable grasshopper,  Syrbula admirabilis.  The females are bright green with brown legs and abdomen, quite different from the male.

Male Admirable- Shelly Cox, MDC

Female Admirable - Jon Rapp

So what is so admirable about them?  For one thing, their civilized behavior.  They tend to congregate in weedy areas and thus don't compete with us for commercial food resources, staying politely in their own niche.  They also are an important member of the food web, feeding a wide variety of insect predators.

Eats weeds and feeds wildlife - how much more admirable can a grasshopper get?



 

Bean Weevil Dance

Honey locust bean weevil - Amblycerus robiniae

In January of this year, Bob Korpella sent me a picture of a pile of seeds with a weevil crawling out of them.  They had come from the Nixa Early Learning Center.  We identified them as honey locust bean weevils (Amblycerus robiniae) and we described them in this blog.  I made a note to myself to check out some beans this fall.

I expected at best to find one with a larva, but was surprised to find larva in every bean in the first pod I checked out.  They were little bright yellow critters, knobby on the surface and full of life, apparently annoyed by the premature un-roofing of their hard shelled bean home.

This is the time of year that the ground under a honey locust tree will be littered with their ten inch long flat bean pods.  They appear brittle but actually are quite tough like the thorns that protect the mother tree.  Looking at them you would never guess that there was animal life inside, let alone the squirming larva you can watch in this Youtube video I posted last week.

Obviously an infested bean isn't going to be fertile but that doesn't seem to affect the honey locust population.  These trees are early colonizers of neglected fields, filling the open grass land at Jones Farm upstream from our place.  Any tree that survived the munching of giant tree sloths and mastodons had to be one tough dude/dudess.

Spiders of the Forest Floor

Our P. whitmani- 10 mm (2/5 inch)

This bright little spider, discovered on a training field trip, is a member of the jumping spider family Salticidae, probably Phidippus whitmani.  It is a male, identified by the bright red-orange dorsal surface and white setae (hairs) on the forelegs.  They are found in habitat frequented by velvet ants, (which are actually mutillid wasps) and have a similar coloration and texture.  This provides P. whitmani with Batesian mimicry, helping to protect them from predators that are familiar with the painful velvet ant sting.

These jumping spiders live in the leaf litter and low lying plants in wooded areas like we were exploring.  They hunt by sight, their family having the best vision of all invertebrates.  Moving cautiously while hunting and stalking prey, they make quick jumps several times their body length.  Jumping spiders can be identified by their prominent head and two large eyes forward and their other six small eyes above.

"My what big (central) eyes you have" P.  johnsoni by  Kyron Basu

Jumping spiders are distinguished most easily in the field by....jumping!  Their short hops are a somewhat distinctive first clue.  Their cephalothorax (head+chest, the front section where the legs attach) tends to be large in comparison to the abdomen.  As seen above, the front of the cephalothorax is squared off rather than rounded as many other spiders.  Wikipedia describes some of their other characteristics.

Note large head- P. whitmani-   Stephen Schueman

They do not build webs but use their silk to build shelters for protection against inclement weather.  They also use them during their vulnerable molting period, for storage of egg cases and overwintering housing.  Their silk also serves as a safety line, a good strategy when jumping off into the unknown.

These four minute movie outtakes depict general behavior of our Phidippus whitmani, extracted from a hour long video posted by Community Video.  You can see facing turns, grooming, and feeding on a mosquito, then a fly, followed by an immature Pisaurina mira spider (Araneae: Pisauridae).

This is one of a series on finds on the Master Naturalist training field trip.  More pictures from the  field trip are at Finds from the Field. 

Sumac Flea Beetle

This colorful beetle was found on the Henning CA field trip, crawling on a forest plant.  It looks like it had a bad paint job on its elytra (wing cases) which has been chipping off.  This is a sumac flea beetle (Blepharida rhois) and it is supposed to look like that.  Actually in one life stage it  makes a stink when it covers itself with makeup, but we will get to that later.

Sumac Flea Beetle (Blepharida rhois) -wiki.bugwood.org

These little beetles measure a quarter of an inch in length.  They have enlarged hind femora (think thighs) with internal spring mechanisms that allows the insect to jump, the source of the "flea" in their name.

Sumac Flea Beetle Larvae- wiki.bugwood.org

The larvae are dull greenish-yellow and about ½″ long. Their obligate host plant is one of the many species of sumac which vary depending on the location and climate.  They feed on the sumac leaves leaving a scattered hole pattern that looks like it had been hit by a load of fine birdshot from a shotgun.  After feeding into the early summer, they crawl into the soil to pupate, emerging as adults mid summer.  The adults continue to consume sumac leaves until they seek their winter shelter.

Now about that smelly makeup.  Like other beetles in the Blepharida flea beetle genus, the larvae of B. rhois retain their feces on their back rather than discarding it, a practice referred to as a "shield defense."  A study by Venci and Morton in Chemoecology showed that predatory ants attacked all the uncoated larvae and none of those bearing this shield.

Another species example of fecal shield defense  Zookeys

So was it the shield or the smell?  They next fed some larvae only lettuce which they again employed as a shield and the ants attacked them as though there was no shield.  It was obviously not the physical barrier or aesthetic concerns that put off the ants.  Further studies showed it was the chemicals they derived from their sumac host plant.

"The shield defense was a mixture of three fatty acids, a suite of tannins, their metabolites and phytol. All shield compounds or their precursors were obtained entirely from the host plant. Pure standards of shield compounds were found to be deterrent when assayed. This is one of the first instances of an insect using a mixture of primary and secondary substances for defense against predators."  Shield defense paper

Everything in nature is eventually recycled.  In this case the sumac flea beetle has gone beyond the recycling trend, practicing what is called in current terminology "repurposing." 

*  More information is at Bugwood.org.
This is one of a series on finds on the Master Naturalist training field trip.  More pictures from the  field trip are at Finds from the Field.  

Velvet Ant - Not

Someone found this on our recent field trip to Henning Conservation Area.  It was a good catch and a brave one considering its fierce appearance.  On first glance it looks a little like a male velvet ant (the females are wingless).  I posted it on Bugguide.net and within minutes I had a tentative ID, a Spider wasp - Psorthaspis sanguinea.  We are now awaiting confirmation by a specialist.

There is essentially nothing on P. sanguinea on the web.  It is a member of the  Pompilidae family, a group characterized by their powerful sting which paralyzes a spider which is then dragged off to a nest.  A single egg will be laid on the spider, which will remain alive while the wasp larva slowly consumes it until it pupates.

Not only is its appearance enough to intimidate a bug collector, but its nickname "horse killer" should be a clue.  We described the powerful sting of this family, which is ranked at the peak of the Schmidt pain scale, in a previous Tarantula Killer blog,   Fortunately no Master Naturalists were hurt in filming this wasp.

This is one of a series on finds on the Master Naturalist training field trip.  More pictures from the  field trip are at Finds from the Field. 

Fruit of the Oak?

Fruit or gall?

On Saturday's Master Naturalist training field trip, one of the finds was this chewed specimen.  It was firm and had a spot that looked like the insertion of a stem.  There were some wild plums scattered about in the oak and hickory forest but no one obvious source.

Cutting it in half exposed either the single seed of a fruit (drupe) or a larva in a gall.  The color was distinctive, but of what?  Sad to say, Jay Barber called it a gall and nailed me with it.  My only defense is that I was half right - it is an acorn plum gall from an oak tree.  OK, he didn't buy "half right" either.

Gall- NCSU.edu

You can see how it gets its acorn name, as it arises directly from the cap of the acorn.  This is somewhat unique as other oak galls are twig galls such as oak apple and wooly sawyer galls, or leaf galls.  You can see pictures of these here.

Intact larva- MJ Hatfield

Galls in general are the products of eggs from gall wasps, gall midges, and gall mites, while a few others are produced by aphid and fly species.  The egg laid on the parent material alters the plant's metabolism to do its bidding, producing both food and shelter as the larva grows.  Eventually the gall insect emerges, breeds, and lays its eggs in or on a similar species to repeat the cycle.  In our example above the cut went through the larva.  The example to the left shows the larva intact.

The acorn plum gall is formed by a Cynipid wasp, Amphibolips quercusjuglans.  As galls seldom do any significant damage to the parent tree, there is little research on many species.  To quote backyardnature.net:

Gall wasp- MJ Hatfield

"We have over 750 species in 49 genera in the Gall Wasp Family. Furthermore, "Each species makes a characteristic gall on a specific part of the plant. Many make galls on oaks. Most have a complex life cycle with a parthenogenetic generation and a sexual one. Each generation makes galls of a different appearance and on different parts of the plant."

After Bugguide.net links, the trail grows cold.  I hoped to find the derivation of the species name quercusjuglans, a strange mixture of quercus - Latin for oak, and juglans - genus name of walnuts.  This is probably more than most people would care to know about the naming and sex life of this tiny wasp with the big nursery.

Phenology - October

As October begins, start listening as the trill of field crickets replaces the nighttime chorus of frogs.

Goldenrod

Aster

Golden rod and asters are blooming.  Goldenrod pollen is nothing to sneeze at - it gets all the blame for ragweed pollen.  Asters provide much needed late season nectar.

Pigmy rattlesnake

Junco

Snakes den up and find sites to overwinter.

We think about birds that migrate away to the south from the Ozarks, but juncos migrate down from Canada to the Ozarks for the winter.  

Trills of field crickets will be replacing the frog chorus in the fading light.  Jay Barber tells us that the jumping bush cricket is the last one to sing before winter hits.  Tune in to learn its song here.

With the first cold snap, lady beetles begin to congregate in houses and outbuildings, covering a small space as though to share each others' warmth.  Turn on the furnace and they will be flying around in the house, leaving a little stink if they are squished.

October 29 is average first day of frost in the Ozarks.  When the first hard freeze is predicted, get out early in the morning to look for frost flowers.  They are extruded from the base of frost weed (Verbesina virginica) and other plants.  You may be able to report a new parent species!

Blue jay with acorn

Not only do squirrels and chipmunks gather acorns for their winter feed but the blue jay does too! Blue jays carry food in their throat and upper esophagus—an area often called a “gular pouch.” They may store 2-3 acorns in the pouch, another one in their mouth, and one more in the tip of the bill. In this way they can carry off 5 acorns at a time to store for later feeding. Six birds with radio transmitters each cached 3,000-5,000 acorns one autumn. 

Their fondness for acorns and their accuracy in selecting and burying acorns that have not been infested with weevils are credited with spreading oak trees after the last glacial period.  Cornell Lab of Ornithology

Peak fall colors are coming.  These are just a few of the types of oak leaves you will see.