Wasp Watcher: First Real Try

Wanted: emerald ash borer, or any of several invasive oak borers.
Place: West Middle School.  
Date: July 17th   
Time: 2:00-4:30pm   
Number of wasp colonies: 25-31  (Six had no fresh soil around them)
Haul: one (count 'em ONE beetle, netted along with wasp.  (None found on ground.)

Lessons: It doesn't pay to go early--wasps were still digging out when I arrived, since holes would appear where I had already searched.  Also, the half-dozen wasps I netted were all in the final hour, so they weren't flying much earlier.

I learned in training that netting wasps was fun, and added to the total of beetles collected.  (As well as being more certain, since the beetles wasps carried were certain to be the right sort.)  But most of the beetles would be found on the ground.  This was because wasps were sloppy, or dropped those they decided were not good food for their kids.  (One possible explanation: a beetle dies after capture instead of being merely paralyzed.  The babies like their meat still breathing.)  I seem unable to find beetles on the ground.  (Either that, or my wasps are much more efficient than the run-of-the-mill.  Since these are West Middle School Wasps [rah!] that is probably the explanation.)

 My insect net arrived today from Amazon, so I got going.

 One of my employees: the wasp Cerceris fumipennis aka "smoky-winged beetle bandit".

Note the band on the abdomen, and especially the three yellow spots on the face.

The afternoon wasn't a total loss, since a pair of unfamiliar birds

came to sit on a fence, sing and have their portraits taken.
Eastern kingbird, maybe? but this bird has a yellow beak.

 

Last night I found an email from our handler, who casually noted that another worker had closed out his site by collecting eighteen beetles yesterday.  18!!!  I am a real slacker!  (Our total target per site is 50; after we collect that many, we leave the females wasps alone to reproduce in peace.)   To make matters worse, the one beetle I netted may have simply been in the way of my net, since it was quite lively--not paralyzed by the wasp's sting.  Well, there's always tomorrow.

Jeff Michals-Brown: Wasp Watcher

Well-equipped Wasp Watcher on a baseball field:

Bag with water and sunscreen--CHECK

 Vial of alcohol (for preserving beetles, mind you)--CHECK

Indiana Jones hat set at a fashionably rakish angle--CHECK

I am now an officially trained Wasp Watcher.  I will spend a few hours each day or so from now to early August monitoring colonies of Cerceris fumipennis wasps in their preferred habitat: nearly bare, hard-packed sandy soil like that around a slightly down-at-the-heels baseball diamond. 

Why, you ask, would I want to stand in the hot sun for hours at a time watching wasps?  It's part of a nifty trick called biosurveillance.  The wasps are, in fact, working for us; and I am watching to see what beetles they bring home.

 Cerceris burrows look like ant hills with over-sized openings.

Soil is piled up evenly all around, and the hole is big enough to put a pencil in.

 

"Smoky-winged beetle bandit," wasp is the common name tentatively given to Cerceris fumipennis.  The yellowish band around the base of the abdomen is easy to spot, but not diagnostic: Cerceris fumipennis has look-alike relatives.  The real McCoy also has three yellow spots on its face.

 

You can be sure you have the right wasp when you see it enter or leave its burrow!

NOTE: the wasps are on the small side, and don't seem able to sting humans.

 

The "wrong" wasp, digging the "wrong" hole: 

notice the soil is almost all to one side.

It started for me a year ago when the majestic white ash in my back yard took sick.  Leaves yellowed and fell all summer and fall until it was bald before its time.  So I did what anyone frantic with worry would do: I turned to Google.  I quickly turned up the Mother of all ash killers: the Emerald Ash Borer.  The EAB is an invasive alien beetle from Asia which probably came into this country accidentally--like so many alien invasives before it.  It was discovered in Michigan and nearby Canada in 2002, after being imported in packing materials, probably years before.  The beetle has spread rapidly, reaching a point north of Boston just last year.  The ash trees that evolved with the EAB in Asia can usually survive an infestation, but all ash trees on this continent die.  The adult beetle eats ash leaves, causing little damage, but the beetle larva bores under the bark; the damage to the bark usually girdles the tree and kills it in a matter of months   I watched my tree anxiously for signs of beetle infestation.  The good news: my tree didn't have them; it was sick with something less serious.  The bad news: the Emerald Ash Borer was spreading unchecked, and was expected to eventually eliminate ash trees wherever in North America they were.  The EAB was recently ranked the most destructive insect in the country.  My tree, currently in the bloom of health, is doomed--so is yours.

Sadly, we have aided the Emerald Ash Borer in its spread.  On their own they might migrate a few miles in the space of a year; at that rate, we should have had many years to deal with the problem.  However, if the larvae happen to burrow into a trunk that later becomes firewood, and someone transports that firewood to another place, the beetle spreads astronomically faster.

What does the wasp, Cerceris fumipennis, have to do with this?  The wasp is a good card-carrying native, and harmless to humans.  But it is a fierce predator to certain types of beetles: those wood-borers of the family Buprestidae, called Jewel Beetles.  It stings the beetles, and carries the paralyzed insects back to its burrow to lay its eggs on.  The wasp is good at catching beetles, and Wasp Watchers are good at catching wasps.  In effect, the wasps are sampling the local beetle population, and doing it far more effectively than we can.  We need only confiscate some of the beetles to find out who's out there.  The collected beetles go on to experts who will identify them. In short, we are putting wasps to work finding us invasive wood-boring beetles.

Although the EAB isn't hard to identify, collecting all those beetles may give us an early heads-up on the next invasive--maybe early enough to eliminate or control it.  North America has already lost its chestnuts to chestnut blight, most of its large elms to Dutch elm disease, and it's rapidly losing ashes --some of the most majestic forest trees remaining.

I don't want to lose any more.

I hope to God not to find a half-inch long, narrowly oval, metallic emerald green beetle among the wasps' prey.  But if I don't find any this year, I'm sure I will next.

https://en.wikipedia.org/wiki/Emerald_ash_borer

https://en.wikipedia.org/wiki/Cerceris_fumipennis

http://www.emeraldashborer.info/index.cfm

http://cerceris.info/index.html

Eastern Hemlocks and the Threat of Woolly Adelgid

Full-grown.

Undersides of flat needles are striped.

Spring growth.

Young cones.

Mature cones.

From the spindly trees folks grow around here, and the way they crowd them and torture them into HEDGES, for all love, you'd never know that the eastern hemlock(Tsuga canadensis) is a majestic member of late-stage successional forest here in New England. 

I have been collecting locations of eastern hemlocks (Tsuga canadensis) on my neighborhood perambulations over the last month or so, and have a nice list of trees I look at regularly.  I was moved to do this less because of its iconic status--the third most prevalent tree in Vermont--than because of the danger eastern hemlock faces.  This tree is endangered by yet another of our many alien invasives: the woolly adelgid.  

Our local trees range from sad and tortured to moderately majestic.

 

 

Woolly adelgid (Adelges tsugae) was imported accidentally from Japan, and was first noticed in the US near Richmond, VA in the 1920s.  It is now affecting eastern hemlocks as far north as Massachusetts.  Woolly adelgid is an aphid-like "true bug" (insect order Hemiptera) that sucks the sap and starch from hemlock twigs, reducing their food stores.  This weakens the tree, allowing other insect, disease and drought stresses to overwhelm it.   

Wooly adelgid spreads short distances mainly by wind, and by birds and other animals the sticky egg sacks cling to.  Transport of infected nursery trees can spread the insects more widely.  

 

Each cottony mass tyically hides an individual and its several hundred eggs.

You will know you have this on your hemlock tree if you see the cottony egg masses on the undersides of twigs.  Affected trees will gradually lose needles, becoming more "transparent" and turning grayish.  Trees here in the north typically die four to ten years after infestation.  If allowed to expand unchecked, the woolly adelgid could doom so many of these beautiful trees that whole forest ecosystems could be irrevocably altered. 

Property owners can spray their smaller infested trees yearly with a non-toxic insecticidal soap or horticultural oil; these smother the insects.  Tree foliage insecticides will keep on killing for several years, but are more toxic.  Trees too large to spray can be treated with soil drenches or other chemicals that are absorbed and transported throughout the tree, but are not safe applied near bodies of water.  For whole forests, several insect species that feed exclusively on wooly adelgid were deployed beginning in 2002 in hopes of bringing the pest population down to manageable levels over the long term.  

A nice video pulls all this (and more) together here.

  

 

My own little darling at about ten years old is almost chest-high, and free of adelgid.

There are a dozen or so stands of eastern hemlock around my neighborhood, many consisting of several trees.  (Probably thirty or more trees of all sizes could be counted if including individuals in hedges.)  Of these, three stands have obvious signs of woolly adelgid.  There may well be more--I cannot closely examine trees in other people's yards.  My own was a tiny individual transplanted to the woods behind our house; ten or so years later it is only waist-high, but free of insects.  If landowners keep an eye on their own trees and treat them if needed, I have hopes that the spread of the insect can be slowed--at least locally. 

What can you do?  If you have any hemlocks, watch them.  If you find woolly adelgid, consult with state agencies on what treatment would be best.  If you see the insect on your neighbor's tree, let them know.  Don't move an infected tree to a new location.