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Extension Entomology

Category: Lawn and Garden

A Word Regarding Japanese Beetle (JB)

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

Japanese beetles have become a firmly established pest species in portions of Kansas.  Potential damage is twofold.  Most commonly, Japanese beetles indiscriminately feed on nearly 300 plant species including fruits, vegetables, agronomic and forage crops, ornamentals, trees and shrubs. Often times, host plants are literally covered with the gregarious beetles which rapidly consume any and all foliage and floral plant tissue. A second type of damage is associated with the “white grub” larval stage as a potential turf pest.

While some individuals prefer to calculate/record accumulated Growing Day Degrees50 as a method to predict the initial yearly appearance of Japanese beetles, one can more easily set out traps baited with the JB pheromone and floral lure.  The bonus is that this also tells an individual that JB actually are “in-the-neighborhood” as evidenced by their being captured.

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First 2015 reports of JB captures:  Desoto June 9; Manhattan June 15; Topeka June 16.   Look for their numbers to rapidly increase.  People concerned with JB feeding on landscape plants need to be vigilant in inspecting plants for the presence of JB.  If present and if in damaging numbers, corrective actions should be undertaken.  Refer to K-State Research and Extension Publication MF3151 – Japanese Beetle, which is available and downloadable on-line.

The Deafening Sound of Silence – Where are the Periodical Cicadas?

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

It is a few days past a month since my first encounter with the Brood IV periodical cicadas.  What an enjoyable treat it was living with the “little beauties”.  It was impossible to escape the cacophony of millions/billions(?) of male periodicals “singing-their-songs” in tree tops.

The response to the oft asked question, “How long will they be making a ruckus?”, was that by the end of June, they will have run their course.

 

And so it has come to pass.  Off my back deck, the nearby cassini ceased their calling on June 18 (this cluster was restricted to just several trees in the ravine area immediately behind my house).  On Father’s Day, I called my visiting daughter out —- to hear one (maybe two) septendecim(s) calling further down the way.  Nothing since.    

 

I have purposely driven several routes where the blare of periodicals was inescapable from both sides of the road.  Over the past week, the calling diminished to just sounds from occasional groves.  And the last 3 days, all has been quiet.  While there may be some occasional reports of still active pocket populations of periodicals, those too will soon cease.  Essentially, the 2015 emergence has come-and-gone.

 

What has been left behind are the eggs that were inserted into tips of branches.  This will become evident with the eventual appearance of dead brown terminal portions of branches.  People should not be concerned about the health and vigor of their trees.  Just consider this to be a minor “natural pruning”.  The tiny nymphs that hatch and drop to the ground will burrow into the soil and begin their 16-year developmental cycle which will culminate with their emergence in 2032, and the next Brood IV of 17-year periodical cicadas.

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Millipedes On-The-March?

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

While I am not saying that this will happen, the excessive spring rains might be conducive to promoting movements of massive populations of millipedes.  Millipedes in of themselves are harmless (do not bite, sting transmit diseases), and in fact are beneficial in their natural role as decomposers (feeding on dead organic matter).  It is the sudden presence of large populations moving in and about residential properties that can be disconcerting.

Millipedes are elongated wormlike arthropods.  They can be differentiated from centipedes by virtue of the number of legs per body segment.  Whereas centipedes have a single pair of body legs per segment, millipedes appear to have 2 pairs per body segment.  I use “appear” because what appears to be a single body segment actually is comprised of two fused segments, each with a pair of legs.

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The two most common body forms for millipedes common are cylindrical and plated (flat-backed).  Cylindrical millipedes are sometimes referred to as “wireworms” (not to be confused with “true wireworms” – the larvae of click beetles), and when viewed from above, their legs are somewhat hidden due to their ventral position.  The legs of flat-backed millipedes are more highly visible as they project outward from beneath the extended plate.

The life cycle of millipedes extends over a period of years.  Depending of conditions, development from egg to adult may require 2 – 4 years, with adults living additional years.  Thus over time, millipede populations build up (especially) in heavily wooded areas which satisfy their preference for shaded and moist environments where they primarily feed on decaying organic matter, notably leaf litter.

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For reasons unknown, countless numbers of millipedes move/march in droves.  They make their presence known when they invade yards and homes.  This accounts for reports the reports of “worm invasions”. And although millipedes are harmless to people and pets, they may enter garden areas and sometimes feed on tender plants.

The most common complaint, however, is their disconcerting presence. They are mostly observed around daybreak when massing on sides of buildings, patios/decks, driveways and sidewalks and decorative rocks.  Especially on hot sunny days, they rapidly disappear as they seek protective shelter/cover, only to re-emerge during the ensuing evening.

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Frustrations arise when attempting to control millipedes.  Again, millipedes seek “hiding places” —- any available crack or crevice in the soil, under bark mulch, under landscape stonework, gravel, plastic ground cover, leaf litter in and around homes.  Elimination of these protected sites is impractical-to-impossible.  Insecticides registered for use as perimeter treatments will eliminate those millipedes in the target area.  However repeated applications will be required for the duration of millipede invasions.  Another nuisance factor:  the dead millipedes will have to be swept up and disposed of.  The best news is that millipede activities stop as suddenly as they began!

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Nuisance Moths = “Miller Moths” = Army cutworm Moths

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

Recent questions have been received inquiring about the annoying “miller moths”.  Also, numbers of moth captures in my (at home) blacklight trap have picked up

What are they?  Why so many?  What can I do about them?

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“Miller moth” is an all-inclusive umbrella term used to describe any plain brown drab moth.  Because virtually all moth species have wings covered with scales, those scales are fluffed off like dust-in-the-air (as dust associated with flour milling plants).  At this time of year, the “miller moths” of note are army cutworm moths, Euxoa auxillaris.

Upon close examination, army cutworm moths definitely are not plain, brown or drab.  There are 5 morphological forms (called varieties) of army cutworm moths.  Each possesses its own intricate and distinctive wing pattern.  Adding more to the visual array, brown forms of each variety are males, whereas grayish individuals are females.

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The seasonal life history begins in the fall of the year when moths deposit eggs in the soil in fields of fall-seeded wheat, alfalfa stands and weedy fields/patches.  Eggs may hatch within several days of being deposited, but may be delayed under unfavorable/dry conditions.  Larvae preferably feed during the dark of night, and seek shelter in the soil during daytime hours.  Army cutworms overwinter as partially grown larvae (red rectangle).

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Each year in the central plains states, overwintered army cutworm larvae resume their feeding as temperatures moderate/become warmer.  They complete their development towards the beginning of May, after which they burrow into the ground where they create protective earthen cocoons inside of which they pupate.

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Moth emergence usually begins by late May.  Although moths are the mature form of the army cutworm, at this point in time, they are not sexually mature.  For a period of time, moths remain near areas where they emerged.  Then an undefined stimulus (likely photoperiod driven) signals moths across the central plains states to migrate westward to the higher elevations in the Rockies. There in the cool-of-summer, they feed, accumulate body fat and attain sexual maturity.  In mid- to late September, they migrate back to the central plains where they deposit eggs (as previously described) to initiate the next generation of army cutworms.

The current complaints revolve around the moths.  Again, because moths are active during evening hours, they shun daylight.  That is, with the approach of daylight, army cutworm moths seek shelter/cover in any conceivable space.  Excluding moths is difficult because they will exploit very small openings.  Because garage doors seldom are tight fitting, when one opens the garage door, a flurry of moths may rush out.   A car window left open overnight provides an attractive entry point – and when one gets ready to drive to work, he/she will be greeted by a flurry of excited moths.  Open a polycart to deposit a trash bag and you may be greeted by a rush of moths.  Take an early morning walk and as you pass a line of shrubs, you may be startled by hundreds of excited moths darting out.  And so on.  In homes, catch or swat a moth on your wall or curtains/sheers and you will find a coating of “dust” (wing scales) left behind.

An example of the “dust” produced by army cutworm moths can be seen where moths gathered from a single blacklight trap are dumped out of a garbage can.  Talk about being up-to-your-neck in army cutworm moths!

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Another interesting tidbit about army cutworm moths:  food for grizzly bears. During summer months, bears move to the higher elevations to feast on army cutworm moths.  It was determined that single moth possesses ½ calorie of fat content.  It was further estimated that a bear obtains 20,000 calories of fat on a daily basis by consuming 40,000 moths per day.

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When the Dam Breaks, All Heck Breaks Loose – Periodical Cicadas

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

Probably the most famous flood resulting from a broken dam is the Johnstown Flood.  Doubtful that such could ever happen again given that “oldtime” dams were not constructed like modern day dams, and communities would not be put in potential paths-of-danger.  I don’t know all of the details, but extensive rains added to the waters behind the dam building to the point that the dam could no longer hold back the waters.  The dam burst and the deluge of water swept down and flooded the town (Johnstown, PA) downstream.

So again, stretching-the-rubberband-thin (as I often do):  periodical cicadas.  Eleven days ago (as I now write this), I observed and collected my first periodical cicadas — one here, one there, and so on.  Pretty quiet.  Four days later, I drove a gravel road with windows down —- listening listening listening.  In fact I would stop (to eliminate wheel noise) to listen.  And even shut the motor off to listen.  I would pick up cicadas calling from certain groves.

Three days later, the dam had burst.  That is, with windows down and driving 60+ mph, the wind blowing in my ears and the hum of the tires on-the-pavement road were not enough to drown out the LOUDNESS of periodicals from both sides of the road.  Also, more and more people have become aware of and reported periodicals now that (probably) the greatest percentage of their emergence has occurred.  While I have taken images of what I thought were impressive numbers of periodicals, nothing compares to those which I received from Ron Embry/Sarah Jaster at the Webster Conference Center, Salina, KS.   This brought to my mind an acronym that I use on occasion: TMTC = Too Many To Count!  While not useful for inserting into any formula for purposes of scientific statistical analyses, it serves to satisfy me in terms of relating uncountable numbers.  You be the judge.

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Periodical Cicadas Out in Full Force

Posted on by Sharon Schroll

–Dr. Robert Bauernfeind

The past two weeks have been filled with reports regarding the wide spread occurrence of 17-year periodical cicadas (refer back to Issues #4 and #7 of the 2015 Kansas Insect Newsletter for basic background information on periodical cicadas).  I am appreciative of those individuals who responded to my request for information/reports/observations of periodical activities in their respective counties, and super-appreciative for specimens submitted to me as well as photographic images.  For the remainder of my inclusions in this week’s Issue #8 of the KIN, I am including several images of periodical cicadas.

 

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An old friend revisited – Wooly maple/briar aphids (WMBA)

Posted on by Sharon Schroll

–Dr. Robert Bauernfeind

An old friend revisited – Wooly maple/briar aphids (WMBA)

It has been a number of years since I have had occasion to address wooly briar/maple aphids.  And matching dates of past encounters, the timing is right on (in 2007, June 1, and in 2009, May 29).

 

The inclusion of two very different host plants might have a person asking, “Well, are they on maple or are they on briar?”  In fact, both a primary woody host (maple) and an unrelated secondary/alternate herbaceous host (brier) are required for these aphids to complete their seasonal life cycle.

 

Despite their rather simple and familiar appearance, some aphid species (such as wooly maple/brier aphids) have very unusual and complex reproductive adaptations.   While most people are aware that the aphids which they encounter in their gardens and landscape plantings are all females which (in the absence of males) reproduce parthogenically by giving birth to living offspring, sexual forms are required for mating purposes and the eventual production of overwintering eggs.  This is where maple trees come in —  where (in the Fall) WMBA deposit overwintering eggs.

 

Thus, beginning in Spring, each 1st generation aphid emerging from an overwintered egg is a wingless female called a fundatrix (foundress-of-a-colony).  The offspring of each succeeding generation (all females, called fundatriginae) also produce living young.  These aphids eventually become overcrowded as they colonize twigs and branches.

 

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While the above-pictured aphids appear to be “normal aphids”, they aren’t called wooly aphids for no reason.  That is, these aphids possess specialized wax-producing glands.  And at some point, they will begin producing white flocculent strands which provides them with their “wooly appearance”.

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While not being sure of the exact stimulus at work, at some point, possibly overcrowding and constant touching/bumping-into-each-other “triggers” an internal response mechanism promoting wing production in developing aphids.  By mid- to late June, those aphids (again, all females which are now called exules) emigrate from their woody maple host to their alternate herbaceous host which, in Kansas, would likely be the plentifully-abundant greenbrier.

Upon reaching the summer host, exules deposit their offspring (you guessed it, all wingless females) which in turn account for additional summer generations on their briar hosts.  Upon entering Fall, shortened daylight hours hourst, decreased temperatures or a combination of both set off another change in aphid forms (now called sexuparae) of which there are two types:  Gynoparae are winged females which emigrate back to the primary host where they produce wingless females called oviparae;  and androparae are winged females which emigrate back to the primary host where they produce wingless males.  Males mate with oviparous females which then deposit the aforementioned fertilized overwintering eggs.

Now to the discussion on wooly maple/briar aphids that most readers care about.  Are they harmful?  Is there a need to control them?

The only real complaint leveled against wooly maple/briar aphids revolves around the “sticky mess” which they are responsible for.  WMBA congregate on the twigs and branches of the different varieties of sugar maples.  They insert their piercing-sucking mouthparts into the phloem elements which conduct the flow of plant juices/sap.  Fairly stationary, aphids continually withdraw the sugar-rich sap.  The excess juices are eliminated/excreted in the form of “honeydew”.  The honeydew “rain” will coat anything beneath WMBA-infested  trees  — vehicles, sidewalks, driveways, house decks, picnic/patio furniture, children’s swing sets and toys, items on clothes lines, and so on.  Being sticky and nutrient-rich, captured airborne fungal spores can proliferate into unsightly accumulations of dark-colored sooty mold.  But other than that, trees easily withstand wooly maple/briar aphid infestations as seen below.

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While insecticidal sprays and/or the use of forceful water sprays might seem called for, neither is practical in practice.  And, unnecessary!  By the time such infestations are discovered, within a very short period of time (2 weeks, possibly less), as described in the prior explanation of their seasonal developmental cycle, they will quickly dissipate on their own when they seek out their alternate summer host.  IT IS HIGHLY UNLIKELY THAT THEY WILL FIND THEIR WAY BACK TO THE SAME TREE HOST FROM WHICH THEY IMMIGRATED —- at least by my experiences/inspections.

Maybe one last-and-legitimate gripe:  handle with care.  They do leave a hard-to-remove stain that might relegate good clothing to a wear-only-at-home status.

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So Far, Sloooooow Going – Periodical Cicadas

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

Whereas the current cool weather and rains have been a boon to farmers and stockmen (think wheat and farm ponds) across the state, the explosive emergence of Brood IV periodical cicadas has yet to happen. I have visited several sites in and near the Manhattan area —– all has been silent.

I have received a report from Robert Hoard in Topeka where (as he arrived at work) last Monday, May 18, he noted emergence holes and cast skins (exuvia) in a flower bed next to his parking lot. The likely scenario is that the periodicals emerged some evening(s) between Friday through Sunday when daytime temperatures were high 70’s and low 80’s. Although he has yet to see any adults, they are likely nearby, lying low, perhaps hidden in and under the dense plant foliage.

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In order to somewhat quickly determine a rough estimate of numbers of emerged periodicals, Robert placed a 1 m2 grid over a portion of the flower bed —- counting 53 holes over a smaller sub-grid area. It will be interesting keep this area under observation to see if what initially emerged was just the tip of the iceberg for the 1 m2 area. (This image can be greatly enlarged should you choose to do so — an exercise for making a full count. An extrapolation could then be performed to obtain the estimated number of periodical cicadas per/hectare —– or if to be more meaningful, convert to a per/acre basis).

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Looking at the projected mid-to-high 70s/low 80’s for Memorial day through next Saturday, periodical cicadas should begin popping out like popcorn in a popcorn maker. I would appreciate my phone ringing off-the-wall (yes, still a land-line user —- 785-532-4752) as well as e-mail messages (rbauernf@ksu.edu) reporting periodical cicada activities. I would especially be appreciative of reports from the counties in yellow, orange, blue and pink.

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Feeding Capabilities/Capacities of Caterpillars – Useful Information for Bagworm Control

Posted on by Sharon Schroll

–by Dr. Bob Bauernfeind

The following basic developmental sequence is applicable to caterpillars regardless their species.

Beginning at egg hatch as a 1st instar larva, a caterpillar progresses through a series of developmental instars until such time it has matured, after which it ceases feeding when ready to transform into its pupal stage. In this sequence as determined under controlled conditions, the variegated cutworm consumed 442.2 mg of artificial diet. Only a small portion (27%) of the diet was consumed through the first 6 instars. In real situations where larvae feed on plant foliage, “nibblings” go unnoticed and are inconsequential. People usually first become aware of the presence of foraging caterpillars as foliage rapidly disappears when caterpillars ravenously feed midway-towards-the-end of their final “chow hound” instar. The last instar consumed 73% of the total diet.

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How can this information be applied to bagworm control? In the following sequence, in Weeks 1 – 5, under the green “safe” line, bags and bagworms are small. At 6 and 7 weeks, they become larger but remain under the yellow “still safe” line. Beginning at weeks 8 and 9, we have the orangish “amber alert” line. To this point, ALL ARE NIBBLERS! In weeks 10 and 11, we are under the red “danger” line as the bagworms now are into their “CHOWHOUND MODE”!

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When bagworms hatch in any given year, the hatching period occurs over a 4 to 5 week period typically beginning in mid-to late May. While it is informative to know when bagworm activities begin, that should not signal the beginning of automatic weekly spray treatments. Rather, a single thorough treatment (with a contact insecticide) applied at the end of June into the first 10-14 days of July should suffice. I enlarged and bolded thorough to emphasize the importance of not merely hastily-applying a light spritzy/misty spray treatment. While such might eliminate bagworms on the periphery of a tree/shrub, bagworm populations located in the more dense inner regions will be least affected. And as insecticide residues dissipate/degrade on the outer foliage, the unaffected bagworms will eventually move out and feed unfettered.

Comes the question regarding product/insecticide-of-choice. Currently in Kansas, there are 400+ products registered for use on bagworms. I personally do not recommend any one product over another. Use any contact insecticide (locally available through retail outlets) with bagworms listed on the product label. Based upon my experiences/trials (the first dating back to 1989), I achieved near-equally effective kill against late-instar bagworms using discontinued active ingredients (chlorpyrifos, diazinon, dimethoate, parathion) as well as currently available acephate, bifenthrin, carbaryl, cyfluthrin, gamma-cyhalothrin, malathion, permethrin, spinosad and trichlorfon. Reemphasizing: what is critical/key is not the active ingredient but rather (again) THOROUGH COVERAGE of the ENTIRE tree/shrub!

 

 

 

 

 

And Still Talking About Ash Trees – Brownheaded Ash Sawflies

Posted on by kansasbugs

—by Dr. Bob Bauernfeind

Based on reports posted by Department of Entomology Diagnostician regarding her having received specimens of adult brownheaded ash sawfly, I went out to a site where ash trees have been heavily infested the past couple of years. And, they are back. Though from a distance all appears normal, upon closer look, “pinhole feeding” is underway. By enlarging the image, the still-wee-larvae responsible for the “nibble holes” can be easily seen.

To treat or no-to-treat becomes an individual’s decision. Should trees become defoliated, they will rapidly recover, producing a flush of new foliage.

Brownheaded Ash Sawflies