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New Invasive Fruit Fly Pest

For the most recent updates posted by Highmoor Farm for Maine fruit growers, visit their latest blog posting.

Last Update Posted: 8/17/2012. The first Spotted-wing Drosophila of the 2012 season for Maine was found in a trap in Limington (York County) on Friday, July 13th.  Since that time, it has been found in traps at locations in Buxton, Springvale, Bowdoinham, Dresden, New Gloucester, Poland Spring, Mechanic Falls, Turner, Farmington, Wales, Litchfield, Fayette, Thorndike and Warren. During the final week of July, additional captures occurred in Buxton, Bucksport and Franklin, in addition to more captures at the earlier locations. In addition, traps in wild blueberry fields in Hancock and Washington counties have caught flies during the past week. At this point we expect that the fly is fairly widespread and active through most, if not all, of the southern, mid-state and coastal regions of the state. 

It is important to understand that the traps are unlikely to provide early warning, i.e. when we find them in a trap they are probably already established in that area and in that particular soft-skinned fruit crop.

Trapping / monitoring efforts for this fly are ongoing.

Report first posted December 8th, 2011
A new, invasive fruit fly pest, Drosophila suzukii, has spread into Maine.  It’s called the Spotted-wing Drosophila, or SWD for short.  It is an invasive insect from China & Japan, and was confirmed in Litchfield, New Hampshire on September 6th, 2011.  Throughout the months of September and October, it was confirmed at several locations in Maine (mostly southern Maine thus far) where traps were set out.  Confirmations were made in one town in Lincoln County, one town in Kennebec County, another town in Franklin County, and two towns in York County.   The SWD flies turned up fairly heavily in fall raspberries in three of those locations, strawberries in another location, and at a greenhouse tomato operation at a fifth location.  This fruit fly, in addition to the spots found on the wings of the males, is distinctive in that the females are armed with a serrated (saw-like) ovipositor for depositing their eggs, which means that ‘healthy’ fruit with an intact, unbroken skin, may not be immune from attack and even fruits with relatively hard skins have cause to be concerned, which is why plans are well underway to conduct extensive trapping throughout 2012 to try to get a clearer handle on what dangers Maine fruit growers might be facing from this new pest.

For more information:

a Spotted-wing Drosophila fruit fly (male) Spotted-wing Drosophila (new invasive fruit flies trapped in Maine) A pair of Spotted-wing Drosophila fruit flies -Male pictured on left; Female on right

Bug Reporter: Japanese Beetles & Potato Leafhoppers

a cluster of Japanese Beetles feeding on some leavesOur field ‘Bug Reporter’ has told us that Japanese beetles and potato leafhoppers are now active.  Here are some resources and/or fact sheets on each of these two important and economical pests:

Additional Photos:

Japanese Beetles Potato Leafhoppers

Late Blight News

Late Blight Photos / Symptoms

Late blight has very recently been reported in potato plantings in coastal Maine (Woolwich, in Sagadahoc County) and an additional outbreak was reported in Penobscot County. Late blight has also been reported in the St. Andre area of New Brunswick, Canada. Conditions for the development of late blight have been very good in Maine and growers should be on the alert to catch any early symptoms on their plants and be ready to apply appropriate control measures. Typical symptoms will be water-soaked lesions on the leaves with fine, white cottony mycelium on the undersides. Infections on the stems appear as dark, almost black lesions.

Late blight spores can travel over 40 miles under the right conditions (wet and warm) and the spread can be very fast. We are encouraging all growers to carefully and regularly inspect their plants for this disease. Please report any suspicious symptoms to us at our UMaine Extension Pest Management Office at 207-581-3883 or 1-800-287-0279 (in Maine) or e-mail Bruce Watt, our Plant Disease Diagnostician ( Samples should be sent in a sealed plastic bag with a dry paper towel to keep them fresh. Visit for more detailed shipping and sample preparation directions, as well as a submission form for any samples you send to us.

More information about Late Blight:

European Chafers

European Chafer beetles are now active in the Bangor region of the state (and have likely been out for a little while already in areas south of Bangor).  The adult is a 1/2 inch long, golden tan to light brown, oval-shaped June beetle [photo courtesy of USDA ARS].  These beetles emerge from the ground annually at this time of year (June & July), just as it is getting dark, and take off in search of eligible mates.  Females begin laying eggs (in the soil) just a day after mating, and the eggs hatch in 2 to 3 weeks into tiny white grubs–the destructive stage of this pest–which begin feeding right away on grass roots.  The grubs continue to feed on the roots of grasses throughout the summer and again the following spring, chewing them off and killing the grass in the process.  So if you are seeing these beetles swarming in your area, and/or you have areas of turf that have been victimized in the past by this pest, now is the time to be preparing to take control measures, if that is on your agenda!

Detailed Fact Sheets: European Chafer (Purdue) – see also pdf (Cornell), and for more about the grub stage of this and other similar lawn and turf pest beetles, visit: White Grubs in Lawns (University of Illinois) and White Grubs in Home Lawns / pdf (Penn State)

Rose Chafers are also active now.

Eastern Tent Caterpillars

The silken/webbed nests spun by Eastern Tent Caterpillars are starting to be seen in trees now (early May).  These caterpillars feed on apple, peach, plum, crabapple and cherry trees and build distinctive nests in the forks of the branches. Feel free to review our fact sheet on these caterpillars for more information, including some things you can do to combat them (and how they differ from Forest Tent Caterpillars).

Additional Photos:

an EasternTentCaterpillar and an example of the communal nests they make in trees Eastern Tent Caterpillar - egg masses

Beetles and Grubs and Ticks, Oh My!

Spring is well underway, and here are some of the things getting some attention as of late:

  • Predaceous Diving Beetles: These beetles, in a family of water beetles called Dytiscidae–based on the Greek dytikos, meaning “able to dive” [in water]–are out and about now, and being noticed by some homeowners. They are nothing to be concerned about, however, and you can find them in the ‘Curiosities’ group of our Fact Sheets section, as they are indeed a source of curiosity for many people.  They show up sometimes in swimming pools, or in driveways or parking lots where it is suspected that they mistake the shiny surface of many automobiles for bodies of water, as is their natural habitat (i.e. they are aquatic, and have structural modifications ideal for swimming). When in water, they move their hind legs together like oars. Backswimmers also swim this way, but other aquatic beetles move their two back legs one at a time when swimming.  As their name implies, these beetles prey on other insects and critters–such as tadpoles–small enough for them to overpower with their short, but sharp, mandibles. The larvae (which stay in the water) are also predaceous, and are commonly known as water tigers (photo of larval stage).

a Predaceous Diving Beetle a Predaceous Diving Beetle a Predaceous Diving Beetle

Above: Some Predaceous Diving Beetles found in Maine.  Most Predaceous Diving Beetles are dark brown, blackish or dark olive in color. Some have golden highlights such as the one shown above (far-right).

  • White Grubs: We are getting a lot of white grubs brought in to our office for identification, the vast majority of which thus far this season are the European Chafer [MSU provides an excellent fact sheet on this critter and we are linking to theirs until we can add the finishing touches to one of our own].  Our insect diagnostician says he is seeing evidence of their feeding damage to grass in peoples’ lawns, cemeteries, etc. in the Orono & Old Town, and Bangor & Brewer areas now.  It seems that the European Chafer has had several profitable seasons in a row, and it may take an especially harsh (i.e. COLD) winter before we begin to see their numbers decline.  As it stands now, this pest seems to be on the rise, unfortunately.

May is Lyme Disease Awareness Month in Maine!! Know Ticks, No Lyme

[Text courtesy of the Maine CDC]: Lyme disease is the most common vector-borne disease in Maine.  May is Lyme Disease Awareness Month in Maine, so remember to do your tick checks!  With the mild winter, it is never too early to start thinking about tick prevention.

a deer tick (non-engorged) next to a US penny for scale purposes

Unengorged Deer Tick (also called Black-legged Tick) (UMaine Extension photo)

Lyme disease is a bacterial infection that is carried by Ixodes scapularis (the deer tick).  Maine had a record high number of cases in 2011, with positives occurring in all 16 counties.  Lyme disease is most common among school-aged children and middle-aged adults.  As the weather begins to get warmer, more ticks will be out in the open.  Most Lyme disease infections in Maine occur during the summer months.

Note from UMaine Extension: Visit the Ticks page of our Home & Garden IPM website for more tick photos (including pictures of other kinds of ticks):

The most common early symptom of Lyme disease is an expanding red rash that occurs 3 – 30 days after being bitten.  Fever, joint, and muscle pains may also occur.  Lyme disease is treatable, and the majority of patients recover after receiving appropriate therapy.

Lyme disease is a preventable illness.  Maine CDC recommends following the “No Ticks 4 ME” approach which includes:

1.    Wear protective clothing
2.    Use an EPA registered repellent:
3.    Perform daily tick checks
4.    Use caution in tick habitats

Ticks must be attached for at least 24 hours for the bacteria that causes Lyme disease to be transmitted, so prompt removal of ticks is extremely important.  Anyone with a known tick bite, or who spends time in a tick habitat, should watch for symptoms for at least 30 days after exposure.  If symptoms develop, call your healthcare provider.

Additional information:
Maine CDC has numerous educational materials available online at


Tar Spot Fungus

Tar Spot fungus on a maple leaf (click for a magnified view) (additional images below)

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As you may have noticed, many of the maple trees in the area developed unsightly black leaf spots over the course of the 2011 summer and foliage was turning brown and dropping rapidly.  The combination of the fungal pathogens ‘tar spot’ and ‘anthracnose’ caused this aesthetic damage to maples throughout Maine.

Tar spots, as the name suggests, are raised, black spots that form on the upper surfaces of maple leaves, not as the result of contact with actual tar, but due to a fungal infection.  Fungi from the genus Rhytisma, most commonly Rhytisma Acerinum, typically shows up on maples in late spring or early summer as light green or pale yellow spots.  As the season progresses, the yellow color intensifies and raised, black tar-like spots are formed within the yellow spots.

Tar spot alone is rarely serious enough to be detrimental to the overall health of infected trees.  However, as the infection progresses trees become unsightly and can experience premature defoliation.  If infected maple leaves begin to crinkle and turn brown, anthracnose, another common disease of maple, may also be present.

The fungi that cause tar spots and anthracnose overwinter on infected leaves that fall to the ground.  The following spring, the fungi produce spores which are carried by the wind and can re-infect susceptible foliage at bud break, if weather conditions are right.  The most effective management strategy is to rake and destroy infected leaves in the fall, thus reducing the amount of overwintering fungi.  The application of fungicides to control tar spot is typically not recommended because complete coverage of all infected leaf surfaces is necessary and can be extremely difficult as well as costly.

James F. Dill & Griffin M. Dill

early stage of Tar Spot fungus infection on a maple leaf Tar Spot fungal infection - pustules starting on a maple leaf Tar Spot fungus - coalescing stage on a maple leaf Tar Spot - coalescing advanced Tar Spot fungus - advanced stage Tar Spot (outdoors - showing leaves that have dropped, which is a side effect or result of the infection)

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Tussock Moth Caterpillars

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Tussock moth caterpillars (Family Lymantriidae) were very abundant in Maine in 2011 and they were ‘itching’ for attention! One reason for all the attention they receive (during late summer and early fall) is that, unfortunately, the hairs on these caterpillars can cause a very itchy rash.  The prickly hairs are a defense mechanism (they are NOT poisonous or venomous).  It is important to note that children are more susceptible to the rash than are adults, and children are also much more likely to be playing with them and handling these showy critters (natural curiosity/fascination/playing outdoors).   The rash from some of the members of this group tends to be short-lived, and clears up on its own after two or three hours.  For other species, however, such as the Hickory Tussock (white one shown below), the rash can be much more severe and long-lasting, and a doctor’s visit might be warranted to speed one’s recovery and ease the symptoms / discomfort.

see also: Bangor Daily News story (August 30th, 2011)

Some examples of Tussock Moth Caterpillars found in Maine (the hairs on members of this group can cause an itchy rash):

Picture of two different tussock moth larvae A tussock moth caterpillar (one species of several that are found in the Tussock family) Picture of a tussock moth caterpillar a Tussock Moth Caterpillar on a leaf Tussock Moth Caterpillar (Larva) -- this one is perhaps a Pale Tussock Caterpillar a Milkweed Tussock Caterpillar or Milkweed Tiger Moth caterpillar a Hickory Tussock Moth Caterpillar (Larva -- early stage) a picture of a Hickory Tussock moth caterpillar

a Brown-tail moth caterpillarNote: The caterpillar of the brown-tail moth is also a member of the Tussock family. [brown-tail moth] (Maine Forest Service)
Nest made by Brown-tail moth caterpillars


Late Blight News and Confirmations

Late Blight Photos / Symptoms

August 17th, 2011: The Maine Public Broadcasting Network Monday interviewed UMaine Cooperative Extension pest management specialist Jim Dill about new reports of late blight affecting potato plants in Aroostook, Kennebec and Androscoggin counties and tomatoes in Maine’s Mid-Coast areas. Damp, overcast weather helps spread spores from the fungus, which can devastate certain crops in a matter of days.

July 22nd, 2011 [Potato Update]: Potato late blight was found in one location in Central Aroostook County.  The infection was in the upper portion of the plants, indicating that the infection was the result of wind-blown spores.  Late blight has also been reported in Denmark, New Brunswick.

July 5th, 2011: The following states confirmed late blight (so be on the lookout): Maine, Michigan, Connecticut, Florida, New York, Delaware and Virginia. Conditions for the development of late blight have been very good in Maine and gardeners and farmers alike should be on the alert to catch any early symptoms on their tomato and/or potato plants.   Typical symptoms will be water-soaked lesions on the leaves with fine, white cottony mycelium on the undersides.  Infections on the stems appear as dark, almost black lesions.

More information about late blight:

Spring 2011

Late May Observation: Eastern Tent caterpillars have begun appearing in trees, along with their familiar communal tents. The young caterpillars feed on the buds, and the nests become apparent this time of year. As the larvae grow they begin to feed on leaves. When the population increases, it is not uncommon for trees and forests to be defoliated. The caterpillars mature in the first part of June, with adult moths appearing during the last part of the month, when egg-laying takes place. There is one generation per year.

The beginning of the spring brought large numbers of low-flying, solitary ground-nesting bees over many Maine lawns and flower beds.  These beneficial insects are good pollinators that are helping to fill the honey bee gap.  They are not particularly aggressive and their numbers will lessen as spring turns into summer.

Most of the white grubs that have been coming into our lab this spring from the Brewer, Old Town, Orono, and the Bangor area are European chafer grubs.  This species of white grub starts feeding earlier in the spring, feeds more aggressively, and feeds later into the fall, than the other species in the area.  The European chafer grubs have been quite plentiful in this area for the last three years.  Those desiring an organic approach for the management of the next generation of white grubs, may consider using beneficial nematodes, best applied during the last three weeks of August.  Preventive measures targeting the next generation of grubs, using conventional materials, would generally work best when applied in June and July.  Before using pesticides on your lawn, one should be knowledgeable about soil type and ground water protection and surface runoff patterns which may affect lakes, ponds, rivers and streams.

Once the weather warms and dries up we should have good numbers of black flies, especially near streams and rivers.  It should be noted that black fly populations are not always evenly distributed, but can be in localized dense swarms.   Personal protective tactics, such as limiting exposed skin and the use of repellents, are suggested for those involved in outdoor activities in high black fly areas.

We have had a number of deer ticks brought into the lab starting in April.  Please be sure to do tick checks after hiking, gardening, walking the dog, and other outdoor activities that may take you into the forest or brushy areas.

a deer tick (non-engorged) next to a US penny for scale purposes photo of a deer tick next to a dog tick (both are unfed or non-engorged, and both are beside a US penny for relative size comparisons) engorged Deer Tick (LEFT) beside an engorged Dog Tick (RIGHT) for easy comparison (the dog tick is significantly larger)

Clay Kirby
Insect Diagnostician

cartoon bug reporter