Uninvited Holiday Guests

Insects, like all animals, must survive the winter (in one way or another) to reproduce the next year. There are two main strategies to do so: migrate or "hibernate". Of course there are famous insect migrations including monarch butterflies (Danaus plexippus) and several species of dragonflies (Odonata). However it is much more common for insects (and other arthropods) to hunker down for the winter in a nice secluded place. Insects overwinter in different life stages - either as eggs, larvae/nymphs, pupae (if they are holometabolous), or adults. The stage that overwinters usually depends on the type of insect, but sometimes can be determined by environmental or geographical factors.

Thus, as the days begin to cool and darkness descends earlier in the evening this holiday season, you may be getting more than your in-laws invading your home. Most do so by finding a nice brightly-colored home as a landmark during warm days where they aggregate on the siding, in eaves, or along windows. The most common nuisance insects overwinter as adults that may become active within homes during warm days of the season - a common occurrence here in NC which has a mild, fluctuating winter. Mass movements of these insects into living areas can be difficult to deal with and are a real annoyance. The following are some of the more common insects to enter houses.

- True bugs (Hemiptera) - the worst offenders -

Kudzu bugs aggregating in the crack of a tree; could easily be a window or the gaps in the siding of a house.

Bugs are among the most common insects found aggregating on and entering homes in the cooler months. Their numbers and the pungent smell they produce (they're not called stink bugs for nothing!) can be bothersome to people that want to enjoy the comforts of their indoors. Although bugs are generally harmless, kudzu bugs (Plataspidae: Megacopta cribraria) are sometimes known to cause irritations on skin, brought about by the secretions they produce. Brown marmorated stink bugs (Pentatomidae: Halyomorpha halys), another recent introduction into the US, also find it nice and cozy in houses. Along with these invasive bugs, many other types, including leaf-footed bugs (Coreidae: Leptoglossus) and boxelder bugs (Rhopalidae: Boisea trivittata), enjoy breaking and entering for a nice place to hibernate.

Kudzu bugs: one is alright, but hundreds are bad news!

Brown marmorated stink bugs find your home when it's cold outside.

Leaf-footed bugs may be seen around the home.

- Flies (Diptera) - can we use your attic? -

Figure from Oldroyd's magnificent book, The Natural History of Flies (1964). 

Several groups of flies will spend the winter in attics, barns and other man-made structures, safe and cozy away from the elements. The most common are called cluster flies (Calliphoirdae: Pollenia sp.), named for the fact that they often "cluster" in groups of hundreds in the attics of homes. Normally they are out parasitizing earthworms, but in the fall and winter when things slow down they get the urge to swarm homes. Face flies (Muscidae: Musca autumnalis) will also do this, usually around areas with livestock, their primary food (larvae live in dung and adults feed on facial secretions). On warm days these flies may come out of hiding to stretch their wings, much to the dismay of homeowners.

Cluster flies are drab (for blow flies) and have golden hairs on their thorax.

- Ladybugs (Coccinellidae) are pretty - but get them out of my house! -

"Ladybugs are great, right? They eat all the pests and are nice to look at." Tell that to someone whose living room is overrun by these red and black beasts. Most ladybugs do a fine job of staying outside and being good neighbors. However, one species in particular (though there are a few others) - the multicolored Asian ladybug or harlequin ladybug (Coccinellidae: Harmonia axyridis) - loves to come into homes. This highly variable species was first introduced into the US in 1916 for the control of pests and has been readily available for farmers and homeowners to purchase. In the 1980s it finally became established, and is now the dominant ladybug in much of its range. Thus there have been some concerns about this species. First, it may be pushing out native ladybugs with its voraciousness, which is not good for our biodiversity. Second, it can be structural nuisance pests. Along these lines, when they do enter homes in large numbers they can sometimes bite people and, like many ladybugs, reflexively bleed a noxious substance that may cause skin irritation and allergic reactions. For both of these reasons, the cartoon-like insects can be less funny than they are nightmare inducing.

Multicolored Asian ladybugs, though sometimes beneficial, are often a nuisance.

- So what can you do about it? -

The best way to deal with these insects is to first make sure that they cannot enter your home. Search for cracks and holes in the siding or under eaves. Any crack or hole small enough for the average insect to enter should be repaired or covered. While pesticide sprays on the South sides of the home may kill or deter some insects, they are not long-lasting, nor are they particularly effective. Once in the home, it is best to vacuum the insects up and collect them into hot soapy water or freeze to kill them. Spraying indoors usually does more harm than good, so cultural practices mentioned above work best.

About that pumpkin....

So Halloween has come and gone, but it's still Fall (Thanksgiving's on the way!) and everything is already red, yellow and orange. Why not keep that pumpkin spirit going?

Happy pumpkins are just glowing! (Photo by Matt Bertone)

Unfortunately, chances are by now your pumpkin is looking more like this:

This pumpkin used to be happy. (Photo by Sara Prado)

If you're lucky you can get it to the trash or compost without the bottom falling out (I wasn't that lucky). Even if you didn't carve a scary face in it, it will likely be in decline seeing as it is a fruit off the vine and it is slowly being broken down by bacteria and fungi. If there is a wound on the pumpkin from rough transport, it opens the pumpkin to these microorganisms. This is prime food for many insects that love to eat the nutritious soup.

Most of these insects are flies. Flies love rotting vegetable matter. Vinegar or fruit flies (Drosophilidae) are particularly fond of rotting fruit. Some walk all over their giant bounty, waving their patterned wings around while seeming to dance. They do this to attract mates and establish that they have found a nice source of food for their precious little maggots.

This vinegar fly (Drosophilidae: Chymomyza amoena) may have a dance party on your over-ripe pumpkin.

Other common flies include dark winged fungus gnats (Sciaridae) whose larvae love to eat the molds and other fungus growing happily on the pumpkin flesh. The small black flies swarm around the pumpkin and settle after a disturbance.

A mating pair of dark-winged fungus gnats (Sciaridae) - a scene you may see on your rotting pumpkin.

Many other fly species may be found among the decaying Jack-O-Lantern as well. However, flies aren't the only visitors to such a great source of food. Beetles, earwigs, isopods (sowbugs & rolly-pollys), slugs/snails, and other organisms like this type of substrate to feed on as well.

Picnic beetles (Glischrochilus) and other Nitidulidae love rotting vegetation. This is from last year's pumpkin.

Isopods may nestle themselves inside or under the pumpkin to feed.

"I am looking for a nice moldy pumpkin pie" says the snail. Slowly, he might find yours....

Of course, if you are responsible and discard your pumpkin while it is still fairly fresh, you won't have to deal with these insect and other small animals. But then again you may not see some of these cute little critters setting up shop and recycling your autumnal fruit festivity. Oh well, they can find the compost bin too I guess...

Pesky Blackberry Foes

Here in North Carolina, blackberry season is in full swing! For many North Carolinians, that means it is the perfect time to stock up their freezer or pull out those ball jars and can up some tangy black berry jam. Blackberry season brings back sweet summertime memories of riding my bike down the road to the black berry thicket at the edge of the woods, gorging myself with fresh, juicy berries (probably picking up a few chiggers in the process), and heading home with purple stains on my hands, face, and clothes. Whether you prefer to pick your own berries or buy a pack from the local Farmer’s Market, we can all agree that blackberries are a signature snack for a late summer’s day. Unfortunately, blackberries, like all things delicious, come with their fair share of pests and diseases that impact fruit production.

This summer, we have seen two similar but different diseases on blackberry samples: orange rust of blackberry and black raspberry and leaf and cane rust of blackberry. Orange rust is typically the more devastating disease because it can become systemic, moving from leaves into other parts of the plant. The orange rust fungus has two forms, Arthuriomyces peckianus (formerly Gymnoconia peckiana) and Gymnoconia nitens, which differ only in the number of spore stages produced. Pustules full of orange-yellow spores develop on the undersides of leaves in late May and early June. These spores are blown to healthy leaves and infect when humidity is high and leaves are wet. Heavily infected leaves may die and defoliate. Once the plant is infected, the rust fungus becomes systemic. It grows down the infected shoot, into the crown, and then can enter newly formed roots. Symptoms associated with shoot infections include proliferation of shoots, weak and spindly canes, and lack of spines on the shoots. In mid- to late summer, brownish black pustules that contain dark teliospores develop on the undersides of lower leaves. Teliospores do not infect, but germinate to produce basidiospores that can infect new buds or shoots, or the teliospores can overwinter on leaves before producing basidiospores the following year. Infected plants remain infected throughout their lifetime and do not recover.

Orange rust pustules on underside of leaves. Note leaf distortion. (Photo: PDIC Database)

Orange rust does not kill the plant outright, but infected plants are completely lost to production due to their inability to produce blossoms and berries. Controlling orange rust is largely achieved through cultural practices. Plant disease-free stock plants, eradicate diseased plants and wild berries in the surrounding area, and completely remove and destroy the entire plant as soon as symptoms develop on canes or leaves. Thin healthy plants to promote air circulation and to reduce leaf wetness.

Leaf and cane rust is caused by the fungus Kuehneola uredinis. Leaf and cane rust produces yellow spores in pustules that split the bark of infected canes, causing them to become weak. The pustules can also be found on the undersides of leaves. Diseased old canes should be pruned after fruiting. Alternate-year fruiting programs can help reduce disease pressure, and routine fungicide spray programs may be effective in preventing new infections. 

Leaf and cane rust. Note yellow spores bursting from cane. (Photo: NCSU Database)

Leaf and cane rust.  Infected leaves maintain shape unlike
those infected with orange rust. (Photo: NCSU Database)

Care must be taken to differentiate systemic orange rust from leaf and cane rust because leaf and cane rust does not require drastic removal methods to control disease. Identification of the rust pathogen requires a microscope and considerable knowledge in rust morphology. Suspect samples should be sent to the Plant Disease and Insect Clinic for a formal diagnosis.

LBJs (Little Brown Jobbies): Beetle Edition

The strikingly patterned eyed click beetle (Alaus oculatus) (Cary, NC).

It would be nice if all arthropods were as distinct as eyed click beetles (Alaus oculatus; above), harlequin bugs (Murgantia histrionica)  or black and yellow orb weavers  (Argiope aurantia). Although it would put me out of a job, it would also allow the public to better understand what insect, spider or millipede they are looking at in their garden or on their kitchen counter. 

Alas, many arthropods are difficult to identify or even impossible, especially just looking at them briefly. For example, in some species the male genitalia is the deciding characteristic - this makes female specimens unidentifiable to species or even genus. Others have many look-alikes or have not been well studied enough to find diagnostic traits to separate species. While these organisms may be very easily identified by experts, the public has very little chance of coming up with a name for the creature in question.

Some groups, however, are like black holes even to experts. I am sure every diagnostician can think of the group or groups in their field that have this characteristic. Among arthropods, I can think of a few: 

• small to medium brown moths (Lepidoptera)
• acalyptrate flies (most Cyclorrhapha)
• many small, parasitic wasps (Chalcidoidea & Platygastroidea)
• ground "sac" spiders (Clubionidae, Corrinidae, Gnaphosidae, Miturgidae...)

These groups share one thing in common: they all have many members which cannot easily be told from one another superficially, or at the very least from just looking at a photo online. 

The idea of blogging about this came to me last week when I got two samples into the clinic with superficially similar little brown beetles (another of these tough groups, and probably one of the most difficult).

Can you tell them apart? LBBs (Little Brown Beetles) representing 3 families and 2 superfamilies. Left - Mycetophagidae: Typhaea stercorea (Tenebrionoidea); Middle - Silvanidae: Ahasverus sp. (Cucujoidea); Right - Erotylidae: Cryptophilus sp. (Cucujoidea). All from North Carolina, USA [Photo by Matt Bertone]

One species (above left) was from garlic that had been left in a barn to cure after harvest. The other two (above middle & right) were found as adults and larvae in alfalfa hay. All three beetles were likely attracted to the fungus that was growing on these drying products which probably grew mold due to the humid and rainy weather we have been getting. All three are functionally similar, but taxonomically very different. There are over a dozen such families of small, brownish beetles that act very similar, infesting stored products, dried wood, and moldy areas (just look at some Cucujoidea to see how similar some are). Many are thus associated with human homes and product facilities where they feed either directly on the grains or on the microscopic molds that coat these products. Not only are they difficult for the layperson to identify, but most are also small to extremely small, making ID even more difficult:

Actual size of the beetles shown above. The largest (Left) tops out at just under 3 mm long! [Photo by Matt Bertone]

In the end, these arthropods are what keep people like me busy looking at them under a microscope at 70X magnification, counting the number of segments in their feet...

Fairy Rings and Fairy Tales

written by Lee Butler, NC State Turf Pathology

Fungi love water and here lately in North Carolina we've had plenty of water via record rainfall to help ensure they don't go extinct any time soon. The majority of fungi in this world are beneficial, because without these fungi we wouldn't have some of the finer things in life such as beer or Agaricus bisporus that adorns salads and pizzas as a topping. However, there are plenty of them that cause problems for us in the form of plant diseases.

Fairy ring mushroom (Photo: B. Shew)

You name a disease of turfgrass and we have likely observed it in the field or as a sample submitted to the NC State Turf Diagnostics Lab over the past 3-4 months. One that we rarely receive as a sample due to it's ease of identification is from a fairy ring. Most people associate fairy rings with mushrooms. To quote NC State alum Dr. Lee Miller, "not all fairy rings produce mushrooms and not all mushrooms produce fairy rings." This is important to remember, because if you observe mushrooms in your lawn, putting green, or croquet court, it doesn't necessarily mean you have a fairy ring problem.

A fairy ring in Raleigh, NC (Photo: Lee Butler)

Fairy rings have likely peaked the interest of mankind since day one. This fascination has led to some crazy theories over the years such as fairies danced there the night before or that it was created by the fiery tail of a flying dragon. Whatever you do, don't step into the ring, collect the dew from the grass blades, or attempt to destroy it because bad luck is guaranteed to follow!

"Plucked from the Fairy Circle" - A man saves his friend from the grip of a fairy ring.
From British Goblins: Welsh Folklore, Fairy Mythology, Legends and Traditions (1880)

Fairy rings tend to form in circles, arcs, crescents, or broken rings. During their radial journey outward, fairy ring fungi decompose organic matter, which in turn releases nitrogen and other nutrients back into the soil for plants to take up. This is why the ring will often be darker green than the surrounding turf. The good news is that fairy ring fungi don't actually infect the turfgrass plant like brown patch, dollar spot, etc. The bad news is that they leave behind a coating on the soil particles that renders the soil hydrophobic (repels water) and may ultimately kill the turf. This is important to know when it comes to controlling the symptoms caused by fairy rings. For example, if you are treating fairy rings curatively in a home lawn situation, your best bet may be as simple as punching holes through the dead rings with something as fancy as an aerification machine or as simple as a pitchfork. Either way, you are instantly helping water penetrate the affected zone. If you are only observing green rings, then you may be able to mask them with a light fertilizer application. In severe cases or in high profile areas, you will likely want to use wetting agents and/or fungicides in addition to the aforementioned tips.

Fairy Ring on NCSU Campus (Photo: B. Shew)

For more information about fairy rings, including control recommendations, click here.

Late Blight Has Arrived

Over the past 2 weeks, late blight, caused by Phytophthora infestans, has been knocking on the doors of our state. Aided by the monsoon-like weather we’ve been experiencing the past few weeks, our unwelcome guest has finally managed to get inside and start to wreak havoc. Late blight was officially confirmed on tomatoes from Guilford County on July 2nd. Today we diagnosed late blight on a tomato sample from Wake County and on a sample of tomatoes and potatoes from Watauga County.

Late blight can be a devastating disease on tomatoes and potatoes. Without proper preventative measures, late blight can completely defoliate and destroy a crop within one to two weeks.

The first symptoms of late blight on tomato leaves are irregularly shaped,
water-soaked lesions. (Photo: K. Ivors)

More information about tomato late blight and how to control it can be found in this tomato late blight factsheet produced by Dr. Kelly Ivors and in our earlier blog post. 

More information on potato late blight and how to control it can be found in this potato late blight factsheet produced by Dr. Lina Quesada-Ocampo.

Videos and additional management recommendations for tomato and potato are available in the USAblight website. Here you can track the late blight epidemic and register to receive text and/or email alerts when new disease outbreaks are reported.

Blame it on the rain (Part II): Reprise of the slime molds

An aerial view of a grove of strange trees? Read on.

With all this wet weather we can expect to see a lot of plant diseases in the upcoming weeks. Oddly enough, damage due to root rots won't be evident on trees and shrubs until the weather turns hot and dry. That's when the damaged root systems won't be able to keep up with the demand for water in the foliage. All this is a story for another day, however. Today I want to revisit a group that was a blog topic two years ago: the slime molds. (See our archived post.) These are sometimes called myxomycetes, but don't let the Greek suffix fool you; they are not related to true fungi.

Stemonitis sp. (Photo: Matt Bertone)

We had several inquiries about slime molds during the last week of May. Fortunately they do no harm to plants, animals, or people, though some folks have been shown to be allergic to the spores. One inquiry was accompanied by a spectacular photo - not reproduced here - of Diachea leucopodia on grass blades. Another was the specimen of Stemonitis - probably Stemonitis fusca - pictured at right. It had been picked up off of a living room baseboard. This particular slime mold is usually associated with wood, sometimes indoors. The photo at the top of this blog was taken on a stump in Schenck Forest in Raleigh several years ago. In both pictures you can clearly see the thin "stipe" or stalk that supports each cylindrical spore-bearing "sporangium".

Remnants of slime mold fruiting on Japanese holly

A third specimen from that same week was submitted by one of our campus landscapers. She was concerned about white material on the foliage of a Japanese holly. This turned out to be another slime mold. Most of the sporangia had broken off, but a the base (called the hypothallus) was still stuck to the leaves. This particular case is covered in the "Geeks Corner" below.


Then yesterday while out looking for leaf spots on maples, I noticed some whitish gray tufts in a mulched bed in the shade of several trees. It turned out to be yet another slime mold, Acyria cinerea. The tiny sporangia are only about a millimeter-and-a-half tall, not counting the stipe. If you look closely, you can see that they are often in clusters.Within these sporangia, the white spores are held by a network of spiny threads called a capillitium. The characteristics of the capillitium are important in slime mold identification.

Capillitium and spores of Acyria cinerea at 400x.

Fruiting of Acyria cinerea on mulch

What we are seeing in all these cases is the end-game of the slime mold's life cycle. If the wind-dispersed spores land and find the right conditions they'll germinate into ameoba-like cells that will eventually become a multicellular, macroscopic, living film called a plasmodium. This plasmodium will slowly "crawl" or ooze around on wood or bark, in leaf litter, on dung, or on other materials. They almost always escape notice at this stage, during which they "feed" by engulfing bacteria, fungal spores, and probably  bits organic matter. Eventually the plasmodium switches gears and changes over to spore production, treating us to one of nature's great works of art. The Georgia Museum of Natural History has posted a gallery of myxomycete images by photographer Ray Simons.

Fruiting of Fuligo septica

Not every member of this group is quite as lovely. Fuligo septica, the "dog-vomit" slime mold, is gross in both the German sense of "large" and the English sense of "repulsive". It is very common on hardwood mulch and was highlighted in our June 14, 2011 blog. When the plasmodium first comes to the top of the mulch and before becoming a crust-covered mass of spores, it's basically a bright yellow froth. A picture of a more mature fruiting is shown at left. Up close, they don't look so bad, actually.

Sporangia of what is probably Physarum leucopus.
The width of this photograph covers only a quarter inch.

Geeks Corner. The slime mold pictured at right baffled me for a while. As a non-expert in this group, I was having trouble deciding whether there was lime in the capillitium or not. There are clearly lime deposits on the peridium (outer covering), giving it a frostly look. Using Martin & Alexopoulos's 1969 tome The Myxomycetes, I eventually keyed it out to Physarum leucopus. The reference states, "Before the peridium breaks, this species is remarkably similar in appearance to Didymium squamulosum." The key distinctions: white nodes in the capillitium, the lack of a columella, and the fact that the lime on the peridium exists as granules rather than crystals.


For anyone interested in learning more, I highly recommend starting with Stephenson & Stempen's book Myxomycetes: A Handbook of Slime Molds (1994. Timber Press).

Blame it on the rain (Part I): A multitude of millipedes

In the last couple weeks we have gotten a lot of rain. This can have both positive and negative impacts on pests and pathogens. One critter I have been getting a lot of calls and emails about is the greenhouse millipede, Oxidus gracilis (Polydesmida: Paradoxosomatidae).

The greenhouse millipede (Oxidus gracilis) is one of the most common arthropods around. It can be distinguished from other millipedes by the size (~1"), brown color, and especially by the groove going across the top of each body segment
Photo by Matt Bertone

Millipedes are in a group of organisms, closely related to insects and spiders, called myriapods (which translates literally to "many-legs"). At first they may appear to be worms, but they have legs which worms lack. The most familiar are centipedes and millipedes, some of which grow to large sizes (some tropical centipedes are a foot long and can eat bats, lizards and rodents!!). While centipedes are carnivorous and have venom, millipedes are vegetarians that feed on decaying plant matter. Though they cannot bite, many millipedes defend themselves with toxic poisons that either taste bad or can cause sickness - but only when eaten. This is the reason why some millipedes you see are brightly colored and smell like almonds (related to the cyanide compounds they produce):

A larger relative of the greenhouse millipede (Polydesmida: Xystodesmidae) [~1.5" long]
Photo by Matt Bertone

The greenhouse millipede is a non-native species from Asia that has traveled throughout the world with humans. They are abundant under rocks and logs, in basements and in the soil - anywhere where there is some moisture. People tend to notice them sporadically until some event drives them out of hiding. In the case recently, our heavy rains from multiple storms have saturated the soil and make it difficult to survive for the millipedes. Their response is usually to move to higher ground like the foundations and walls of homes and other structures. They may even move inside, though if they get stuck it's bad news for them as they will inevitably die, and bad news for homeowners who have to clean up the carcasses and deal with a distinct odor they produce. In addition, their movement can sometimes be caused by them avoiding chemicals/pesticides that have been sprayed around their habitat, especially the mulch and gardens next to homes.

Greenhouse millipedes invading people's space.
Photo from Stokes Co., NC

Control, especially in the chemical sense, is usually not warranted. Simply vacuuming up the critters is often enough to get rid of them. They pose no harm to people and little to no harm to plants (sometimes becoming important in greenhouse situations - hence the name). So if you are seeing a lot of these worm-like organisms after rains or chemical treatments, be aware that the situation is (A) temporary and (B) the millipedes are harmless (some large ones even make great pets!).

Quick guide to centipedes and millipedes (and other look-alikes):

Does it have legs? 

> If not then it is likely a worm (though some maggots and other critters are similar):

Typical earthworm.
Photo by Matt Bertone

> If yes, but only up to six true, jointed legs (all on thorax) then it is an insect, likely a larva (caterpillar, grub, etc.):

A click beetle larva (Elateridae) - note only the thorax region has true legs.
Photo by Matt Bertone

> If yes and many legs then you have a myriapod*!

(*unless you have an isopod - pillbugs and sowbugs)

BUT is it a centipede or millipede?

> If it has one pair of legs per segment and is generally fast-moving then it is a centipede (also see house centipedes):

A typical stone centipede (Lithobiomorpha).
Photo by Matt Bertone

> If it has two pairs of legs per segment and is generally slow moving then it is a millipede:

A granulate millipede (Polydesmida: Polydesmidae: Scytonotus granulatus)
Photo by Matt Bertone