Occasional Invaders


I am having problems controlling silverfish in a residential account. The customer keeps complaining of silverfish in the master bathroom. I’ve treated the bathroom and looked around the exterior of the home but am not finding any evidence. What am I missing?

Silverfish rarely are found in high numbers. The infestations are often localized, so the best thing to do is find the source of the infestation and remove it. It sounds like you have inspected conducive areas outdoors and hopefully eliminated any debris, wood piles or other items that silverfish may harbor in close to the home. Next, I would turn your attention back to the inside of the house and identify any moisture or food sources. Silverfish are omnivores and will eat a variety of things, including glue, cardboard, paper products, dead insects and cereals. Be sure to inspect the basement and garage, as well as any attic spaces, because storage areas can have a lot of different materials that silverfish may be feeding on. Sticky traps can be placed around all of these areas to identify active areas and hopefully find the source of the infestation.

After a client complained of insect bites, I inspected the home and found several dozen mites that appear to be the cause of the problem. The client lives in a high-rise building, and has no pets. Where could these mites be coming from?

A common reason for mites infesting a home and attacking humans is because the mite’s normal hosts, often rodents or birds, are no longer available. With nothing else left to feed on, the mites will migrate from the host’s nest or burrow in search of another food source. Indoor applications using appropriately labeled products can manage mites that have already migrated from nesting sites. However, this strategy will not prevent re-infestations. The best control strategy is to eliminate nests and roosting areas for birds, or control the rodents.

I would start by identifying the mites. Knowing the species will point you in the right direction of what host to inspect for. If you have bird mites, search for any signs of roosting and nesting, especially on the exterior of the building around your client’s home. These signs can include nesting materials in rafters or ledges, and sites above where droppings have accumulated. For mites that infest rodents, look for droppings or other evidence of activity that could indicate a nesting site such as damaged goods and chewed insulation.

I have been battling clover mites at a nursing home for the past two years. I have tried several different products, but nothing seems to work. Any ideas?

Clover mites can be a tricky pest to manage, especially in sensitive areas where management options may be limited. They can reproduce quickly and feed on a range of plants including several lawn grasses, ornamental flowers, clover and dandelion. Luckily, there are a few IPM steps you can take to reducing their populations.

One of the most important steps to controlling clover mites is through prevention. Clover mites are attracted to shaded areas with lush vegetation where food sources are abundant. Work with your client to eliminate these areas around buildings to discourage populations from establishing on the property. Second, create a 18-24” plant-free zone along the foundation perimeter of structures to discourage clover mites from moving into buildings, and to provide an easily treatable area. Lastly, consider replacing some vegetation on site with plants that are not attractive to clover mites. These can include geranium, chrysanthemum, marigold and roses.

I keep finding springtails in my client’s bathroom, and cannot seem to find the source of the infestation. Is it possible that my client or their houseguests are bringing springtails into the bathroom on their clothes or other personal belongings?

Springtails are delicate little arthropods that require very humid conditions to survive, so houseguests bringing them in on clothes or other personal belongings is unlikely. Springtails naturally occur in damp soil where they feed on fungi and decaying vegetation. Heavy rains or dry conditions can drive large numbers of springtails indoors seeking shelter or moisture. They can even hitch a ride indoors in the damp soil of potted plants. Once inside, springtails must find a humid area where moisture is present, such as a bathroom. If your client’s bathroom shares an outside wall, an outdoor population of springtails may be accessing the bathroom through an overlooked crack or crevice. Springtails also could be breeding inside near a plumbing fixture, or in potted plants. Focus your inspection on identifying one of these possible sources and correct the issue. Drying out the area using a dehumidifier may also be necessary to achieve control. Once the source and any conducive conditions have been addressed, an appropriately labeled residual pesticide can be applied to eliminate any remaining adults.

Is there a “silver bullet” for silverfish?

Most pest management professionals will agree that silverfish are one of the more frustrating pests to control. Unfortunately, there is no definitive “silver bullet” for silverfish. As is the case with most pests, management often requires a combination of control strategies that are tailored to the behavior of the target pest. In the case of silverfish, understanding their feeding behavior is particularly important. Silverfish can feed on a variety of household items that contain carbohydrates or proteins, but they are mostly considered pests of paper. Silverfish are particularly fond of glazed paper goods that contain starch, dextrin or glue. This explains why they are often reported feeding on the glue of wallpaper, book bindings and cardboard. Silverfish may travel some distance to find food, but are less likely to leave an area when a food source is present. Their bodies are flattened, conveniently allowing silverfish to find harborage in food items such as book bindings, between loose pages of books and in the corrugations of cardboard. Removing or eliminating access to the above mentioned food sources will be important to controlling silverfish. This can be done by swapping cardboard storage boxes for plastic storage bins, and by storing paper goods in sealable containers. Dehumidifying infested areas, installing sticky cards and vacuuming cracks and crevices may also help to reduce numbers. In addition to non-chemical control measures, applying appropriately labeled dusts to cracks and crevices can control of silverfish seeking harborage away from food sources.

I have a client with a tremendous springtail issue.  I found most of the springtails along the foundation of the customer’s house about 2-3″ down into the soil.  She has some old mulch (of course holding moisture).  But the springtails are also getting into the house, and onto the tile floor of the basement and her kitchen countertop.  From my inspections, there are no moisture problems inside and it is a very clean house!  Do you have any suggestions?

We recommend that you rake back the mulch from the foundation by about a foot to let it dry out in those areas.  You may also apply some kind of material to the rake backed areas.  Does this customer have an automatic sprinkler system that waters daily or on a regular schedule?  This could be the issue.  Dry out the area and adjust the sprinkler timer to be less frequent.

If you are also seeing springtails inside, check for plumbing leaks around sinks and drains and bath trap areas.  Springtails cannot survive without moisture sources, and they often are good indicators of a problem plumbing issue.  Dry out the area with increased ventilation, fans and dehumidifiers and address the plumbing issue.  Various dusts may also be applied in wall void areas.  When using such a product, always read and follow all labeled instructions.

We are hearing reports about the kudzu bug and are starting to get calls about it.  What is the latest news on this pest and how can we control it?

The kudzu bug (Megacoptera cribraria) is an exotic invasive insect that was first observed in the United States in late 2009.  First reports of this insect were from northeast Georgia, where pest management professionals encountered large aggregations of the bug on the sunny, south-facing sides of houses.  Its presence has been now been confirmed in Georgia, North Carolina and South Carolina.  Prior to being discovered in the United States, the species had been reported in Asia, the Indian Subcontinent and Australia.

The kudzu bug gets its common name because the invasive plant, kudzu, is one of its favorite foods.  Unfortunately, in its native range it is also considered a pest on important agricultural crops like soybean.  It is also known to feed on other crops such as beans, sweet potato, rice, wheat, citrus, potato and others.  Kudzu bugs are known to have several generations each year.  As temperatures and day length decrease, kudzu bugs seek shelter in protected areas including structures. Residential and commercial buildings located close to food sources (agricultural fields or kudzu stands) are at particular risk for invasion, since this species is an excellent flier.  Similar to boxelder bugs, multicolored Asian lady beetles and the brown marmorated stink bug, kudzu bugs will congregate on the vertical surfaces of buildings to warm themselves in the fall.  As temperatures cool they will move inside structures through cracks, crevices or other openings, to spend the cool winter months.

Treatment recommendations to manage kudzu bugs include exclusion by sealing potential entry points and screening vents and other openings.    Bugs will begin migrating from food sources (typically kudzu or soybeans) as temperatures cool, and may continue for several weeks.  Applications of appropriately labeled insecticides to surfaces where kudzu bugs may rest or into and around potential entry points may be useful. Wettable powder, microencapsulated or other longer residual formulations may offer the best results.

I found what I originally thought were gnats, but appear to be really tiny cicadas clinging to the inside of a window screen in a customer’s house.  Are they cicadas?  What are they doing inside the house?

The insects that you are encountering are called psyllids (SIL-ids) and are commonly called jumping plantlice.  These insects are typically not a pest indoors, but may have found their way in from the outside through cracks and crevices as the weather cools.  They can be a pest in ornamental plants particularly hackberry trees (Celtis occidentalis).  The hackberry psyllids (Pachypsylla celtidisvesicula and P. celtidismamma) create galls on the upper surface and underside of hackberry leaves.

Adult psyllids overwinter in protected sites such as in cracks and crevices under loose bark or behind the siding of structures.  After emerging from these sites in the spring, hackberry psyllids lay eggs on hackberry tree leaves.  As the nymphs grow and feed on the leaves, the plant defends itself by growing abnormal fleshy tissue that surrounds the growing psyillid, creating a gall.  Usually the presence of galls is not harmful to the health of a mature tree.  Adult psyllids emerge from feeding inside galls in the late summer and will congregate on the sunny sides of buildings, eventually finding their way inside cracks and crevices around windows.  Some psyllids are so small that they can even penetrate through screens with openings larger than size 18 mesh.

Psyllids are typically nothing more than a nuisance pest, and as the weather becomes colder, the infestation may resolve itself.  However if the problem occurs year after year, it might make sense to recommend that the customer have any hackberry trees on their property showing signs of infestation treated with an appropriately labeled product.  From an IPM perspective, psyllids are attracted to lights, so it makes also makes sense to address outdoor lighting to make the structure less attractive to these overwintering pests.

Since silverfish never develop wings and the immature stages look exactly like adults (only smaller) what kind of metamorphosis do they undergo?

The types of metamorphosis can be divided into two broad categories: simple and complete.  Insects like beetles, flies, moths, wasps and fleas (holometabolous insects) all exhibit complete metamorphosis, which is characterized by four distinct life stages: egg, larva, pupa and adult.  In insects with complete metamorphosis the adult and immature stages typically feed on very different kinds of food and live in different environments.

Simple metamorphosis is a little more complicated however, and can be divided into three sub-categories: incomplete, gradual and no metamorphosis.  Incomplete metamorphosis is found in insects like dragonflies, mayflies and stoneflies (hemimetabolous insects).  There are distinct life stages: egg, naiad and adult.  The adult and naiad stages feed on different foods with naiads living in aquatic environments and possess gills which they use to “breathe” underwater.  Gradual metamorphosis is a more familiar kind of simple metamorphosis because it is found in common pests like cockroaches, termites, bed bugs and stink bugs (paurometabolous insects).  Gradual metamorphosis includes three distinct life stages, adults, eggs and the juvenile forms – typically called nymphs.  Nymphal and adult stages usually feed on the same foods and will be encountered in the same kinds of environments.  The last kind of simple metamorphosis is actually no metamorphosis at all.  Silverfish and springtails (ametabolous insects) both fall into this category.  The immature stages typically look the same as adults, feed on the same foods and are encountered in the same places.  There is no major rearrangement or changes in body structure during development.  The only major differences between adults and immature stages are size and the ability to reproduce.  So, to make a long answer short, silverfish exhibit no apparent metamorphosis at all.