Winter has its own pest problems

Paper wasps are common throughout Texas, frequently nesting
in windows and under house eaves. With the advent of cold
weather, many of these wasps will head indoors.

Years ago, a friend described a memorable pest control experience that still makes me chuckle. It was winter, and she had noticed a few wasps flying around her immaculate home. So naturally she called her pest control company. Her technician arrived and noticed a wasp on the fireplace. When he opened the chimney flue to investigate, to his (and her) horror a large ball of paper wasps fell from the flue into his lap. He turned to my friend, fear in his eyes, and yelled, “LADY, GRAB YOUR BABY AND GET OUT OF THE HOUSE!”

I don’t recall how long it took them both to recover their wits and clear out the wasps; but if the PMP had known a little more about paper wasp biology and behavior he could have displayed more finesse and saved his customer an unnecessary fright.

Paper wasps are one of many insects that enter homes and other buildings during the fall and winter. Like paper wasps, many insects protect themselves from cold by instinctively seeking shelter in trees, natural rock formations and (in towns) buildings. This leads to a number of insects that are seen indoors only during the winter months. It’s important to realize what’s going on and how to recognize these often-interesting invaders when they show up in your account.

Polistes wasps 

Take my friend’s wasps. Paper wasps are the most common form of wasp in most Texas towns. The come in different colors and go by different names (e.g., red wasps, hornets, umbrella wasps); but all belong to the same wasp genus, Polistes. During summer months they can be recognized by their umbrella-like, paper nests that hang under eaves of houses, in sheds, and in trees. Polistes wasps do not enclose their nests with a paper envelope like hornets or yellowjackets; but they will sting anyone who gets too close or disturbs their nest. Every fall they exchange their paper nests for locations where they will be protected from ice and winter storms. Preferred sites are high points like chimneys, multifloored office buildings and towers.

Box elder bugs may enter homes in late
summer by the hundreds. 

Unlike summer-active wasps, overwintering paper wasps show little or no aggression. Without a nest to defend, wasps simply lack the instinct to sting. A fly swatter or vacuum are all that is needed to dispatch wasps safely. If my friend’s PMP had calmly put down his lapful of wasps and asked for the vacuum cleaner, no babies need have been evacuated.

Box Elder and Red-Shouldered Bugs 

Box elder and red-shouldered bugs (Boisea trivittata and Jadera haematoloma) are true bugs that feed on seeds of certain trees. They often become pests in later summer and fall when they seek protection from cold weather. To them, buildings must resemble big hollow trees, similar to what they would use for shelter in the woods. Control these insects by sealing doors and making sure window screens are tight and in good repair. Neither insect is damaging to the trees they feed on and they are mainly nuisances when they come indoors. During the summer box elder bugs will be found on box elder and maple trees. Red-shouldered bugs are feeders on soapberry, Chinaberry, golden raintree and other trees in the soapberry family.

Nipplegall Makers 

The hackberry nipplegall maker (Pachypsylla
celtidismamma) is common in homes, especially
where there is a nearby hackberry tree. 

Hackberry nipplegall makers are common wherever hackberry trees grow throughout Texas. These tiny (2 mm-long) insects are small enough to get through most window screens and any small openings in buildings. In the summer these insects form nipple-shaped galls on the leaves of hackberry and sugarberry trees. When they emerge by the thousands from their leafy homes in late summer they are commonly found indoors and especially around windowsills. The good news is that hackberry nipple-gall insects are pretty harmless. They do not bite, do not eat clothes and are a pest only because we don’t like little bugs in our homes.

Multicolored Asian Lady Beetles 

The multicolored Asian lady beetle
(Harmonia axyridis) has become a common
fall indoor pest in Texas homes.

One of the most annoying of the fall invader insects are multicolored Asian lady beetles. These large lady beetles are natives to China and have been causing homeowners headaches since the early 1990s when they first appeared in Texas. In their native Asian home, these lady beetles move into crevices in limestone bluffs in the fall. In the U.S. they are more likely to move into light-colored homes and buildings in wooded areas where the beetles feast on aphids during the summer. Caulking and sealing along roof lines and vacuuming up the (sometimes large) aggregations of beetles where they cluster indoors or in attics is the best solution.

Cricket Hunter Wasps 

The Texas cricket hunter wasp may be
one of the least well-known household
pests in Texas. 

Maybe the least widely recognized fall invader is what I call the Texas cricket hunter wasp. These medium-sized (1/2 inch), black wasps with dark wings can be found year-round but are most common indoors during warm days in the winter and spring. They are commonly seen actively climbing up and down walls of bathrooms and other living areas. So, what are these wasps doing in homes? In nature, female cricket-hunter wasps establish nest sites in holes in the ground, such as rodent burrows, and provision those holes with fresh crickets for their offspring. In urban areas the wasps substitute weep holes and cracks in soil under building foundations for nest sites. Hundreds or possibly thousands of crickets may be stashed under homes or in walls. During periods of warm weather, the wasps’ offspring that have fed on these dead crickets can emerge indoors in large numbers. For more information on these wasps, and how to deal with infestations, check out my online factsheet.

Wintertime may be slower for the pest control business in Texas, but there are still plenty of pests out there. It’s a sign of a true pest control professional to be familiar with the less commonly encountered pests--don’t be caught off-guard when that next winter pest challenge drops in your lap.

Wind turbine woes

Wind turbine near Abilene, TX.  NY Times photo.

When does urban entomology have nothing to do with houses or cities?  Perhaps no better example can be found than the recent email received by my colleague  Dr. Chris Sansone.  He was contacted concerning a wasp problem by the supervisor for a company that provides maintenance services for wind turbines.

If you haven't traveled recently to west Texas, or the corn fields of Iowa or Minnesota you may have missed the sprouting of thousands of towering wind turbines on the vast, windy plains of America.  The size and scope of these wind farms is truly amazing, providing a reported 4.5% of Texas' energy.

Apparently 2010 has been a banner year in many areas for paper wasps. Paper wasps, genus Polistes, are the most common of the social wasps around the state, with nests easily found around most homes and buildings.  Polistes wasps are predators on caterpillars and other insects, and build umbrella-shaped paper nests under tree branches, under eaves of buildings and in windows.

Paper wasps around the entrance to a wind turbine. 
Photo courtesy Aaron Foster.

Most Texans learn sooner or later to respect paper wasps for their powerful sting and their willingness to defend their nests with joint attacks on intruders.  No wonder then that maintenance crews of wind turbines get a little skittish when wasps gather at turbine doors at the ground, inside the tower and, even worse, at 300 feet around the generator housing (nacelle).  Imagine being at the top of one of those towers and getting a face full of wasps!

This phenomenon should not surprise pest management professionals who have observed paper wasp behavior over the years.  Each fall, we see paper wasps abandon their barren nests to seek shelter for the winter.  These overwintering wasps are queens, and they are especially drawn toward structures, especially tall structures in their search for overwintering quarters.  Tall buildings, chimneys and towers are common points of congregation for paper wasps during the months of October and November in Texas.

This behavior explains the high frequency of complaints by office workers (and homeowners) of wasps in buildings during late fall, winter and the early spring months.  Once inside the attic, or false ceilings, of buildings, paper wasps will move around, especially during periods of warmer weather.  These same wasps frequently find their way into living and working quarters, to the dismay of people.  The good news, however, is that without a nest to defend, these wasps have little fight in them.  Therefore, there is little risk of being stung by wasps at this time.

Wind turbine crews aren't the only high fliers worrying about wasps.  Communications tower workers, construction workers and even NASA launch pad workers have discovered the fondness of paper wasps for high places.  When encountering wasps in such locations I have no doubt that the best course of action is to keep calm, wear clothing that can be buttoned tight and try your best to ignore the critters.  Of course you're not getting me up there to test the theory.