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.

Hackberry nipplewhat?

This week has been the week of the hackberry nipplegall maker, Pachypsylla celtidismamma. I should have known when, during the Entomological Society of America's annual conference in Austin last week, I opened my 23rd floor hotel room blinds and saw the outside window covered with these insects.

Pachypsylla adults (about 1/8-inch long) are
commonly found at this time of year indoors, around windows

Sure enough upon return to my office, calls and messages were awaiting me about little "gnats"  covering window screens, outside walls, and cars. The small size of these insects allows them to enter buildings with ease, even squeezing through window screens.  Though these insects are present annually, the invasion seems to be unusually heavy and widespread this year with complaints from Austin to east Texas and the Dallas area.

Pachypsylla is a genus of tiny insects that grow up inside galls that form on hackberry leaves. Also called psyllids (SILL ids), they are not gnats or flies, but belong to the same order as the leafhoppers and cicadas. Like other gall making insects, Pachypsylla adults lay their eggs on leaves, which then start to swell around the egg or developing larva, forming a gall. After feeding on the gall tissue all summer, Pachypsylla adults emerge in the fall. Unfortunately for your customers, these adults commonly enter structures at this time in their search for a warm place to hang out and, perhaps, catch some football or prime time TV during the winter.

The nipple-like swellings on hackberry leaves give this little
insect its name.

Despite being a nuisance, hackberry nipple-gall insects are pretty harmless.  They do not bite, do not eat clothes and do not hog the remote. Apart from needing to be vacuumed up from windowsills occasionally, there is little you can do about these insects. In most cases, poor seals around windows and doors provide entry points, but truth is they can get indoors through any crack or gap in the building envelope.

Those who have tried spraying window screens with an insecticide noted that the main result is smeared windows.  If you do offer to spray, keep your sprays limited to window and door frames, and obvious gaps and cracks in outdoor siding.  I do not advise treating indoors, as these insects should die relatively quickly anyway. And no, you can't treat the trees. A vacuum is the best control tool, in my estimation.

For customers who find the invasion to be an annual occurrence, removing nearby hackberry trees and replacing them with another well-adapted tree is one possible solution.  Keep in mind, however, that these little guys can fly.  They were, after all on my 23rd floor windows  last week. So if other hackberries are nearby, cutting down the tree may not help a lot,  especially during a banner year like this.

I have no explanation for the great numbers of nipplegall makers this year.  This obscure group of insects has not been as well scrutinized as other, more important pests.  However we do know there was something they liked about 2013, rain at the right times, the temperature, or few natural enemies.