HEAD LICE AND INSECTICIDE RESISTANCE
Recent media reports have suggested that there is the potential of the "super head louse" lurking out there--the one that is resistant to insecticides! There have been some dramatic newspaper reports of insecticide resistance in head lice in the U.S. and other parts of the world. I'll discuss the situation here, but before going further I will assure you that head lice can certainly be controlled/eliminated with current materials available for this insect. There may be some resistance in the pest population, but no super louse!
Reports of head lice on school children being resistant to insecticides began to appear in Israel and France in 1990. The resistance was linked to a pyrethroid insecticide, phenothrin. In 1994 in the United Kingdom there emerged evidence of resistance in head lice to another pyrethroid, permethrin. In some areas the head lice population is about 20-fold resistant to permethrin or phenotherin, or both. This resistance seems to have developed with 4 years of the introduction of these pyrethroid insecticides for head lice control.
There are now reports of head lice resistance in the U.S., at least to the pyrethroid insecticides. This is not surprising, considering what happened in other countries. And this is not surprising considering the ability of some insects to develop resistance to nearly any insecticide used against them. Consider the German cockroach and some pyrethroid insecticides: within four years of exclusive use some populations are capable of developing high level resistance.
There are populations of head lice that may be resistant to the insecticide used in some of the control products available to people. But the lack of control should not be immediately linked to resistance, since many people do not follow the use directions well and lack of efficacy may be linked to use and not resistance. All the head lice are not resistant to insecticides, but there may be populations in districts, regions of states or the U.S. that are resistant to some insecticides. However, there is a range of products, so there should be one that is effective.
Parents and guardians working with children that have head lice should use professional products (in south Philadelphia, where I grew up, if you had head lice you got your head shaved--done!), follow the directions, use the comb that usually comes with the shampoo treatment, and repeat when directed or necessary. Remember, there is no need to spray insecticides in any classrooms for the "control" of these insects; they don't live long off the host.
BROWN RECLUSE SPIDERS -- YIKES!
Last August a family from Louisa Co. contacted me about a spider problem in their house. They thought there was a serious infestation of brown recluse spiders in their old, three story house. I ignored their plea and assured them that what they probably had was some wolf spiders, because brown recluse spiders were just not that common here in Virginia. A few weeks ago they sent me a box full of sticky traps containing more than 20 brown recluse spiders! Well, that got my attention!
This old house had brown reculse spiders throughout, and the population seemed to be ongoing throughout the year, with young found in the warm and cold months. Vacuuming and insecticides helped, but not enough to eliminate the infestation. Infestations such as this are known from southern states, but not from Virginia--until now.
Jim Riddell in Louisa Co. has been working with the family for several months, and the spider population has begun to subside from the hundreds they have seen in the past! This served as a lesson for me to not set limits on what to expect from pests like spiders, ants, and termites.
ANTS, THE GENUS FORMICA
One of the most common ants found outside this time of year belong to the genus Formica. These are shiny black ants that look somewhat like small carpenter ants, but they nest in the soil and not in wood. The mounds of Formica are often in turfgrass or in bare-soil locations at the edge of the lawn. These are the predominant ants on flowers, especially peonies, this time of year. While they may be brought into the house with flowers, they will not infest.
Controlling the nests of this ant can be accomplished by applying liquid insecticide to the top of the mound and soaking the soil throughly. Nests may be difficult to locate, since these ants will forage a long distance from the colony.
Remember that ticks are a spring phenomenon; they are out there looking for a blood meal to grow and mate and lay eggs for next year--don't help them. Remember that household dogs and cats can pick up ticks and bring them into the house or in contact with people. Inspect these animals, especially their ears (inside and outside) for ticks. Remember that the best removal is to grab at the base of the tick and pull slowly and steadily. If bitten by a tick, be mindful for the next 72 hours for any rash or fever. Rocky Mountain spotted fever is out there, but only in about 1% of the tick population.
YELLOWJACKETS, UMBRELLA WASPS, BUMBLEBEES, CARPENTER BEES
This is the season for nest building! Overwintered queen yellowjackets are busy scouting out the best nest sites on the sides of building or in the soil, or in some shrubs. She will build a small paper nest to raise the first brood, then they will expand the nest. Control of these large paper nests begins now by locating and removing the small, starter nest. Queens will often simply move to another location to rebuild if disrubted on their first attempt to build in a location.
Those wasps that build nests without the cover--umbrella wasps--also start this time of year. The small starter nest is made by the queen that overwintered in the attic or shed, and is now establishing a nest under the eaves of the house. A short blast with an aerosol will kill or discourage her.
Carpenter bees (look like bumble bees but have a shiny abdomen) are also nest building at this time. Spraying the surface of the wood with a garden insecticide will usually discourage them from continuing. Some of the carpenter bees near a nest are males, and don't sting. The females may look threatening, but are not prone to stinging.
Bumble bees are out on the flowers and scouting for nest sites. They use a variety of cavities indoors and outdoors, so it is difficult to predict where they will nest. If you see them coming and going from a place inthe soil or an opening around the house or a shed, you can expect they are nesting there. A short blast from an aerosol insecticide may be all that is necessary to get them to move to another location.