Saturday, November 15, 2008
I saw a package of "Pre-baited Hobo Spider Traps" at Home Depot the other day. Hobo spider is a species here in the northwestern US that many people are concerned about. So what are these "baited" traps all about?
First a little background. Only a few spiders ever wander very far from their webs. Most construct complicated silken webs that they use to capture prey. Because of this sedentary existence relatively few species end up indoors. Some spiders, however, spend all or part of their lives away from any sort of permanent web and wander in search of prey or mates, and thus sometimes do enter homes.
Two spiders that move readily from place to place are the brown recluse spider and male hobo spiders (drawing above). Brown recluse spiders build a simple web generally hidden away from activity. They spend daylight hours in the web but wander away at night in search of food. Hobo spiders make a more permanent funnel web where they spend most of the year. In the fall, however, male hobo spiders leave their webs and go in search of female mates. Because they are so active both spiders are commonly found in houses as well.
Bites from both of these spiders have been blamed for serious necrotic wounds. The case for venom in the bite of brown recluse spider is pretty well established, however the data are less clear in the case of hobo spiders. (See the hobo spider link above for information about what might be causing reported wounds.) Nonetheless, neither spider is a welcomed guest in most homes!
Use traps not insecticides!
In parts of the US where these spiders occur (see the links above for their distributions) the best approach to control wandering spiders is to use sticky board traps, not insecticides. Insecticides can be messy and dangerous when used indoors, and they don't work very well for these spiders. A better approach is to place sticky traps in rooms so that a wandering spider might wander in and get trapped. The traps use no insecticides. See the link below for ways to construct your own traps and how they should be placed.
So what are the "pre-baited" sticky traps baited with? I don't know. Spiders are mostly predators and respond to live prey but obviously the traps are not baited with anything alive. There is some evidence that brown recluse spider is a scavenger when live prey are scarce but these traps apparently specifically target hobo spider. My guess is that the term "pre-baited" is only marketing hype. The traps are likely just simple sticky traps similar to those you could make yourself. Bottom line: whether you make them yourself or buy them from a commercial source sticky spider traps are better than insecticides for spiders that enter homes.
Monday, September 08, 2008
Just in time for the start of school we have a new head lice treatment. LiceMD (tm) is a liquid gel of a silicone lubricant called dimethicone. Like similar products, LiceMD (tm) detangles and lubricates hair making nit combing with fine-tooth lice combs easier and more effective. Nit (louse egg) removal is the single most important part of any lice control procedure (see why below).
LiceMD contains no pesticides and is odor free and hypoallergenic. The manufacturer claims that LiceMD eliminates head lice in 10 minutes but I think this claim is a bit of an exaggeration because it is the comb-out that actually removes nits and even the manufacturer's website states that the comb-out will take "1-2 hours". Nonetheless, if LiceMD or another product will make nit-combing easier and more effective it is probably worth a try (see why below).
Head lice and school kids - background information
As kids return to the classroom this fall head lice will once again be an issue in many grade schools. Head lice are small, wingless insects that bite in order to feed on our blood, much like mosquitoes and bed bugs. The bites are not medically significant but do produce intense itchiness, and, let's face it, extreme revulsion at the thought of something feeding on us or especially our kids!
As an extension entomologist (now retired) at Oregon State University (see my profile and bio) I get questions from teachers and parents every year about head lice control. Interest seems to peak in the fall when kids return to school. Over the years it has become clear that the best way to eliminate a head lice infestation is to go after the nits (lice eggs). The best way to eliminate nits is, however, both tedious and time consuming. This article describes some ways to make nit removal a little quicker and easier.
Head lice start out as tiny eggs, or nits, that are attached to hairs (photo left), generally near the scalp and often on the nape of the neck and around the ears. Nits hatch in a few days and the head lice begin biting. All stages feed on blood but it may take several weeks or longer for a louse infestation to get large enough to be noticed.
See this page about head lice for additional information about lice and their control.
Head lice are very contagious and can spread from kid to kid through close contact or sharing of hats, brushes, and such. Parents and teachers know that a single infested student can spread lice throughout a classroom. Because of this potential to pass lice from child to child many schools have adopted so-called no-nit policies that are meant to exclude infested children from school until they are treated. While we do not advocate no-nit policies (here's why), it turns out that nit removal is the single most effective way to stop a head louse infestation in its tracks.
How does LiceMD, and similar products, work?
So what's the best way to eliminate nits and stop an infestation? Simple combing, with the proper type of comb, is the best way to remove and kill nits. Combing with a fine-tooth metal lice comb scrapes away or crushes nits between the teeth of the comb. Regular combs don't work. You must use a fine-toothed lice comb to be effective. Combing works better than medicated shampoos or conditioners which work well on immature and adult stages of these blood suckers but not very well on eggs.
The problem with fine-toothed metal combs is they are murder to pull through hair. Even short hair is tough to comb with these nasty torture devices and long hair is a nightmare. Most people give up and hope that the medicated shampoos and conditioners do the job. Sometimes they do work but many times shampoos and conditioners alone fail, and the failure is frequently blamed on something called "pesticide resistance". The real reason shampoos and conditioners fail (besides the fairly rare occurrence of actual pesticide resistance) is because nits hatch after the effects of the shampoos and conditioners wear off and these new lice start the infestation all over again.
So how can you make nit combing easier so both you and your child will tolerate the whole procedure? This is where nit-combing aids come in to play. Nit-combing aids are lotions or gels that make hair slippery so that the fine-tooth nit comb glides over individual hair strands easier with less pulling, tangling, and crying.
There are two products to consider trying and both work in a similar way. LiceMD (tm) is relatively new and is applied to dry hair whereas RID Lice & Egg Comb-Out Gel (tm) is applied to damp hair after shampooing. The active ingredient in LiceMD is dimethicone, a type of silicone oil which makes hair very slippery and easier to comb. The RID product is a more conventional hair conditioner.
Either product is somewhat messy so be patient and work slowly and carefully. The silicone oil in LiceMD won't dry out while combing. Both products should be washed out of the hair when done and both should be combined with a lice shampoo or conditioner to kill active lice stages. Treating of bedding, clothing and household furnishings with insecticide, however, is not necessary.
Tuesday, March 18, 2008
In 2007, many newspapers ran articles concerning the disappearance of bees, crop pollinators and songbirds. Farmers are becoming alarmed that there will not be enough bees around to pollinate their crops. These crops are our food supply. So what is happening to the bees?
A look at our life styles gives us the answer. Our dependence on chemicals permeates every aspect of our lives. Walk through garden supply departments and see rows and rows of chemicals. When citizens douse their lawns and gardens with pesticides to try to have the greenest lawn or the prettiest flowers in the neighborhood, they use chemicals that are toxic to bees. In our pursuit of perfect produce, farmers spread pesticides, which are considered highly toxic to bees.
Many cities spread pesticides to control the aphids and leaf miners and other insect “pests”. One of the most commonly used pesticides is Imidacloprid (a neonicotinoid class of pesticide), which was outlawed in France because of its toxicity to bees. This chemical stays in the soil for months, and in some cases years. Even small amounts will disorient bees to the extent that they cannot find their way back to their hives. The bees also lose the ability to groom themselves, exposing them to mite and virus infestation and death. Imidacloprid is applied to the soil within a tree’s drip-line, where it is absorbed by the root system and then spreads to the leaves and flowers where bees forage. Imidacloprid is not just absorbed by the target trees, but by any flower or plant growing in the soil where it is applied. Even clover, which grows under the trees becomes deadly to the bees which forage there. Imidacloprid is also toxic to earthworms, which live in the soil and to fish if it enters the storm water that drains into our lakes, streams, and rivers.
Our songbirds are also affected by pesticide use. Research has shown that birds which eat insects which have eaten pesticides become sick and in many cases, die. At one time DDT was thought to be safe, until many years elapsed and we discovered how detrimental it was to the environment and the creatures living in it. Could imidacloprid be the next case of DDT? Each of us can help curb a natural catastrophe (and a potential risk to human health) by not applying pesticides to our own yards or farms and also by calling your city to ask them to stop using chemicals, which are threatening our birds and bees. There are more environmentally safe ways to deal with harmful insects.
Remember, pesticides cannot distinguish “good” bugs from “bad” bugs.
Possible culprit identified in decline of honey bees
Earth & Sky Radio Series about Colony Collapse Disorder
Environmentally friendly pest control
Saturday, March 08, 2008
The truth is most are harmless or even beneficial and the few that do have a venomous bite may not be as dangerous as we once believed.
In the US there are three spiders that get blamed for most of the so called "spider bites" that end up in emergency rooms. Where you live largely determines which species gets the blame. The three common culprits are: brown recluse, black widow, and hobo or aggressive house spider.
Brown recluse spiders are only found in the south central US. Researchers have tried to find specimens of the spider outside this range but have repeatedly failed. Despite the lack of actual spiders, even the medical community continues to report bites and ulcerating ("flesh eating") wounds attributable to brown recluse -- what's going on here?
Turns out there's a skin bacteria called methicillin-resistant Staphylococcus aureus, or MRSA that causes open, ulcerating wounds that researchers now believe accounts for many of the wounds that were once attributed to brown recluse spider. Wounds are very red, tender and very slow to heal.
Bites from the other "flesh-eating" spider, the hobo spider, which is found mainly in the Pacific Northwest, and often misdiagnosed as brown recluse, results in similar wounds. The MRSA bacteria may well be involved with reported injuries from this spider, too. Hobo spiders are not even considered to be venomous in their native range in Europe.
To confirm a MRSA infection requires a laboratory culture and several days. Most physicians won't bother because in the end the treatment (spider bite vs. bacterial infection) is the same.
On the other hand, black widow spiders, which occur throughout the US, have a venom that acts on the central nervous system and can be very dangerous, even life-threatening. Black widow bites do not result in ulcerating wounds but rather affect muscles and nerves. Pain, tremors and breathing difficulty often set in within minutes of a black widow spider bite.
If you believe you have been bitten by a spider try to collect the specimen and have it identified.
The electron micrograph photo above was taken by Marc Castagna. The image shows the fangs (inwardly pointed "chelicerae" in lower part of photo) and pedipalps (upper, "boxing gloves") of a spider. In life the fangs are only about 1/32".
Thursday, March 06, 2008
Drain flies, also called moth flies (another image of drain fly) are small (~1/10") hairy flies that are commonly found in kitchens and bathrooms. Larvae of drain flies can develop in the organic, gelatinous material that builds up inside pipes and hence can be very common around sinks. They are also common outdoors near sewage plants and waste ponds. Adult drain flies are covered with scales that makes the fly look like a tiny moth. Flies may be attracted to lights and windows. Eggs are laid on the gelatinous film that forms in pipes or in sewage treatment facilities. Larvae develop in this rich organic material.
The drain flies are harmless but a close relative, the sand flies, actually transmit a serious disease called leishmaniasis. Leishmaniasis does not occur in the US.
Fly numbers can be reduced by removing the organic, gelatinous material that forms inside drain pipes. You can use a stiff brush or one of the relatively new bacterial/enzyme-type drain cleaners. Regular use of a drain cleaner will remove the layer of gunk and prevent fly development. There's no reason to use insecticides. Foaming-type chemical drain cleaners will work as well.
Don't use the bacterial/enzyme-type drain cleaners on clogged drains. For drains that are clogged you'll need a chemical drain cleaner or plumber's snake (or a plumber). The bacterial/enzyme cleaners are only intended to remove the organic film (gunk) that forms on the walls of drain pipes and such.
Friday, January 04, 2008
Pubic lice are very small insects (less than 1/10") that bite to feed on blood. Their bites results in very itchy lesions but pubic lice are not important in disease transmission.
Pubic lice eggs are laid on the hair and, like head lice, removal of these eggs, or nits, is important for effective treatment. Treatment should include nit combing and use of medicated lice shampoo or lotion.
Pubic lice infestations are highly treatable and should be no reason for panic. Since pubic lice can be transferred during sexual contact, partners of infested individuals should be treated as well.