My friend Jory is having problems with a flea infestation in his new house. Here’s what he has to say:

So, I moved into a new place a week ago Sunday. The woman there before me got two kittens about 3 weeks before she moved out. And there are friggin’ fleas.

So far, I’ve tried the following:

* I bombed the place with foggers TWICE. Within 20 minutes, the fleas were jumping around in the kitchen again!

* I put flea powder on the carpets

* I had the carpets steam-cleaned

* I have put diatomaceus earth around the kitchen and other places I’ve seen the fleas.

* I’ve got a flea collar in the vacuum and have been vacuuming about 6 times each day. (Pretty much every time I need to walk into a room or leave it again.)

I’m not even sure where the hell the fleas are coming from anymore, but it seems to me they’re living in the kitchen, which doesn’t even make sense. The kitchen has a linoleum/vinyl floor. The edges curl up to the kitchen cabinets, so I’m theorizing that they’re living/laying eggs under the lino, which is protecting them from the foggers and allows them to jump out moments later and appear under the kitchen cabinets from seemingly nowhere.

What do you think? Ever heard of fleas living under lino?

Thanks for your help!

Jory

Ah, the never ending battle against blood sucking insects. Fleas have got to be some of the most annoying, because they seemingly appear out of nowhere and last for ages! Well, onto the questions.

First off, a little bit about fleas. Fleas are a wingless, blood sucking insect that feed on animals (and therefore humans). There are good number of different flea species, but the most common flea causing problems in a household is the cat flea, or Ctenocephalides felis.  The good news with this flea is that it doesn’t transmit plague (unlike the rat flea which spreads bubonic plague). Since I don’t have a specimen to identify, I’m going to assume that Jory has C. felis.  The bad news is it is still a blood sucker, and therefore still really annoying to anyone unlucky enough to get infested.

Most fleas spend their time on animals, blood feeding for several days or until they are groomed or knocked off. The cat flea doesn’t infest humans (i.e., doesn’t stay on humans for long periods) but can and will bite humans for a blood meal. Flea bites present as small, round, red marks, usually on the ankles or lower legs. People who are sensitive may see raised bumps and experience intense itching and rashes. Sever allergic reactions take approximately 12-24 hours to develop, and can last over 7 days. In the case of a bad reaction, a topical antihistamine cream, and an oral antihistamine may be used to treat the symptoms.

Fleas have a relatively simple life cycle, which makes interrupting said life cycle easy. The female flea must take a blood meal in order to produce eggs. She then lays her eggs within 2 days of her first blood meal. The eggs are found in pet bedding, carpet, upholstery–that sort of place. The eggs are tiny (1/50th of an inch), white, and generally round. They are rather delicate, and can be dried out by many products. A single female flea can lay up to 27 eggs per day for around 9 days.

The female flea also excretes what she doesn’t use of the blood meal as feces, often termed “flea dirt” which serves as food for her young. The feces looks just like dirt, and can most easily be seen in the fur of infested animals. FYI–if you were to place this dirt in water, it would rehydrate and turn the water bright red. Science is fun AND interesting!

The eggs hatch between 2 days and 2 weeks after being laid (depending on temperature–optimum temperature for this species seems to be between 80 and 90 F, with a relative humidity of 70%. They will hatch at lower and higher temperatures, just not as quickly or readily. They don’t seem to hatch below 50 F) into a small, worm-like larvae. These larvae are the most vulnerable stage. The larvae live in the carpet, bedding, or upholstery, feeding on flea feces in those same areas. The larvae go through several stages, or instars, in this form, and stay as larvae for as few as 6 days, to well beyond 2 weeks, once again depending on temperature.

Once the larvae have finished their instars, they begin to collect debris in their immediate area–things like hair, dust, dirt, fibers, etc. They use these debris and a silky material produced by their saliva to construct a hard casing around their entire body. This casing is almost impossible to see, because it is to completely camouflaged with its surroundings. The flea undergoes a complete metamorphosis inside the casing, where it breaks down its body into its basic components and reforms it into the adult flea form. This stage is very hardy–it can take a lot of stress and abuse without dying. In fact, most insects use the pupal form to survive adverse conditions, such as winter or drought. Fleas are no exception, and it is very, very hard to kill the pupal stage.

Pupae take between 7 and 10 days to emerge into adults. However, if conditions are adverse, they newly formed flea may stay in the pupal casing until it is all but guaranteed a blood meal after emergence. This is why an empty home can suddenly have a flea infestation right after you move in. Fleas can stay dormant in the pupal stage for months at a time, waiting to sense a blood meal. Vibrations caused by walking and moving appear to trigger the dormant insects into emerging all at the same time. Fun for all involved!

Newly emerged adults must have a blood meal to survive. They will attach to any animal that happens to be in the area, feed, mate, and repeat the cycle.

So, in an indoor habitat, let’s assume that the average temperature is 75 F most of the time. This would put the life cycle at 1 week for the egg stage, 10 days for the larvae, and 10 days for the pupae (approximately). That’s about 27 days for a flea to go from egg to adult. Assuming Jory moved into his home and didn’t notice any adult fleas when he went to look at the place, then all the fleas he’s dealing with now were in the earlier stages of development–egg, larvae, or pupae. So what should he do?

Provided you don’t have a pet that is re-infesting the house, fleas are rather easy to control. The simplest thing to do is vacuum. A recent study showed that vacuuming up any stage other than pupae kills the flea (so eggs, larvae, and adults are all killed by the vacuum) so the first step to control is to vacuum any and all areas that are infested. Make sure you include upholstery, beneath furniture, and along edges. Jory mentioned that he thought there may be some fleas beneath the linoleum. Remember that all an immature flea needs to survive is flea dirt, so it’s very possible for fleas to live in all kinds of habitats. Vacuum wherever fleas are suspected.

Flea bombs are a way to quickly kill adult fleas, but they present their problems. They must be used in a tightly closed area, and are designed for specific square footage. If you attempt to use a bomb incorrectly, it will not kill the adults at all. Secondly, there are really only a few pesticides licensed for indoor use. Fleas have this annoying ability to evolve, and the more they are exposed to a pesticide, the more likely they will become immune from it. Jory has tried the flea bombs, and says they fleas come jumping out right afterwards. This tells me they have been exposed before, and are now immune to whatever is in the bomb. I suggest finding another type of bomb with a different pesticide in it, or simply physically remove the fleas with a vacuum.

Diatomaceous earth is a great way to kill eggs and larvae. The fossilized diatoms act as razor blades, cutting the integument of the fleas to ribbons, and causing the fleas to dehydrate or bleed to death. This doesn’t work as well on adults, but works a bit. Spread the DE around any areas where fleas are found, wait a bit, then vacuum it up.

The biggest thing to do is wait. Remember the life cycle–you can easily kill the eggs and larvae, but the pupae are a pain. You may have to wait them out for up to 2 weeks. Vacuum at least twice a day, wash bedding, and clean upholstery, and within a month you should have interrupted the life cycle. Good luck!

Update: I’ve gotten a lot of questions about outdoor habitats, so I thought I’d add what I do whenever I move to a new place.

I have dogs and cats. These dogs and cats love going outside and bringing back whatever critters they find (the least of which is fleas!). Fleas are often found in the yard, especially in areas where an animal sleeps on a regular basis. This is a very common place to find flea larvae, in fact. As your pet sleeps outside, he will allow the adult fleas to drop flea dirt into the soil, and feed the flea larvae. If you don’t treat the outdoors as well as the indoors, you will end up reinfesting your house every time your pet walks outside.

When I move into a new place with a yard, the very first thing I do is treat the yard. Since I have pets and a garden, I HATE using chemical sprays outdoors (besides, I don’t want to kill off the fireflies and other awesome things I have back there!). So, I instead rely on flea nematodes–a microscopic worm-like organism that feeds on the flea larvae and lives in the soil. I buy mine from Amazon, and sprinkle the entire back yard, focusing on the areas where my dogs and cats sleep.

Now, keep in mind that this is a long-term treatment, and won’t completely eliminate the fleas in your yard right away. Instead, the nematodes will reproduce from year-to-year, providing long-term control. Bonus: these nematodes also feed on other undesirable plant pests like plant-eating beetles and some flies. Excellent!

Once you have treated the entire back yard, you can keep an eye out for where your animals sleep. After my pets have settled on an area, I buy another box of nematodes and heavily treat the preferred areas. I repeat this step every two years or so (depending on the flea infestation I notice each spring and summer). I tend to have no fleas in the back yard by the end of year three, and only have to spot check every once in a while. Good luck again!

Update 2015:
For those of you who don’t know, I live in Texas. Over the past few months we’ve been having epic rain storms, and the moisture, coupled with the warm weather, has been a boon for fleas around here. We’ve also had an influx of stray cats and other warm-blooded animals trying to get out of the rain, which means our domestic animals have been fighting a flea epidemic the like of which I haven’t seen in a long time.

This epidemic prompted me to start looking for new flea treatments. You see, with my normal maintenance, we haven’t had to deal with a bad flea season in a long time. This one took me by surprise! Luckily, in the years since I’ve had to do emergency flea treatments, there have been some new developments in the flea control market.

The one that I found that has worked the absolute best is Nitenpyram, sold under the brand name CapStar, or its generic name CapGuard. The chemical binds to the neural system of insects, and causes death within a few minutes or so. It comes in pill form, which is administered to cats and dogs over a certain body weight. The chemical is ingested by ectoparasites (like fleas) through blood feeding, and the fleas die 30 minutes after the animal takes the pill.

I was a little skeptical about this treatment, but I must say it worked beautifully. One of our cats was especially heavily infested (he’s awfully friendly with the neighborhood cats), and he spent about an hour scratching and running around as the fleas began to die off. They didn’t go quietly–I could see the suckers running around his fur, and I can only imagine how much that itched! By about 2 hours post pill, however, he was completely flea free for the first time in two months.

This pill is supposed to continue to kill off fleas for about 48 hours before the chemical is completely eliminated from the animal’s system, so it needs to be used in conjunction with a repellent (like Advantage or Frontline) to ensure the fleas don’t reinfest. It’s a great way to remove the fleas from animals, though, so you can get that population knocked down!