Fleas

It's flea season. In general, flea populations in Michigan reach their peak in mid summer. The reason is most warm and humid conditions favor population buildup. Right now, weather conditions are ideal for development of fleas, both indoors and out-of-doors.

 The two most common flea species identified at the M.S.U. Plant and Pest Diagnostic Lab by Howard Russell are cat and dog fleas; cat flea being the most common of the two. Both can be found on dogs or cats. The dog flea seems to have a preference for wild, rather than domestic hosts.

 Both species are long-lived and very prolific. In households with pet dogs and cats, flea populations are highest on the host and where the pets bed or nap.

 Damage

Cat and dog fleas are parasites meaning they derive all or part of their nourishment from their hosts. These fleas bite cats, dogs, other mammals (including humans) to obtain blood for nourishment. The most common skin reaction to a flea bites is a small, hard, red welt that itches. Sometimes, there is slight bleeding. A pet that is heavily infested may scratch itself excessively leading to other secondary skin problems. Cat and dog fleas are an intermediate host for the dog tapeworm, a common internal gut parasite of both dogs and cats. As the term intermediate implies, the tapeworm must complete part of it's development in the flea gut before it can infect the cat or dog.

 Ecology and Life Cycle

 It is the rare cat or dog that will not have a flea problem during its lifetime. It is important to understand the ecology and life cycle of fleas in order to better manage this pest in your household

 The adult flea female lays eggs primarily on the mammal host. Occasionally, the flea will fall off the host and deposit eggs in or near the pets bedding area or outside on the ground. The female will lay a few eggs each day until 200-400 are deposited. The adult fleas will die after about three weeks.

 Most eggs will hatch in one to two weeks depending upon the temperature. The actual time range for hatching is from two days to several weeks. The flea larva is a minute, slightly hairy-looking maggot. It does not feed on the host. They consume organic debris such as feces from adult fleas, skin scale, dust, etc. The mature flea larva may reach an 1/8" in length. The larva turns into a pupa after two molts (i.e., three instars). Normally, this takes about a week. Again, this is temperature dependent and the actual time range is from a couple of days of hot, humid weather to a couple of months during cool or cold weather. Flea larva are rarely seen: They often get entwined in carpet nap, bedding, mattress creases, etc.

 The flea completes its transformation to the adult form fairly quickly inside the pupal case (a couple of weeks usually). However, it may delay emergence for several months, especially during cooler weather or their are no mammal hosts present. This is a pretty clever survival strategy these insects have evolved over the millennia. Their emergence is triggered by a combination of warm and humid conditions, the presence of carbon dioxide and vibrations. Put another way, they wait for you to come in the house, turn up the heat and walk around. It is very common for our Florida Snow Birds to call us complaining that as soon as they returned from their southern retreat they were bitten around the ankles by fleas!

 Identification

 Adult cat and dog fleas are small (1/12" long), dark-colored, and wingless. They are insects so they have three pairs of legs. Viewed from the back or front they appear flattened side-to-side. Separation of the two species requires the use of an insect key.

 Flea eggs are very small and hard to find.

 The larva is a minute, slightly hairy-looking maggot not more than an 1/8" long. They are also very hard to see.

 The pupa are difficult to observe. They appear as a folded up version of the adult.

Integrated Flea Control

 As I have already mentioned, if you are going to keep cats or dogs for pets you are probably going to go a round or two with fleas before "Muffy" or "Moose" go to their great reward. However, fleas are very manageable if you keep with an integrated program during the course of the year.

 Regularly inspect your animals for adult fleas. Pick them off and dispose of them. If you see adult fleas or your pet is giving you that distressed stare and scratching excessively, it is time to act.

 This is one of the few indoor insect pests that cannot be controlled effectively with the Hoover. The larvae get a pretty good death grip on carpet and other fibers and are able to hang on when you are vacuuming. Adult Flea Control

 Adult fleas are best controlled by dusting dogs and their bedding with 5% carbaryl. Carbaryl is registered for dogs and cats. However, cats groom themselves more than dogs and smaller animals may have a problem with carbaryl. We suggest that you do not use carbaryl for cats or puppies. Instead, they should be treated with flea powders for cats. Most will contain pyrethrin or pyrethroid.

 If you do not have small children, a ready to use formulation of chlorpyrifos can be used to treat carpeting, upholstered furniture and mattresses. Apply as a light mist. Caution: certain fabrics and dyes can be affected (staining or running) by certain formulations of insecticides, so test a small, hidden area with the product before applying it. The insecticide should be applied as a fine mist to carpets. If the furniture cannot be removed until the spray dries, place a small piece of foil between furniture legs and the carpet to prevent staining.

 Flea collars can be incorporated into your control program. I would definitely advise them for pets kept out-of-doors. If you use them on indoor-kept pets do not expect them to control the fleas in the household. They will be useful. Use your own judgment with regards to putting an insecticide impregnated ring around your pets neck--especially smaller dogs and cats.

 These treatments will knock the edge off your flea problem. You still have to manage for the long term. There will be eggs and larvae present that you didn't kill.

 Larva Control

 Larval control is the key to successful flea management. Spraying and dusting will kill most of the larvae present. However, eggs are still present and will hatch soon. Also, in time, new adult fleas will be introduced into the household. For long term control we suggest using a ready to use formulation of methoprene (often times called Procur on the label). This compound is a growth-regulating hormone that prohibits the larva from turning into a pupa. Basically, the poor thing grows itself to death. This product is long lasting (only three or four applications needed per year) and apparently quite safe. The only down side is that it takes a few weeks to show results. However, incorporated into a total management program the results can be quite impressive. Use the same application techniques and take the same precautions mentioned above.

 Habitat Management

 Don't think for a minute that chemical management of fleas is sufficient. Frequently launder pet bedding and rugs that pets frequent with hot, soapy water. Vacuum thoroughly to remove lint and dust around baseboards and cracks where flea eggs and larvae accumulate. TIP: Add a teaspoon of carbaryl (powdered formulation) every time you change vacuum bags during flea season. This will kill the larvae and adults that you may pick up and, more importantly, will kill larvae that will hatch out from the eggs you have vacuumed. Install the new bag, deposit a teaspoon of carbaryl on a piece of cardboard, and vacuum it up into the new bag. Dispose of the cardboard afterward.

 Eliminate vegetation that will hold native mammals outside. Prevent pets from resting under the house, and exclude wild mammals by screening attics and eaves entrances. Thoroughly clean furniture in areas that pets tend to frequent on a regular basis, especially during peak flea months.

Important: Great care should be taken not to allow children and pets onto the treated area before an insecticide has dried. Be sure to read the insecticide label before using any pesticide and follow all safety precautions stated on the label.

This is not an M.S.U. Extension Bulletin. 
It is an excerpt from a Landscape Crop Advisory Team Newsletter.
by Tom Ellis
Department of Entomology Michigan State University