Oct 19, 2011 – Bigger Than A Teeny Weeny Flea
QUESTION:
Several weeks ago in southern California I captured a very large flea in front of an apartment complex. It was noticably larger than a cat flea, lacking the prominent genal comb, and had rather large eyes. I have had no luck at the I.D. To make it worse I had placed it in a small collecting jar which completely dried it out in my hot vehicle that day. Any hints on what it could be would be greatly appreciated. Thanks, your knowledge of this field has been greatly motivational to me.
ANSWER:
Thank you for the compliment Shawn, and I agree that correct identification can often be extremely important, even with insects that would seem as cut and dry as fleas. The vast majority of the time the fleas we encounter in urban pest management will be Cat Fleas - Ctenocephalides felis - regardless of whether they are on dogs or cats. This just happens to be the common pet flea in North America, and also can be a common flea on wild animals such as raccoons and opossum. But, other kinds of fleas exist around homes, and if they happen to be associated with wild rodents the normal control procedures that would resolve most flea problems just might not work.
I had a friend give me a few specimens of the Mountain Beaver Flea that he collected from beaver dens during some field work he was doing, and these giants may be nearly 1/3 of an inch long, so fleas are capable of some large sizes. Of course, it's pretty unlikely that you stumbled upon some beaver fleas in front of an apartment in the Los Angeles area, so that was just for fun. Your observation that the "genal" comb was not present was a good one, and a reminder to us that identification of fleas relies on examining them under high magnification so we can observe some small characteristics. One of the most important is the presence or absence of these "combs", which are rows of spines along either the bottom of the head (genal comb) or at the back edge of the pronotum (pronotal comb). The genal combs look like a long row of teeth sticking down, and this one is present on the common cat flea, as well as on the dog flea, mouse flea, and rabbit flea.
The genal comb is absent on most of the other rodent fleas (Oriental rat, squirrel, northern rat, ground squirrel, as well as on the rare "Human" flea. You don't mention whether or not the rear comb, the pronotal comb, was present or absent, and this does separate these rodent fleas. From the basic pictorial key I have available the fleas with the largest eyes in relation to their head are still the cat flea and dog flea. Even dried out the exoskeleton of the fleas tends to stay firm enough that you can still observe the important characters for ID. What tends to dry out and shrink is the abdomen, and that is less important. Sometimes a fully grown or fully engorged female Cat flea can look "huge" in comparison with others, but since that genal comb was missing it could not be a Cat flea.
A 1943 publication called "The Fleas of California" listed 200 different species and subspecies of "western" fleas, so there are plenty of other kinds around that we could come across. Even at that time 127 of the species were confirmed from California from such diverse host mammals as gophers, bats, foxes, rabbits, moles, shrews, and of course a great many different kinds of rodents. Unfortunately this short publication did not go into details on the identification of different kinds, so we cannot provide you with the definite ID. It might be of interest for you to take this to your county department of agriculture for identification. You never know when something new and important may show up for the first time, as the recent discovery of the Asian Tiger Mosquito in southern California proves to us. And, your eyes in the field are a huge help to the state agencies in discovering these kinds of pests.
View past Ask Mr. Pest Control questions.
Several weeks ago in southern California I captured a very large flea in front of an apartment complex. It was noticably larger than a cat flea, lacking the prominent genal comb, and had rather large eyes. I have had no luck at the I.D. To make it worse I had placed it in a small collecting jar which completely dried it out in my hot vehicle that day. Any hints on what it could be would be greatly appreciated. Thanks, your knowledge of this field has been greatly motivational to me.
ANSWER:
Thank you for the compliment Shawn, and I agree that correct identification can often be extremely important, even with insects that would seem as cut and dry as fleas. The vast majority of the time the fleas we encounter in urban pest management will be Cat Fleas - Ctenocephalides felis - regardless of whether they are on dogs or cats. This just happens to be the common pet flea in North America, and also can be a common flea on wild animals such as raccoons and opossum. But, other kinds of fleas exist around homes, and if they happen to be associated with wild rodents the normal control procedures that would resolve most flea problems just might not work.
I had a friend give me a few specimens of the Mountain Beaver Flea that he collected from beaver dens during some field work he was doing, and these giants may be nearly 1/3 of an inch long, so fleas are capable of some large sizes. Of course, it's pretty unlikely that you stumbled upon some beaver fleas in front of an apartment in the Los Angeles area, so that was just for fun. Your observation that the "genal" comb was not present was a good one, and a reminder to us that identification of fleas relies on examining them under high magnification so we can observe some small characteristics. One of the most important is the presence or absence of these "combs", which are rows of spines along either the bottom of the head (genal comb) or at the back edge of the pronotum (pronotal comb). The genal combs look like a long row of teeth sticking down, and this one is present on the common cat flea, as well as on the dog flea, mouse flea, and rabbit flea.
The genal comb is absent on most of the other rodent fleas (Oriental rat, squirrel, northern rat, ground squirrel, as well as on the rare "Human" flea. You don't mention whether or not the rear comb, the pronotal comb, was present or absent, and this does separate these rodent fleas. From the basic pictorial key I have available the fleas with the largest eyes in relation to their head are still the cat flea and dog flea. Even dried out the exoskeleton of the fleas tends to stay firm enough that you can still observe the important characters for ID. What tends to dry out and shrink is the abdomen, and that is less important. Sometimes a fully grown or fully engorged female Cat flea can look "huge" in comparison with others, but since that genal comb was missing it could not be a Cat flea.
A 1943 publication called "The Fleas of California" listed 200 different species and subspecies of "western" fleas, so there are plenty of other kinds around that we could come across. Even at that time 127 of the species were confirmed from California from such diverse host mammals as gophers, bats, foxes, rabbits, moles, shrews, and of course a great many different kinds of rodents. Unfortunately this short publication did not go into details on the identification of different kinds, so we cannot provide you with the definite ID. It might be of interest for you to take this to your county department of agriculture for identification. You never know when something new and important may show up for the first time, as the recent discovery of the Asian Tiger Mosquito in southern California proves to us. And, your eyes in the field are a huge help to the state agencies in discovering these kinds of pests.
View past Ask Mr. Pest Control questions.
