"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

March 7, 2010

March 7- Dipylidium caninum

Yesterday, you met the cat flea. Believe it or not, these tiny blood-feeding insects are the intermediate hosts to a tapeworm that as adults can grow up to 18 inches (or 40-50 cm) long once they are ensconced in the intestine of their mammalian host! The eggs of the tapeworm are expelled in the host’s feces and are ingested by fleas. Inside the flea, the eggs hatch and the larval tapeworms travel into the body cavity and wait there for a mammal to eat the flea – usually when they are grooming an itchy spot. Children can become infected with D. caninum if they accidentally (or purposefully?) ingest infected fleas.


  1. BTW, this blog is awesome. Gross, but awesome. Thanks!

  2. It's unusual in that the proglottids are mobile, and crawl away from the feces (which, for cats, are often shallowly buried) before dying and releasing eggs. The proglottids sometimes migrate through the anus as well - I've found them crawling in the hair like moving rice...