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Beetles and Grubs and Ticks, Oh My!

May 2nd, 2012

Spring is well underway, and here are some of the things getting some attention as of late:

  • Predaceous Diving Beetles: These beetles, in a family of water beetles called Dytiscidae–based on the Greek dytikos, meaning “able to dive” [in water]–are out and about now, and being noticed by some homeowners. They are nothing to be concerned about, however, and you can find them in the ‘Curiosities’ group of our Fact Sheets section, as they are indeed a source of curiosity for many people.  They show up sometimes in swimming pools, or in driveways or parking lots where it is suspected that they mistake the shiny surface of many automobiles for bodies of water, as is their natural habitat (i.e. they are aquatic, and have structural modifications ideal for swimming). When in water, they move their hind legs together like oars. Backswimmers also swim this way, but other aquatic beetles move their two back legs one at a time when swimming.  As their name implies, these beetles prey on other insects and critters–such as tadpoles–small enough for them to overpower with their short, but sharp, mandibles. The larvae (which stay in the water) are also predaceous, and are commonly known as water tigers (photo of larval stage).

a Predaceous Diving Beetle a Predaceous Diving Beetle a Predaceous Diving Beetle

Above: Some Predaceous Diving Beetles found in Maine.  Most Predaceous Diving Beetles are dark brown, blackish or dark olive in color. Some have golden highlights such as the one shown above (far-right).

  • White Grubs: We are getting a lot of white grubs brought in to our office for identification, the vast majority of which thus far this season are the European Chafer [MSU provides an excellent fact sheet on this critter and we are linking to theirs until we can add the finishing touches to one of our own].  Our insect diagnostician says he is seeing evidence of their feeding damage to grass in peoples’ lawns, cemeteries, etc. in the Orono & Old Town, and Bangor & Brewer areas now.  It seems that the European Chafer has had several profitable seasons in a row, and it may take an especially harsh (i.e. COLD) winter before we begin to see their numbers decline.  As it stands now, this pest seems to be on the rise, unfortunately.

May is Lyme Disease Awareness Month in Maine!! Know Ticks, No Lyme

[Text courtesy of the Maine CDC]: Lyme disease is the most common vector-borne disease in Maine.  May is Lyme Disease Awareness Month in Maine, so remember to do your tick checks!  With the mild winter, it is never too early to start thinking about tick prevention.

a deer tick (non-engorged) next to a US penny for scale purposes

Unengorged Deer Tick (also called Black-legged Tick) (UMaine Extension photo)

Lyme disease is a bacterial infection that is carried by Ixodes scapularis (the deer tick).  Maine had a record high number of cases in 2011, with positives occurring in all 16 counties.  Lyme disease is most common among school-aged children and middle-aged adults.  As the weather begins to get warmer, more ticks will be out in the open.  Most Lyme disease infections in Maine occur during the summer months.

Note from UMaine Extension: Visit the Ticks page of our Home & Garden IPM website for more tick photos (including pictures of other kinds of ticks):

The most common early symptom of Lyme disease is an expanding red rash that occurs 3 – 30 days after being bitten.  Fever, joint, and muscle pains may also occur.  Lyme disease is treatable, and the majority of patients recover after receiving appropriate therapy.

Lyme disease is a preventable illness.  Maine CDC recommends following the “No Ticks 4 ME” approach which includes:

1.    Wear protective clothing
2.    Use an EPA registered repellent:
3.    Perform daily tick checks
4.    Use caution in tick habitats

Ticks must be attached for at least 24 hours for the bacteria that causes Lyme disease to be transmitted, so prompt removal of ticks is extremely important.  Anyone with a known tick bite, or who spends time in a tick habitat, should watch for symptoms for at least 30 days after exposure.  If symptoms develop, call your healthcare provider.

Additional information:
Maine CDC has numerous educational materials available online at


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