Friday, September 23, 2005
Name: Blister beetles are in the Meloidae family which has 26 genera and over 300 species in North America. This beetle has been identified in the genus Meloe (20 species) at the web site BugGuide.net and also by an entomologist at U. Mass Amherst. The beetle fits well with the description of Meloe americanus but information on the other 19 species is hard to come by. There are about 27,000 species of beetles in North America (290,000 worldwide) so getting it down to one of 20 will have to do. All blister beetles have a defense mechanism called "reflex bleeding." When the beetle is disturbed or threatened, it exudes blood from its knee joints and from other body parts. The blood is yellow and oily and can cause nasty blisters on your skin, hence the name blister beetle. Another common name is oil beetle.
When and where found: Judy Spann of Aaron Way has been finding these beetles in her garden where they make very short work of the Jack-in-the-pulpit leaves, stripping them right down to bare leaf midribs. I saw them in action on September 13. Spann has also seen them early in July. When they appear, they turn up in large numbers.
Identifying characteristics: This Meloe beetle is a shiny blue-black. It is quite large. The biggest one eating Spann's jack-in-the-pulpits was about one and a quarter inches long. The abdomen is thick and round; the thorax is almost square; the head is much wider than the thorax; the head and thorax both have tiny puncture marks. If you pick it up, you will see drops of yellow blood at its knees.
The wing thing: Most beetles have two sets of wings. The front pair are called elytra. They are usually hard; they cover the membranous flying wings, and they don't overlap — they touch each other forming a straight line down the center of the abdomen. The Meloe beetle is different. It has no flying wings and the elytra are small and don't meet down the center back. The beetle can't fly and it is curiously clumsy on its feet.
Life cycle: Specifics of the lifecycle are hazy since I don't have the exact species. In general, Meloe beetles lay their eggs in the ground. The first larval stage crawls to a plant or flower where it is picked up by a bee and carried back to the bee's nest where the next few larval stages eat pollen stores and bee eggs. It pupates and over-winters in the bee nest.
Food: This Meloe beetle is a rather picky eater. Spann has found it on only yellow loosestrife, lady's mantle, and of course the Jack-in-the-pulpit. I took two of Spann's beetles home to try and identify them. I fed them different kinds of leaves including other types of loosestrife without success and finally discovered that the larger beetle liked cantaloupe. The smaller one has died. The big one is very lively. I find this rather promising since I eat a lot of cantaloupe myself.
Toxicity: The blistering agent in the beetle's blood is cantharidin and is highly toxic to humans. One hundred milligrams can be lethal and an individual blister beetle may contain several milligrams. Some creatures are not susceptible to the toxin. Frogs show no ill effects but some unfortunate members of the French military in Algeria were poisoned by eating frog legs from frogs that had gorged themselves on blister beetles. Horses are susceptible and can be poisoned by eating infested hay. Cantharidin also has notoriety as the active ingredient in Spanish fly, which is neither Spanish nor comes from a fly. It is ground-up blister beetles of the species Lytta vesicatoria. It was taken with equal amounts of risk and optimism in the pre-Viagra days. Its actions bring to mind the warnings on TV ads for Viagra.
References: Richard E. White, Peterson Field Guide to Beetles; European Invertebrate Conservation Trust at www.buglife.org.uk; Thomas Eisner, For Love of Insects (this is a very informative and entertaining book about some of the wonders of insect behavior); www.BugGuide.net (a web site where you can send insect photos for identification).
Please feel free to write the Biodiversity Corner. The only requirements are that the topic is something that exists in the wild and was seen in Carlisle. If you don't want to write the column, send photos, sightings, or ideas for the column to Kay Fairweather at 392 School St, Carlisle MA 01741 or to email@example.com
"There's a bat in the house"
Sure enough, the bat was flying around the inside of our sunroom, with an occasional foray into the livingroom! It was absolutely silent, and managed no to collide with anything, which was amazing considering how fast it was flying. It was probably inside the house no more than a minute or two, although it seemed alot longer than that at the time. D'Ann remembered the advice we had heard about liberating bats, and told me to open a door. Within a few seconds of doing this, the bat was gone.
A similar incident happened once before, on July 21, 1998. I discovered a bat roosting in the cellar stairwell (see photo.) This bat flew out of our house through an open door the following night. I suspect that this bat, and the one we hosted more recently, was the Little Brown Bat, also known as the Little Brown Myotis.
If you have a bat in your house, it will probably depart completely of its own volition - Just open a door or window in the evening.
© 2005 The Carlisle Mosquito