Don’t mess with Dobsonflies



The sweet, pungent aroma of valerian wafts into my car windows as I drive about on and off island these days. This tall flower grows in many fields and along the road. Its perfume is heady; a little bit goes a long way, and it is easily remembered. This is a non-native invasive plant that has spread widely throughout this area. Take time to experience the heavy fragrance.

Dobsonflies have been a serious topic of conversation this past week, and the topic sent me to reference books and the internet for more information. The adult Eastern Dobsonfly is a very strange and a bit of a ferocious-looking creature, and you should use caution when handling one. The male is harmless, but the female can give you a painful bite. When the Dobsonfly is in the larval form, it is called a “hellgrammite” and is well known to fisherman, for it is used as bait.

After the Dobsonflies mate, the female lays her eggs in a coin-sized mass with a strange looking white substance all over it. She places this on a rock or branch near a stream. Some observers have noted that the eggs look like bird droppings. After the eggs hatch, they fall into the stream or crawl to the water. For about two or three years, the hellgrammites live underwater trying to avoid being eaten by numerous other creatures as they hide under rocks. They are not very good swimmers and hold on to sticks and rocks with little hooks on their abdomen so they don’t get washed away.

As adults, Dobsonflies live only a few days. Males live about three days and females live from 8-10 days. They are abundant in Maine. You may encounter them when they are attracted to lights at night. You most likely will see them on windows, screens or near outdoor lights at night. Many are collected by fishermen to use as bait for catching largemouth bass, catfish and other fishes. Hellgrammites are a help in controlling aquatic insect pests. The nymphs of Dobsonflies are terrors of small insects

The adult Dobsonfly is a big insect with large wings, but despite the large wings, adults are weak and fluttery fliers. Their color varies from yellow to dark shades of brown. The Dobsonfly may be attracted to mercaptan, an indicator additive in natural gas and propane, and may behave as an animal sentinel in the presence of these gases. Adults are nocturnal. If you have access to a computer, I suggest you look up the photos of Dobsonflies so you’ll recognize them. When Dobsonflies are at rest, the wings are folded along the length of the body, and the wings are densely lined with intersecting veins.

If you decide to pick one up, make sure you recognize the male from the female, for she bites. When I visited an insectarium in Newfoundland in June, I was given the opportunity to hold a very large walking stick from the tropics on my hand. It covered my hand. After a few moments, I felt a pinching sensation that kept getting stronger, and I discovered I was holding a male and not a female. In this insect family, it is the male you should not pick up. It wasn’t terribly painful, but I happily gave it back to the curator and would not pick one up in the jungle on my own.

When I told my young 7-year-old grandson about my encounter, he told me about a big tarantula he had held in school when The Bug Man came to visit in the spring. I happened to see that presentation and thought it was an excellent opportunity for children of all ages. Generally, most of us are quite uninformed about the insect and spider world.

I happened to sit down on the fence near where purple vetch was growing one day, and out of the corner of my eye, I noticed some bumblebee activity. Sometimes four and even five bumblebees worked vigorously on the colorful blossoms. They reached into the small blooms and went about their business with great determination. They had no interest in me, and I actually was eye to eye with them. Bees have a very structured life. They all are born for a special purpose and life’s work in order to keep a healthy hive. They need each other to survive. It made me think of that wonderful song some of you may remember called “No Man is an Island.” As I watched the bumble bees, I noticed there were two different kinds working on these plants.

Tansy blooms are readily visible now; their bright yellow flowering heads are beautiful in the sunshine and commonly found all over the island. This flower came to America as a cultivated herb. The colonists didn’t want to be without their tansy bitters and especially their tansy tea. Seen under a hand lens, the leaves are dotted with glands containing oil that gives the plant its strongly aromatic flavor and scent. It is this oil that has given the tansy its value in medicine and cookery. In medieval times, tansy was strewn on the floors to give a fresh scent to poorly ventilated rooms. As well as having a strong, pleasant, spicy scent, tansy repels fleas and lice and generally acts as an insecticide. This insecticidal property helps to protect tansy from leaf-chewing insects.

Tansy soon escaped from colonists’ gardens and is now found along waysides from Maine to South Carolina and west to South Dakota. Its yellow, flat-clustered flower heads have been described as looking like a daisy without the white petals. The single flower head is really a collection of many flowers; the leaves are fern like.

Send any questions or observations to [email protected] or call 244-3742.

 

Ruth Grierson

Ruth Grierson

Columnist
Send any questions or observations to [email protected] or call 244-3742.

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