Forest ranger Frans Kapteijns shares his knowledge of nature every week. Anyone can submit questions via [email protected]. This time Frans pays attention to, among other things, a very special discovery in Moergestel, fever flies in which males have thick brown eyes, a non-dangerous and beautiful longhorn beetle, flowers that resemble traditional Indian blankets and elm dimes, also called elm snow. Part two of this Stuifmail will be published on Sunday morning.
The Stuifmail question:
Insects are invertebrates with six legs, a body consisting of a head, thorax and abdomen, and usually two pairs of wings. Why do flies belong to insects?
Please send your answer to [email protected]
The winner will receive the honor and a beautiful book entitled Brabant, poetry of landscape and society, donated by the Van Gogh National Park.
You will hear the answer on Omroep Brabant radio on Sunday between eleven in the morning and noon.
Email from Luuk Meulendijks
Dear Frans, a kind of wasp was walking around in a garden in Moergestel. After ten minutes of walking on the ground, she had enough and flew away. We had never seen this insect before and after some research we think it is the oak camel-necked wood wasp, which has only been spotted in the Netherlands since 2020, especially in Limburg and Brabant. The oak camelneck wood wasp likes oak, maple and elm wood. Because wood contains few nutrients, the larvae live in symbiosis with fungi that provide them with the necessary nutrients. The females simultaneously deposit fungal spores when laying eggs. These spores are collected during the larval stage and stored in special glands, just above the base of the ovipositor.
Are these two fever flies and are they mating in the second photo?
Margot Reijnders saw two fever flies in the silent garden near the church in her village and sent me two photos. She wonders if there is a difference between a man and a woman and whether the man has red eyes. Margot is also curious whether the fever flies in the second photo are mating.
In the first photo you indeed see two fever flies, the male having a different eye color. These are not red, but very dark brown and they are large, compound eyes that cover almost the entire head. This is clearly visible in the first photo. In addition, the males are a lot smaller than the females and have transparent, somewhat clear wings, unlike the females.
In the second photo there are indeed two fever flies mating. Such a mating begins just as with mourning flies. Large flocks of males hover over grasslands or vegetation to attract females. When a female flies up, she ends up in that swarm and a male grabs her, after which mating begins in the air. They turn their abdomens towards each other and remain firmly attached; you can see this in the second photo.
They then fly on while mating in a slow flight, but sometimes you see them resting on a leaf while mating.
The entire mating process can take several days. If mating is terminated, the female immediately dives into the bottom. There, preferably in humus-rich soil, she lays her eggs. Shortly afterwards, both adult fever flies die.
There are two butterflies stuck together, what’s going on?
Frans and Anjo Brock saw two butterflies stuck together and wondered what happened. What they saw was a mating of two agate butterflies. Agate butterflies are moths that are fairly common in our country. This species belongs to the owls, a large group of moths with more than 25,000 species worldwide.
Agate butterflies are quite large; the forewing has a length of about 2.5 centimeters. Caterpillars of this butterfly species live on herbs such as nettle and dead nettle, on shrubs such as hazel and blackberry and on trees such as the pedunculate oak and birch. After the caterpillar has eaten its fill, it hibernates as a caterpillar, but sometimes also as a pupa. That makes the species special: caterpillars can remain active even in mild winters.
So in the photo they are mating, like butterflies do: with the ends of their abdomens touching each other, while their heads point away from each other. This often creates beautiful shapes, as can be seen in the photo.
Beetle spotted, but should I be happy with this species?
Monique van den Heuvel saw an unknown beetle in her driveway next to her hedge and wondered whether she should be happy with this find. What she saw is a purple metal longhorn beetle.
People are often shocked when they hear the name longhorn beetle, but that is not necessary. Only one species can cause a nuisance in homes: the house longhorn beetle. By the way, it is not the adult animal, but the larvae that attack unprocessed wood.
The other more than eighty species of longhorn beetles in our country mainly live in dead or rotting wood in nature and do not pose a danger to homes.
As an adult, the purple metal longhorn beetle feeds on nectar, pollen and tree sap and therefore does not eat wood. They are quite rare animals that mainly occur on higher sandy soils, such as in Brabant. The adults are mainly active at dusk and at night. The larvae mainly live in dry branches and under the bark of fallen conifers such as pine, spruce and larch. Sometimes they are also found in pedunculate oaks. They feed on the wood in the fall and pupate there in the spring or early summer.
The development from egg to adult insect can take two years, sometimes even longer. They then appear in spring or early summer.
During a walk in Brabant, plants with strikingly open flowers were seen, but which species is this?
Koos Riksen was walking in beautiful Brabant (completely agree) when he saw a plant whose name he would like to know. He did not report where he had seen these plants, but the species does not actually belong in the Dutch flora.
The name of these plants is cockade flower; they are originally from North America. These plants like sunny spots on dry, slightly calcareous soil. Officially the genus is called Gaillardia, a tribute to the 18th century French botanist Antoine René Gaillard de Charentonneau.
The plant owes its Dutch name to the characteristic color gradient of the petals: which is reminiscent of a cockade, a pleated rosette of ribbons. Sometimes you also come across the name blanket flower, which refers to the striking color patterns that resemble those of traditional Native American blankets. Cockade flowers are perennials that can reach a height of about 60 centimeters. They are winter-hardy plants that can tolerate temperatures down to -15 °C.
Suddenly the sidewalk and more were littered with seeds. Are they from an elm?
At Marijke Lamers it was suddenly littered with seeds. She wondered if those were elm seeds. That’s exactly right, because elms have flat, papery fruits containing the seed. What’s nice: these fruits have popular names, such as elm dimes and elm snow.
Elm trees bloom early in the spring, usually in March, sometimes as early as late February. If you look closely, you will see inconspicuous red flowers on the tree. In April and May, the seeds develop before the leaves appear. At that moment, huge bunches of fresh green seeds hang on the tree. It then seems as if the elm is already in leaf, while in fact you mainly see seeds. Later the seeds ripen and turn light brown.
The membranous edge then takes on a function: because it dries completely, the edge works like a kind of wing. The wind then spreads the seeds en masse, creating entire carpets of seeds in some places, such as in gardens or on sidewalks. Hence the name elm snow.
The name elm dimes refers to the shape: the round, flat membranes with a seed in the middle are exactly the size and shape of the former Dutch ten cent coin, the dime. Once on the ground, things happen quickly, especially on moist soil: the seeds can germinate within a few days.
Did you know that elm seeds are edible? The young, fresh green seeds in particular are crunchy and taste slightly sweet and nutty. That is why you often see elms in food forests.
