The caterpillars of the whitefield butterfly, Orgyia antiqua, with their red and yellow spots and tufts of hair on their backs, are among the most beautiful in existence. Since the hairs can irritate the skin, it is better not to pick up the caterpillars with bare hands. These caterpillars live on many trees and shrubs, such as willows, Prunus species, hawthorns, blackberries and raspberries. The female butterflies have only wing stumps and look like gray-brown bags; the males, on the other hand, have orange-brown wings with a white patch on each forewings and short feathered antennae.
Index
- Taxonomy and Prevention
- External characteristics of the whitefield butterfly
- Biology of the whiteboard butterfly
- Damage
- Natural enemies
- Therapy
Taxonomy and Prevention
Taxonomy
Orgyia antiqua (Order: Lepidoptera) used to belong to the family Lymantriidae (down butterflies), but since 2011 to the new family Erebidae (spider owls). The Erebidae are divided into three subfamilies: Arctiinae or bear butterflies (formerly the family Arctiidae), Lymantriinae or down butterflies (formerly the family Lymantriidae) and some Noctuidae (owls).
Appearance
There are twelve species of down butterflies in the Netherlands, but about 2,700 species are known worldwide. The caterpillars are hairy and can cause skin irritation in humans. The caterpillars live on woody plants and deciduous trees. The butterflies are often nocturnal, but in some species, such as Orgyia antiqua, the males also fly during the day, especially when looking for a female.
External characteristics of the whitefield butterfly
Male
The male has a wingspan of 25 to 30 mm. The forewing is 12 to 17 mm in length and has an orange-brown color with faint, slightly darker transverse bands. In the inner corner is a white, crescent-shaped spot. The male’s body is hairy. The antennae are strongly sprung.
Female
The female is light gray in color, has a swollen abdomen and only wing stumps. All her life she stays on and near the cocoon from which she came. After mating she lays the eggs on it.
Caterpillar
Female caterpillars eat about ten days longer than male caterpillars and grow considerably larger with a maximum length of 35 mm. Male caterpillars do not grow longer than about 25 mm. This is one of the few cases where sex can be established before pupation stage. Of course the female and male dolls are also different in size.
Cocoon
The full-grown caterpillars spin a loose cocoon, often between leaves or on a twig, in which they process their body hair. They pupate inside the cocoon.
Male / Source: Jean pierre Hamon, Wikimedia Commons (CC BY-SA-3.0)
Female laying egg on cocoon / Source: Grmanners, Wikimedia Commons (CC BY-3.0)
Caterpillar / Source: Andrew Dunn, Wikimedia Commons (CC BY-SA-2.0)
Biology of the whiteboard butterfly
Caterpillars emerge in May and the first butterflies emerge in June, with males hatching a little earlier than females. Males fly during the day in search of females. The female stays on or near her cocoon and ‘calls’ males by secreting a fragrance (pheromone). After mating, the female lays 200-300 eggs on top of the cocoon. She dies pretty soon after. The males also have a short life, because they do not eat.
There are two overlapping generations per year. The second generation of butterflies hatch in September. This species hibernates as an egg. The overwintering eggs have a very hard shell.
Damage
Since the caterpillars can devour large amounts of leaves, if there are many, they can cause considerable damage. However, the damage is usually limited and almost always local.
Natural enemies
The butterflies are eaten by birds, spiders and wasps of the family of the Vespidae, to which the well-known yellow-black common wasp belongs. The latter are known to ‘steal’ butterflies from spider webs.
Hairy caterpillars like that of O. antiqua are usually not eaten by birds. However, one bird specializes in hairy caterpillars: the cuckoo (Cuculus canorus).
Other enemies of caterpillars (hairy or not) are ground beetles (Order: Coleoptera; Family: Carabidae), in particular Calosoma sycophanta. The caterpillars are also attacked by parasitic wasps (Order: Hymenoptera; Family: Braconidae) and parasitic flies (Order: Diptera; Family: Tachinidae), the larvae of which develop inside the caterpillar’s body.
Therapy
Since the damage is usually limited, treatment is hardly ever necessary. If necessary, remove the cocoons and eggs in winter. Wear gloves to avoid contact with the hairs in the cocoons as they can cause skin irritation! You can also try to attract parasitic flies and wasps by growing flowers with flat, open inflorescences, such as composites (eg daisies or asters) or umbels (eg dill).
