Acroceridae

Ball fly during mating

The ball flies ( Acroceridae ), also known as spiders flies, are a family of two-winged flies (Diptera ) and belong to the flies ( Brachycera ). Worldwide, about 520 species of this group of animals, of which only eight species from Germany known. These are medium-sized flies.

Features

The ball flies are very stocky and almost spherical in shape. Striking are large scales on the sides of the chest ( Thorakalschüppchen ) that cover the halteres to ( halteres ) converted hind wing. The body is often finely hairy - furry. Ball flies often have a rather long proboscis, which rests in peace under the belly, and is pre-stretched during feeding. This often happens when nectar eyes in almost noiseless Rüttelflug before flowering.

Behavior and lifestyles

The ball flies are pollinators, in a number of very kurzrüsseligen species such as Acrocera sanguinea probably occurs no food intake. Eggs are laid singly or in small scrims, often on exposed areas such as the tips of branches. Here, a single female produce about 1000 eggs, in some cases even to 5000.

Larval development

The larvae are parasitoids of spiders. The slip larvae are tiny and have the back end of a bonding apparatus. You can spanner caterpillar similar move and reach their hosts as active (spinning or spinning Tight gear). Once there, they jump at an approaching spider and penetrate through a joint skin into the body. After the first molt, the larvae are squat and stand with the rear spiracles with the lung compartments of the host in conjunction. From this position, the spider is eaten from the inside out, with the vital organs remain only spared. By the end of the larval stages of the spider is completely blown out. Hibernation takes place in the empty host skin, which then pupate in the soil. The dolls are strongly curved and in some species have thorns in the chest area.

Fossil evidence

Fossil ball flies are extremely rare. The oldest evidence comes from the Upper Jurassic of Kazakhstan. The few of Baltic amber ( Eocene, about 40-50 million years old ) and Dominican amber ( Miocene, 15-40 million years) known specimens belong to genera which are closely related to living in South Africa and South America extant representatives of this family are.