out their hosts; instead, the first-instar larva is a planidium. Females lay large number of eggs, up to 5,000, and after hatching, the planidia seek out spiders. They do not resemble the triungulin of most beetles with a hypermetamorphosis, but do resemble the triungulin of Stylops. The larva can move with a looping movement like a leech or inchworm, and can leap several millimetres into the air. When a spider contacts an acrocerid planidium, the planidium grabs hold, crawls up the spider's legs to its body, and forces its way through the body wall, usually at an articulation membrane. Often, it lodges near a book lung, where it may remain for years before completing its development. Mature larvae pupate outside the host. The adults of most species, like various members of the Tabanidae, Nemestrinidae, and Bombyliidae, are nectar feeders with exceptionally long probosces, sometimes longer than the entire body length of the insect. Unlike the other families, however, when not deploying the proboscis for feeding, the Acroceridae carry it lengthwise medially beneath the body, instead of projecting forward. As a result, the proboscis might escape casual notice, though careful inspection may reveal it projecting slightly behind the abdomen. Flies are usually found in small numbers on plants in July and August in the Palearctic realm. References Further reading Species lists Palaearctic Nearctic Japan Australian and Oceanian List of soldierflies and allies of Great Britain Identification Sack, P., 1936. Acroceridae. In: Lindner, E. (Ed.). Die Fliegen der Paläarktischen Region 21, pp. 1–36. Keys to Palaearctic species, but in need of revision (in German). Narchuk, E.P., 1988. Family Acroceridae. In Bei-Bienko, G. Ya, Keys to the Insects of the European Part of the USSR Volume 5 (Diptera) Part 2, English edition. Keys to Palaearctic species, but in need of revision. Przemysław, Trojan, 1962. Acroceridae. In Klucze do oznaczania owadów Polski 28, 23, 1–17. Muchowki = Diptera, 54/58. Warsaw: Państwowe Wydawnictwo Naukowe. External links Family description, illustrations Images at Diptera.info Images and information at BugGuide Family Acroceridae at EOL Acroceridae in Italian Wing venation Brachycera families