1911 Encyclopædia Britannica/Harvester

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7425571911 Encyclopædia Britannica, Volume 13 — HarvesterReginald Innes Pocock

HARVESTER, Harvest-Spider, or Harvest-Man, names given to Arachnids of the order Opiliones, referable to various species of the family Phalangiidae. Harvest-spiders or harvest-men, so-called on account of their abundance in the late summer and early autumn, may be at once distinguished from all true spiders by the extreme length and thinness of their legs, and by the small size and spherical or oval shape of the body, which is not divided by a waist or constriction into an anterior and a posterior region. They may be met with in houses, back yards, fields, woods and heaths; either climbing on walls, running over the grass, or lurking under stones and fallen tree trunks. They are predaceous, feeding upon small insects, mites and spiders. The males are smaller than the females, and often differ from them in certain well-marked secondary sexual characters, such as the mandibular protuberance from which one of the common English spiders, Phalangium cornutum, takes its scientific name. The male is also furnished with a long and protrusible penis, and the female with an equally long and protrusible ovipositor. The sexes pair in the autumn, and the female, by means of her ovipositor, lays her eggs in some cleft or hole in the soil and leaves them to their fate. After breeding, the parents die with the autumn cold; but the eggs retain their vitality through the winter and hatch with the warmth of spring and early summer, the young gradually attaining maturity as the latter season progresses. Hence the prevalence of adult individuals in the late summer and autumn, and at no other time of the year. They are provided with a pair of glands, situated one on each side of the carapace, which secrete an evil-smelling fluid believed to be protective in nature. Harvest-men are very widely distributed and are especially abundant in temperate countries of the northern hemisphere. They are also, however, common in India, where they are well known for their habit of adhering together in great masses, comparable to a swarm of bees, and of swaying gently backwards and forwards. The long legs of harvest-men serve them not only as organs of rapid locomotion, but also as props to raise the body well off the ground, thus enabling the animals to stalk unmolested from the midst of an army of raiding ants.

Fig. 1.—Harvest-man (Phalangium cornutum, Linn.); profile of male,
with legs and palpi truncated.
   a Ocular tubercle. d Sheath of penis protruded.
   b Mandible e, Penis.
   c, Labrum (upper lip).   f, The glans.

 (R. I. P.)