384 CLASS Yin. 



palps four- or five-jointed, labial with two or three joints. Thorax 

 gibbous, with mesothorax very large. Abdomen compressed. 

 Borer extremely slender, with three setas, concealed, rolled spirally, 

 between a bivalve sheath, exsertile from the last ventral chan- 

 nelled segment of abdomen. 



Gall-wasps. The females of this family pierce different parts of 

 plants (leaves, leaf-stalks, buds, &c.) and lay an egg in the wound. 

 The irritation thus produced causes the sap to flow in greater abun- 

 dance to the wounded part, and thus different excrescences, often of 

 very singular kinds, arise, which serve the larva both for food and 

 habitation. The form of the excrescences is different for different 

 species, and may serve for recognising and distinguishing them. 

 The larvae, bent into a semicircle, lie as thick white maggots 

 in the cavity of these excrescences. Some species undergo their 

 metamorphosis in this situation ; others leave it before becoming 

 nymphs, and change under ground. It is true that species also of 

 Chalcides are found in these excrescences, which were formerly 

 placed with species of Cynips in one genus, and to which GEOFFROY 

 gave the name of Cynips exclusively, which occasioned much 

 confusion in the nomenclature : they are ichneumons which have 

 taken the place of the natural inhabitants. 



Gall-wasps, although living upon vegetable food, have neverthe- 

 less a great affinity with the Ichneumonides, and this is shewn more 

 distinctly by the fact that some species (Allotria WESTW.) really 

 live like ichneumons in insects (Aphides), without on that account 

 differing from the rest of the Cynipides by natural characters or 

 organisation (WESTWOOD, Introd. to modern Classificat. of. Ins. n. 

 p. 132, RATZEBURG, Die Forst-Insecten, m. p. 54). 



To the excrescences, caused by gall-wasps, belong also the gall- 

 nuts or gall-apples, of which those that come from the East (from 

 Aleppo) are iu most esteem. They consist, besides gallic acid, in 

 great measure of tannin, and are consequently very astringent. Hence 

 their use in medicine. Their property of forming a black pre- 

 cipitate with salts of oxyde of iron, causes these gall-nuts to be 

 employed in the preparation of writing-ink. 



Comp. on this family : MALPIGHIUS de Gallis, in Anatomes plantar-urn, 

 parte alterd (Operum ed. Londin. 1686, fol. Tomo n. pp. 17 38); 

 OLIVIER, Encycl. m&th., Hist. not. des Ins. v. 1790, pp. 772 792, 

 BRANDT u. KATZEBURG, Medizin. Zoolog. n. s. 144158; BOYER DE 

 FONSCOLOMBE, Description des Ins. de la fam. des Diplolepoire.* </"! .SY 



