CLASS I. INSECTA: ORDER 3. II YMENOPTEE A. 



569 



SECT, Cynips gal-Ice tinctorice. The females of these puncture the leaves, buds, and other parts 

 of plants and trees, depositing an Qgg in the wound, accompanied probably by some irritating 

 fluid, which causes a diseased growth in the part, and thus produces the excrescences known as 

 galls. AYithin this domicile the larva lives, feeds, and attains its maturity. Here it also under- 

 goes its transformations, and it is not until its arrival at the perfect state that it eats its way out, 

 and becomes a free denizen of the air. 



The forms of the galls vary according to the plant on which they are found, and the species 

 of gall-fly by whose puncture they are caused. The oak is especially subject to the attacks of 

 these insects. The leaves are often covered with small round galls, produced by the Cynips 

 quercus-folU, and several other species attack those organs; while the well-known oak-apples 

 are produced by a species — Cynips terminalis — which deposits its eggs in the extremities of the 

 shoots. Other species of oaks are equally infested by these creatures, one of which, noticed 

 above, produces the well-known and important galls of commerce, often called Nut-Galh, 

 and used for making ink and as a chemical test. The Dead Sea Jpjjles, which have been 

 the subjects of frequent controversy, are also galls, produced by the puncture of a small insect 

 described by Mr. Westwood under the name of Cynips insana. The spangles of the oak-leaves 

 are also produced in this manner. These excrescences usually contain only a single larva ; but 

 in some cases a large family of grubs are concealed in a single gall. A few species are parasitic 

 in their habits. 



THE SECURIFERA. 



Under this name are included a large number of insects — the Phyllophaya, known as Saw- 

 Flies, and the Xylophaya, or W^ood- Gnawers^ known as Tailed Wasps. The females of the former 



have the ovipositor in the form of a fine, sharp 

 saw ; with this she cuts numerous minute slits 

 in the stems or leaves of plants, in each of 

 which she lays an egg, accompanied by a drop 

 of fluid, which prevents the closing of the 

 wound, and in some cases the irritation thus 

 induced causes the formation of a gall, within 

 which the larvje live and feed. As a general 

 rule, the larva), when hatched, leave their shelter 

 and feed upon the leaves of plants. The species 

 are generally confined to certain kinds of plants, 

 to which, when they are produced in great num- 

 gff^if^ bers, they often do immense mischief. Thus 

 '^ the larvfe of the Athalia centifolice, known to 

 farmers as the Nigger or Black Caterpillar^ have 

 occasionally done incredible damage to turnips 

 in Europe ; and those of another species, the 

 Nematus grossularice, are not less destructive to 

 gooseberry-bushes. The larva3 of other species 

 infest fruits, living and feeding in the interior, 

 and causing them to fall off" while still immature. 

 They are almost always furnished with pro-legs 

 in addition to the thoracic membei's. The Cim- 

 hex ulmi is an American species, frequenting elm-trees. 



In the Tailed Wasps, Horntails, or Wood Wasj^s, also often called Borers in this country, 

 the ovipositor projects from the abdomen, and is composed of serrated bristles, with which they 

 perforate timber. On the continent of Europe the Si^rx gigus often appears in immense num- 

 bers, and does great damage in this way. The Pigeon Tremex of Harris, Sirex cinctus, is one 

 of the American species; this sometimes completely riddles the trunks of maples, button- 

 woods, &c. 

 Vol. II.— 72 



THE SIREX GIGAS. 



