64 



secretions of flowers having been so directed and controlled by man as to obtain the best 

 results for himself. The habits of many ants, wasps, ichneumon-flies and other hymen- 

 optera have been also studied, but there remain vast numbers of which little or nothing, 

 is known, and which afford scope for the observations of all who seek to add to our know- 

 ledge of insect life. 



Hymenoptera are divided into two sub-orders, named respectively Aculeata, or stingers, 

 and Terebrantia, or borers. The first contains the bees, wasps, ants and other insects 

 which have the abdomen (in the females) furnished with a sting to which an irritating 

 poison is applied by special glands. The second contains forms in which the abdominal 

 instrument is so constructed as to be used in sawing slits or boring holes in which the 

 insect may deposit its eggs. It may be conveniently divided into three sections, namely : 

 Entomophaga, or insect-eaters, such as the ichneumon-flies ; Gallicola, or gallformers, con- 

 sisting of a single family ealled Oynipidas ; and Phytophaga, or plant-eaters, containing 

 the saw-flies and horn-tails. 



The Phytophaga, being plant-eaters and consequently destructive and obnoxious^ 

 insects, are of more immediate interest to agriculturists than the other sections. They are 

 divided into two families, Uroceridse and Tenthredinidag. The former contains a limited- 

 number of species, usually of large size, of which the females are provided with a long 

 augur-like borer for inserting their eggs deeply into the wood of the trees in which the 

 larva? feed when hatched. 



The Tenthredinidse, or second family, is that of which the remainder of this paper will 

 treat. It includes the insects popularly known as saw-flies, of which certain species are 

 well-known to every one who has attempted agriculture on even the smallest scale. 



Saw-flies have none of the interesting social, or architectural habits of bees, wasps and 

 ants, and, although highly organized in many points of structure, rank as the lowest of 

 the hymenoptera. They are most obnoxious insects, from the gardener's point of view, 

 because they are all, as larvae, strictly vegetarians, and what the farmer must perforce 

 admire in his customers is, as regards insects, a most undesirable habit. In size they 

 vary from the formidable cimbex, an inch in length, and with a wing expanse of more 

 than two inches, to species no larger than a grain of rice. 



The perfect, or winged, insect differs from the honey-bee in form, chiefly through- 

 having the abdomen sessile, or joined solidly to the thorax, instead, of having the waist 

 constricted so as to almost cut the insect in two. The head is of medium size, generally 

 broad in front so that the large eyes are widely separated. On the top of the head are 

 three ocelli, or single eyes, arranged in a triangle. The mouth is furnished with toothed 

 mandibles, or jaws, which, in the larger species are quite dangerous looking instruments,, 

 although in reality they are quite harmless. The thorax is generally wider than the head, 

 and bears, as in all insects, the organs of locomotion. It is formed of a large number of 

 chitinous or horny plates, all of which have special names, and are of value in technical 

 descriptions, but which need not be here enumerated. The legs are of moderate length, 

 and slender in the majority of species. The wings, four in number, are large and mem- 

 braneous, having comparatively few veins, and being generally transparent. The venation, 

 or arrangement, of the ribs or skeleton, which supports the membranes of the wings, 

 especially the front ones, is of importance as being principally used in the division of the 

 species into genera. The anterior margin (of the front wing) is strengthened by a vein, 

 which expands towards the tip into what is known as the stigma. Behind this are from 

 one to three marginal cells, and behind these three or four sub-marginal ones. The 

 abdomen is sub-cylindrical in form, and, as above stated, is not constricted at its junction 

 with the thorax. It is composed of several distinct segments, the last of which in the 

 female carry in a groove beneath them the characteristic ovipositor. This instrument con- 

 sists of several pieces, but may be briefly described as a pair of horny saw-like plates 

 enclosed in a pair of outer sheaths. 



It is from the possession of these minute saws that the insects have received the 

 popular and, as is frequently not the case in popular nomenclature, appropriate name of 

 " Saw-flies." With this complex ovipositor the female saws slits in the stems or leaves of 

 plants, in order that she may deposit therein her eggs. In some species, however, as in the 

 imported currant saw-fly, the apparatus is so feeble, or aborted, that the insect has to- 



