THE SAW FLIES. 7 



in both of which regions the typical genus Sir ex is represented by large species. The best known 

 European species, which is common in some parts of Britain, is the great Tailed Wasp (Sirex gigas, 

 figured on p. 353, Vol. V.), a formidable-looking insect, of which the female often measures nearly 

 an inch and a half in length. The general tint is black, with the antennae, the sides of the 

 head behind, and the tibiae and tarsi reddish-yellow, and the base and apex of the abdomen 

 yellow. In the male the abdomen is reddish, spotted with black at the sides and apex. The 

 maxillary palpi in this and other species of the genus are rudimentary. The general wasp-like 

 aspect of this insect is sufficiently recognisable in our figure to explain the popular 

 denomination that has been applied to it ; indeed, many people mistake it for a Hornet, which 

 they know to be a large Wasp, the long ovipositor of course being regarded as a peculiarly 

 formidable sting. This insect lives in pine and fir woods, and the female deposits her eggs in 

 the woody parts of the trees, into which she bores to a depth of over half an inch by means of 

 her auger-like ovipositor. The larvae hatched from these eggs bore deeper into the wood, forming 

 tortuous passages, which gradually become wider as the larvae increase in size^ until they may 

 have a diameter of a sixth of an inch or more. The larvae themselves are fleshy grubs, with a 

 horny head, and six very short thoracic legs. Of abdominal pro-legs there are no traces. The 

 space left behind by the larva is filled up with a mixture of wood-dust and excrement. The 

 question is not quite settled whether the development of the larva is completed within a single 

 year, but this seems to be the most probable supposition ; but as this period of its existence draws 

 towards a close it prepares a somewhat wider chamber for the pupa, and, according to some entomologists 

 (Ratzeburg, &c.), also makes a passage from this chamber to close under the surface of the stem, 

 in order to facilitate the escape of the perfect insect. The latter comes forth in the summer 

 months, and does not appear to enjoy a very long life. Both Sirex gigas and a rather smaller species 

 (S. juvencus), the latter of a general steel-blue colour, which follow the same mode of life, vary 

 greatly in abundance in different years. Occasionally, when the timber into which the larvae have 

 bored has been worked up into furniture, or employed in the woodwork of houses, the perfect 

 insects will in due time emerge, sometimes in such numbers as to cause no small alarm to the 

 human inhabitants. In flying, they produce a loud humming, much like that of the Hoi-net. 



The curious little genus Xiphydria consists of a few species which have short antennae, a round 

 head supported upon a singularly long neck, five-jointed maxillary palpi, and an ovipositor shorter 

 than in /Sirex, although of the same general conformation. The commonest species is Xipkydria 

 cnmelus, a black insect with white spots on the top of the head and along the sides of the abdomen, and 

 with red legs ; it is rather more than half an inch in length. This and the other species of the genus 

 bore as larvae in the wood of various trees (beeches, oaks, poplars, willows, &c). This genus in some 

 respects leads towards the next family, and this is still more the case with another genus (Cephus), 

 one species of which (C. pygmceits) attacks different kinds of grain-plants, the female boring into the 

 green haulm at one of the uppermost knots, and depositing an egg there. The larva hatched from this 

 egg is almost footless, but it is able to make its way about in the narrow passage of the interior of 

 the haulm, the inner layers of which constitute its food. The presence of this insect may be recog- 

 nised in the field by the condition of the ears of corn ; those of the stalks infested are light, and 

 stand upright, while their healthy neighbours are heavy and bent down. When full grown, about 

 harvest, the larva makes it way to the lowest part of the straw, and there encloses itself in a silken 

 cocoon, in which it passes the winter, only passing to the pupa state a little before the emergence of the 

 imago, which takes place about May. 



FAMILY TENTHREDIXID^E. 



A much more extensive family than the preceding is that of the Tenth redinidae, or Saw Flies, the 

 latter name referring to the peculiar form of their ovipositor. Instead of being a piercing or boring 

 instrument, as in all the preceding families, consisting of an upper channelled piece and two slender 

 pieces closing the channel below, and thus completing the egg-canal, the ovipositor in the Saw Flies is a 

 saw-like blade occupying the apical cleft of the abdomen, and composed of two lateral pieces only. 

 What the precise constitution of this ovipositor may be is rather doubtful, but the two lateral serrated 

 pieces would seem to represent the two inferior bristles of the other ovipositors of Hymenoptera, the 

 impaired median piece being undeveloped. The antennae are usually short, frequently more or less 



