THE HORN-TAILS 



(Super-family Siricoidea.) 



These insects form an old series of Hymenoptera, known as 

 the wood-eaters Xylophaga. They are distinguished from the 

 true saw-flies by the fact that the foreshanks have only one spur 

 at the tip instead of two. They have the same broad abdomen 

 and broad head and thorax. 



The group includes the families Oryssidae, Siricidae, Xiphy- 

 driidae and Cephidae. The larvae of all of these insects are wood- 

 borers, living in the stems of plants, and even in the trunks of 

 trees. The adult flies are called horn-tails, because the end of 

 the body usually bears a spine or horn. The ovipositor is fitted 

 for boring instead of sawing, and with it the female bores into 

 woody tissue and lays her eggs. The group is not a very large 

 or a very important one, although it contains many common 

 species. A noted example is the European Cephus pygmceus, 

 which bores into the stems of wheat. This species was acci- 

 dentally introduced into this country some years ago, and is now 

 found in portions of Canada and New York State. Its damage, 

 however, has not attracted the attention of farmers of late. The 

 large pigeon Tremex (Tremex columba) is a not uncommon 

 enemy to shade trees in certain of the northern states. It attacks 

 the elm, oak, sycamore, and several varieties of maple. The 

 holes of this borer may be recognized by their regular, evenly-cut 

 shape, about the diameter of a lead pencil. Isolated shade trees 

 along roads and in streets are favorite habitats. The writer, as a 

 boy, saw them in great numbers in the maple trees on the 

 grounds of the old Ithaca Academy, at Ithaca, New York. In 

 midsummer a large number of females would be seen boring 

 into the trunk of a single tree, laying their eggs. The female 

 plunges her borer perpendicularly into the trunks, holding it at 

 right angles to the abdomen. The insertion requires evidently 

 great muscular effort, and the egg is deposited at the bottom 



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