380 FIFTH REPORT OF THE ENTOMOLOQICAL COMMISSION. 



hovered around thein. For fifteen years or more some large buttou- 

 wood trees in Cambridge have been visited by them in the same way.'^ 



Prof. J. A. Lintuer, State Entomologist of New York, has communi- 

 cated the following facts to the Country Gentleman : 



Somethiug has attacked a large maple tree in front of my house. The trunk looks 

 as if a large dose of buckshot had been shot into it, having fifty or more clean holes 

 about one-eighth of an inch across. Can you tell me what to do to save the tree? 

 I have seeu a large insect like a wasp, with several boring arrangements at least 

 3 inches long each, inserting these into the tree. Do these cause the mischief? 



W. S. J. 



Poughkeepsie, N. Y. 



[Answer by Prof. J. A. LiDtner, State Entomologist.] 



The several holes in the maples have been bored by the larvae of Trernex columhay 

 one of our saw-flies and the largest of our species. The female is armed with a stout 

 borer, the end of which is furnished with teeth, by means of which it is thrust 

 through the bark into the wood, to the depth sometimes of half an inch and the egg 

 inserted. Occasionally the female is unable to withdraw her borer, when she may 

 be captured, during the months of Juiy and August, struggling to escape from the 

 tree. The larva hatching from the egg burrows into the trunk, and when it has 

 nearly matured, by the aid of its strong jaws, it enlarges its round burrow outwardly 

 to the size often of a small lead pencil, to permit the escape of the perfect insect. 



While maples are more frequently attacked by this insect than other trees, it is 

 also found in oaks, elms, and sycamores, and more commonly in those planted as 

 shade trees in streets or about dwellings. Unless it is very abundant it does not 

 destroy the tree that it attacks, but the holes soon heal over without serious injury 

 following. Its injuries are far less ser ions than are those of another borer of the maple, 

 the GlycoMus speciosus (Say), a beautiful long- horned beetle, the black wing-covers 

 of which are prettily ornamented by a yellow VV> ^^^ by other yellow bands and 

 spots. 



" The female, when about to lay her eggs, draws her borer out of its 

 sheath, till it stands perpen dicularly under the middle of her body, 

 when she plunges it, by repeated wriggling motions, through the bark 

 into the wood. When the hole is made deep enough, she then drops 

 an egg therein, conducting it to the place by means ofthe two furrowed 

 pieces of the sheath. The borer often pierces the bark and wood to 

 the depth of half an inch or more, and is sometimes driven in so tightly 

 that the insect cannot draw it out again, but remains fastened to the 

 tree till she dies. The eggs are oblong- oval, pointed at each end, and 

 rather less than one-twentieth of an inch in length." Harris adds, what 

 has been observed frequently by others since his time, that these larvae 

 are often destroyed by the maggots or larvae of two singular ichneu- 

 mon flies {Rhyssa atrata and lunator). These are the largest known 

 ichneumon flies ; they are provided with long, slender borers or ovi- 

 positors from 3 to 4 inches in length, which they thrust into the 

 deep holes made by the Tremex borers, in the bodies of which they 

 insert an egg. 



(We have, however, observed one of these Rhyssce engaged in 

 ovipositing in an elm tree infested with the larvse of Compsidea 

 tridentata.) 



