COMMON LOCUST. 205 



plants will sometimes produce annual shoots from six to eight feet long for seve- 

 ral years after planting ; whereas, in wet or poor soils, they will not exceed one- 

 fourth of this length. After the first ten or twelve years, upon good land, the 

 locust will probably have attained a height of fifteen or twenty feet, with a diam- 

 eter of three or four inches; and then its growth, in general, becomes very slow; 

 and few trees, at the expiration of fifty or sixty years, will be found over fifty 

 feet in height, and one foot in diameter. 



Insects, Accidents, c5'c. The Robinia pseud acacia, in Europe, is very free from 

 the attack of insects ; but in those parts of the United States where this tree is cul- 

 tivated, it is preyed upon by three distinct species of borers, or wood-eaters, the 

 unchecked operations of which threaten an almost entire destruction of this valu- 

 able tree. Dr. T. W. Harris, in his " Report on the Insects of Massachusetts 

 injurious to Vegetation,"' observes that, "One of these borers is a little reddish 

 caterpillar, whose operations are confined to the small branches and to very young 

 trees, in the pith of which it lives ; and by its irritation it causes the twig to 

 swell, around the part attacked. These swellings, being spongy, and also per- 

 forated by the caterpillar, are weaker than the rest of the stem, which theretbre 

 easily breaks off at these places. My attempts to complete the history of this 

 insect have not been successful hitherto ; and I can only conjecture that it belongs 

 to the vEgerians, or possibly to the tribe of Bombyces." In the same work, he 

 describes a second kind of borer, called Clytus pictus, or the painted clytus. 

 " In the month of September," he says, " these beetles gather on the locust-trees, 

 where they may be seen glittering in the sun-beams, with their gorgeous livery 

 of black velvet and gold, coursing up and down the trunks in pursuit of their 

 mates, or to drive away their rivals, and stopping every now and then to salute 

 those they meet, with a rapid bowing of the shoulders, accompanied by a creak- 

 ing sound, indicative of recognition or defiance. Having paired, the female, 

 attended by her partner, creeps over the bark, searching the crevices with her 

 antennae, and dropping therein her snow-white eggs, in clusters of seven or eight 

 together, and at intervals of five or six minutes, till her whole stock is safely 

 stored. The eggs are soon hatched, and the grubs immediately burrow into the 

 bark, devouring the soft, inner substance, that suffices for their nourishment till 

 the approach of winter, during which, they remain at rest, in a torpid state. In 

 the spring, they bore through the sap-wood, more or less deeply into the trunk, 

 the general course of their winding and irregular passages, being in an upward 

 direction from the place of their entrance. For a time, they cast their chips out 

 af their holes as fast as they are made, but after awhile, the passage becomes 

 clogged, and the burrow more or less filled with the coarse and fibrous fragments 

 of wood, to get rid of which, the grubs are often obliged to open new holes 

 through the bark. The seat of their operations is known by the oozing of tha 

 sap and dropping of the saw-dust from the holes. The bark around the part 

 attacked begins to swell, and in a few years the trunk and limbs will become 

 disfigured and weakened by large, porous tumours, caused by the clforts of the 

 trees to repair the injuries they have suffered." According to the observations 

 of a writer in the " Massachusetts Agricultural Repository and Journal," vol. vi., 

 the larvae of this insect attain their full size by the '2Uth of July, soon after 

 which, they pass into the pupa state, I'ud are transformed into beetles early in 

 September. The third class of borers which attack this tree, is the Xylcutes 

 robinia?, or locust-tree carpenter moth, of Harris; or the Cossus robiniic, 

 described and figured by Professor Peck, in the Vth volume of the " Massachu- 

 setts Agricultural Repository and Journal." According to Michaux. the ravages 

 of these insects were first observed about sixty years ago; but their habits were 

 not generally known before the year 18U3, when they first attracted the atten- 

 tion of Professor Peck, of Harvard University. He observed several locust-trees 



