XXIX. THE LOCUST TREE. 459 



two upper shorter and cohering or approximate. The banner 

 of the corolla is ample, the keel obtuse. The stamens in 2 

 bundles, deciduous. The style is bearded next the free stamen. 

 The fruit is a many-seeded pod, with the seed-bearing edge 

 margined, and with thin and flat valves. 



The locust trees, particularly the Common, are subject to 

 the assaults of many insects. The leaves of the common locust 

 serve as food and habitation to the caterpillars of the Tityrus 

 skipper, a large, brown butterfly with honey-yellow spots, 

 (Harris's Report, p. 224, where is found an interesting account 

 of the habits of the caterpillar). The bark is punctured and 

 the sap sucked by the two-spotted tree-hopper, (Membracis bi- 

 maculata, ib. p. 179). The pea-weevils, (Bruchus pisi, ib. p. 

 55), lay their eggs in the seeds as they do in those of the pea 

 and other leguminous plants ; and the grubs of an Apion beetle, 

 (ib. p. 59,) inhabit the pods and eat up the seeds. The grubs 

 of the painted Clytus beetle, (ib. pp. 86 and 295,) burrow in the 

 bark and devour the soft inner portion, in autumn, and in spring 

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

 trunk, which they traverse by many winding and irregular, 

 upward passages. A small reddish caterpillar (supposed by 

 Dr. Harris to belong to one of the iEgerian sphinges, or to one 

 of the Bombyces, see p. 295 of his Report), lives in the pith of 

 the small branches and trunks of very small trees. The irri- 

 tation causes the twig to swell and become spongy in the parts 

 affected, and easily to break off at these places. The large ca- 

 terpillar of the locust tree carpenter-moth, (Xyleutes Robinice, 

 ib. pp. 296 — 7), bores the tree in various directions, appearing 

 to prefer old and full grown trees. For full accounts of these 

 several enemies of the locust tree, which threaten, if not checked, 

 to exterminate the tree, I must refer to the admirable Report of 

 Dr. Harris. 



Two species of locust, besides the Common, are natives of 

 the southern parts of the country and may be cultivated here : 

 R. viscosa, the Clammy-barked locust, which is a small tree, 

 with large, showy, pale pink flowers ; and R. hispida, the Rose 

 Acacia, a very beautiful flowering shrub. 



