The locust has of recent years been extensively planted for post timber. It is very easily propagated from seedlings and grows rapidly. It is adapted to all kinds of soil, except a wet one. It prefers a well drained soil and seems to grow as fast in a loose clay soil as in a black loam. When used for forest planting the spacing should be from 5 × 5 feet to 8 × 8 feet. The spacing should be governed by the quality of the soil, and the amount of pruning that can be done. The locust has the habit of having the terminal to end in a fork and having one or more very large side branches. The best management requires that the very large side branches be removed as soon as they are noted, and one part of the terminal forks be cut off. The locust until recently gave great promise of being an important tree for planting sterile, washed and eroded slopes, on which it usually thrives and in many cases grows thriftily. However, reports from all parts of the State show that locust groves wherever planted are being killed by the locust body borer. The locust has also been attacked by the twig borer, bag worm and the leaf miner. At present there are no known economic means of controlling these destructive pests, and until they can be controlled, the planting of locust for commercial purposes will not prove profitable. =SIMARUBÀCEAE.= The Quassia Family. =AILÁNTHUS.= Tree of Heaven. =Ailanthus altíssima= (Miller) Swingle. Tree of Heaven. Stink Tree. (_Ailanthus glandulosa_ Desfontaines). Plate 110. Medium sized trees with dark gray bark, thin, rough or fissured on old trees; branchlets very robust; twigs smooth; leaves compound and very large, especially on coppice shoots, usually about 4-6 dm. long, odd-pinnate, arranged spirally on the branchlets; leaflets 13-41, ovate-oblong, acuminate, oblique at base, entire or with a few blunt teeth toward the base, smooth or hairy when they unfold, becoming smooth at maturity, dark green above, lighter beneath; flowers appear in June in large terminal panicles, the staminate and pistillate on different trees; fruit maturing in autumn, consists of many light brown, twisted and broadly-winged samaras which are about 1 cm. wide and 4-5 cm. long. =Distribution.=--A native of China. Introduced and spreading in cities, and into fields and woods in the southern part of the State. The most notable occurrence is in Jefferson County on the wooded bluffs of the Ohio River between Madison and Hanover.