SlCl'l'KMHP'.k 25, 1889. 1 



Garden and Forest. 



461 



southern Indiana will give an idea, at least, of the dimen- 

 sions to which this tree can attain under favorable condi- 

 tions ; and brings out admirably the peculiar character of the 

 distinctive bark, to which habit is due the popular and famil- 

 iar name of the species. The Shell-harks in this particular 

 region, Mr. Ridgway notes {Proc. U. S. Nai. Mits., 1882, 

 77), are sometimes 150 feet high, with trunks four or five 

 feet in diameter, and bare of limbs for seventy or eighty 

 feet ; and even larger trees can be found in the western 

 and still almost untouched forests of eastern Tennessee and 

 western North Carolina. But these large trees are doomed, 

 and before many more years have passed every Hick- 

 ory-tree of sufficient size and proper quality will have been 

 sacrificed to supply the ever-increasing demands which the 

 industries of men make on this tree. The area of the re- 

 gion in which the Hickory grows to perfection is really 

 small in comparison with the demand for it; and when no 

 substitute can be found for a particular wood it must in 

 time be exterminated however abundant the natural sup- 

 ply, unless measures are taken to increase and perpetuate 

 it artificially. And it would appear that of all our trees the 

 Hickory is the one which should be planted wherever suit- 

 able land can be spared for it ; and it should be protected 

 and cherished, in view of the ever-increasing demands the 

 world is making and must continue to make on this tree. 



Entomological. 

 A New Enemy of the Elm. 



[Gossyparia Ul»ii.) 

 T N the last (August) number of Insect Life, Mr. L. O. Howard 

 -^ has an interesting paper, accompanied by some excellent 

 Jigures, on tliis new Elm-pest, Ijelonging to the Coccid or 

 "scale insect" tribe. The article is entitled "A Newly-im- 

 ported Elm bisect," and it gives a good summary of what is 

 known of the life history of tiie insect which is considered as 

 having been introduced from Europe on European Elms, and 

 which lias been found in several places in New York State and 

 also about Boston and in Washington. Near Boston it was 

 tirst noticed in the Arnold ArlioretLun, in the summer of 1887. 

 Since then it has increased very much, and has been found 

 quite abundantly in many places in the vicinity of the city. 

 'Although first found on the Slippery YAxn (^Ulmus fiilvd),\i 

 lias latterly been more frequently observed on the American 

 Elm {^U. Americana) than on any other species. It also attacks 

 U. raceinosa as well as the European species, U. cainpestris 

 and U. inontana. 



The accompanying illustration from a photograph will be of 

 assistance in recognizing the pest, and will give an idea of its 

 appearance at one stage of its existence. The photograph was 

 taken about June 20th, -which is the season when the coccids 

 may be most readily detected, and it represents fully grown 

 females on the bark of a young Slippery Elm. The roimd of 

 tlieir existence may be described as follows : 



These females are viviparous, and, in this vicinity, repro- 

 duction begins about June 20th. All the females do not ma- 

 tinee at the same time, so that the young continue to come 

 forth for a couple of weeks. The young larva is elongated, 

 oval in shape, and of a clear yellow color, and, under the 

 microscope, a numlier of spines on the back and sides may be 

 seen, as well as the six-jointed antennie. As soon as they es- 

 cape from the parent body the young begin moving actively 

 about upon the trunk and branches, and sometimes collect in 

 great numbers on the under side of the latter. Most of them 

 soon find their way to the lea\'es, where they fix themselves 

 and become qiuescent, feeding upon tlie juices for four or 

 five weeks, or, in some cases, for a much longer time. On 

 some trees, whicli have no pubescence or bristles on the 

 young shoots or twigs, many of the insects settle about the 

 crevices of the buds, etc. On the leaves they are often foimd 

 on both the upper and lower surfaces, either in the crevices 

 made by, or close along the sides and angles of, the midrib 

 and principal veins. On Ulmus Americatia and U. racemosa 

 they are found most abundantly upon the under surface, and 

 in other species they occur on the upper or lower surface ac- 

 cording to the amount of pubescence which prevails. They 

 are less numerous where it is densely bristly. Late in July 

 and during August they cast their skins, assume a permanent 

 reddish or brownish color, and become active once more. 

 The main color is often much obscured by a fine and easily- 

 removed gray or white waxy powder, which is secreted by, and 

 carried upon, the many spines with which the back is covered. 



Nearly all of them return to tlie branches and trunk, wliere 

 they settle themselves in crevices of the Ijark. Here they re- 

 main .during the autumn and winter. If the days are warm in 

 late April and early May they begin to move again, and soon 

 afterwards changes of skin take place and small white cocoons 

 are made, or, as Mr. Howard says, " the females cast their last 

 skin and the males foi'm their cocoons." 



They issue forth within a week or ten days. Two forms of 

 males have been noticed ; the first, about two millimeters (say 

 .08 of an inch) in length, has rudimentary or unexpanded 

 wings, but appears to be perfectly developed in other re- 

 spects, and the other, which comes forth a few days later, has 

 broad, perfectly developed wings, and also differs from the 

 imperfect male in having a more slender body and two long, 

 slender, white filaments projecting from the anal segment. 

 Soon after this the females fix themselves for the last time to 

 the bark of the trunlc or branches and continue to suck the 



sap of the tree and 

 ,Sfr*^«.., increase consider- 



ably in size, 

 especially in di- 

 ameter. 



A white waxy 

 substance is sec- 

 reted, which after- 

 ward becomes so 

 ti b u n d a n t as to 

 form a sort of 

 cushion beneath 

 and around the 

 sides of the in- 

 sects, giving them 

 the conspicuous 

 appearance seen 

 in the illustration. 

 Here they remain, 

 and in the latter 

 part of June the 

 living young be- 

 gin to swarm 

 forth; the moth'er 

 insect gradually 

 becomes smaller, 

 shrivels and dies, 

 and, after a time, 

 the waxy cushion 

 becomes dull and 

 wears away, al- 

 though traces of 

 it may remain for 

 many months. 



D u ring all the 

 feeding period 

 of their existence 

 the coccids throw 

 out a sort of "honey dew," in verv minute drops, which, 

 falling upon the trunk, liranches and lower leaves of the tree 

 causes them to become blackened, and many ants, wasps. Hies 

 and other insects are attracted to the sweet food. When dry 

 this may be scraped from the leaves in sooty-like flakes. 



Trees that are much infested with these insects make their 

 presence known at a distance of several rods by a peculiar 

 sweet, somewhat pungent, though not unpleasant, odor. An 

 odor much like it may lie noticed when drying green leaves 

 of Ulmus fiilva. On old trees the insects cannot get nourish- 

 ment through the thick, corky bark of the trunks, and so 

 ascend to the higher parts and branches, where they are not 

 easily discovered. In some cases they may be a cause of the 

 unhealthy appearance of trees. When abundant, they greatly 

 injure the vitality of yoiuig trees if they dc) not destroy them. 



No systematic experiments with insecticides have as yet 

 been tried, but an application in June of whale-oil soap and 

 kerosene, made pretty strong and applied with a stiff brush, 

 appeared to kill all that were thoroughly washed, but some on 

 the small branches escaped, so that enough were left to thickly 

 colonize the tree again within a year or two. Thoroughly 

 spraying the trees with kerosene emulsion, at a season when 

 the insects are active and tender, might lead to more satis- 

 factory results, liut the cliances are that some would escape. 



It has been noticed that a few of the insects sometimes re- 

 main on the leaves until they fall in the autumn, and in this 

 way they could be carried from one tree to another. When 

 active they may easily be carried to widely-separated localities 

 upon the feet of birds. <v /^ fy / 



Arnold Arboretum. J • G. Jack. 



Y\%. i29.^Gossyparia Uliai.— Full-grown females. 



