426 



Garden and Forest. 



fNUMBER_237. 



I 



Entomological. 



Notes on Two Troublesome Borers. 



F William Cobbett, that enthusiastic Englishman who so 

 ardently praised our common Locust (Robinia Pseudacacia) 

 and advised its general introduction into Britain and Europe a 

 centurv ago, could have had a few years' experience with the 

 borer which almost renders the successful cultivation of the 

 tree in New England a hopeless task, he would probably have 

 qualified his expressions of admiration and commendation. 

 But the Locust is now a common tree all over Europe, in 

 many parts of which there are trees of fine proportions, and 

 all, a'pparently, unattended or unaffected in the least by our 

 handsome brown and golden-yellow banded beetle (Cyllene 

 Robinia;) which does so much mischief as a borer in the early 

 stages of his life. The insect has apparently not yet been in- 

 troduced into Europe, and there seems to be no reason or 

 probability that it should ever be taken there. The only danger 

 lies in the importation of young infested trees or affected lum- 

 ber. But, excepting perhaps some peculiar varieties or forms 

 which may be sent out by her nurserymen, or some rare allied 

 species, plants are now never imported, for the species has be- 

 come almost like a weed in some parts of the Old World. 



Besides affecting the common Locust, this borer is also very 

 injurious to the Clammy Locust (R. viscosa), the Rose Acacia 

 (R. hispida), and in the Arboretum it proves a serious foe in 

 the successful cultivation of the newly introduced R. Neo- 

 Mexicana from New Mexico. In fact, it appears more partial 

 to the last species than to either the Clammy Locust or the 

 Rose Acacia. 



We are more frequently asked about this pest than almost 

 any other. Like most other borers, this is a very troublesome 

 insect to combat. It is usually more destructive to trees in the 

 open and sunlight than to those growing thickly together in 

 groups or woods. The best, and, in fact, the only suggested 

 remedies are preventive. To give the trunks and larger 

 branches a thick and thorough coat of whitewash, with a large 

 proportion of soap in it, is the best we can do ; and where idle 

 children abound it would be an excellent plan to have them 

 daily collect all the showy beetles to be found on the trunks of 

 the trees during the season of ovipositing. It has even been 

 suggested that children might collect the beetles from the 

 flowers of Golden-rod, to which they seem very partial, and 

 they are also to be found on Sunflowers, probably because the 

 colors are protective. It seems to me that this would be less 

 satisfactory than collecting directly from the bark of the trees 

 they infest. 



The beetles are very active, and when alarmed or pursued 

 they will run surprisingly fast or will take to flight. It is gen- 

 erally stated in writings that the beetles are to be looked for in 

 early September, but they should be watched for sooner, as 

 many of them emerge in the latter part of August. Without 

 having noticed or looked for them earlier, I found the beetles 

 ovipositing on August 23d, this season. The eggs are quite 

 large, much larger than might generally be imagined, of a 

 dull white color, oblong and soft, and are to be found just un- 

 der the edges of the roughest bark, or more particularly in 

 places where the bark has been broken and where small limbs 

 have been cut or broken off. Around the openings of their 

 own burrows are also favorite places of the beetles in dispos- 

 ing eggs. 



It will thus be seen that in applying any form of wash to the 

 trees to prevent egg-laying it is extremely important to apply 

 it thoroughly and thickly to all the rtjugher parts, from well up 

 among the branches to very close to the ground. - In this lati- 

 tude it would appear that the wash should be applied as early 

 as from the 20th to 25th of August. We have known the plan 

 of cutting down badly infested trees to be practiced, trusting 

 to suckers to come up and replace them, but when this is done 

 the diseased wood should be burned before midsummer to 

 prevent the escape of the pests within it. 



Of course, it will be difficult to keep the pests in check in 

 districts where Locusts abound everywhere unless radical 

 measures are adopted, but where the trees can be easily num- 

 bered, as in most New England and northern towns, they 

 could with a little care be kept comparatively free from inju- 

 ries. It is particularly important to save and protect the trees 

 when young, for the ravages of the borers then sooner cause 

 their death or so weaken the stems that they break in high 

 winds. 



A Blackberry-root borer has appeared in the Arboretum in 

 large numbers this season, causing much injury to the various 

 species of this section of the genus Rubus. While it may have 

 been abundant other years it has remained unnoticed, and the 



death of the canes has been invariably attributed to winter-kill- 

 ing. An examination of the stumps of the dead canes cut off 

 at the ground, this spring, shows a burrow and pupa in almost 

 everyone, the empty pupa-casesticking out of holes in the sides 

 of the canes at an inch or two above the ground. The insects 

 from these pupae are little day-flying moths, known as ^geria 

 rubi. Both at rest and when flying they have a startling re- 

 semblance to our common wasp or "yellow jacket," for which 

 they might very easily be mistaken by the casual observer. 

 The moths were found in considerable numbers on August 

 23d, some of them just emerged, and appearing more abun 

 dantly several days later, and when the Blackberry-bushes 

 were vigorously shaken on a warm afternoon many would 

 arise and flutter around. The eggs are deposited soon after 

 this, near the root of the cane ; on hatching the young borers 

 work downward, burrowing in the crown or upper portions of 

 the larger roots ; they remain dormant all winter, renewing 

 their activity in spring, and finally boring up the canes a lit- 

 tle way or merely to the surface of the crown of the root in 

 preparation for emergence late in August. The full-grown 

 larva is about an inch long, of a light yellowish color, with a 

 brownish head. This insect has been called a Raspberry-root 

 borer, but in the Arboretum I have so far only noticed it as 

 infesting roots of Blackberry, although Raspberry-plants are 

 only a few feet distant. There appears to be no remedy for 

 this pest but digging up and destroying the old roots and re- 

 placing them with clean young stock. If the old roots are 

 taken up in the spring or autumn and burned, the whole brood 

 of borers will be destroyed, and new invasions will necessarily 

 have to come from other plantations or wild plants. Those 

 who have been troubled with their Blackberry-canes not 

 bursting into vigorous growth in the spring would do well to 

 examine the crowns of the roots for borers before jumping to the 

 conclusion that the variety of Blackberry was lacking in hardi- 

 ness to withstand the cold of winter. 'r r ^ h 



Arnold Arboretum . J- ^' fClCfi' 



Foreign Correspondence. 

 The Rock-garden at Kew. 



ONE of the most interesting and popular of the attrac- 

 tions at Kew is the rockery or rock-garden, a portion 

 of which is shown in the illustration on the next page. It 

 was constructed ten years ago on one of the lawns adjoin- 

 ing the hardy herbaceous plant department, near one of 

 the principal entrances to the gardens. The manner of its 

 construction will be gathered from the following extract 

 from the Kew Report for 1882 : "As the surface of the site 

 chosen was perfectly fiat, it was necessary, in order to get 

 any variation of level, without moving large quantities of 

 soil, that the main path through the rock-garden should be 

 sunk. This path was first laid out in a winding course, so 

 as to bring in as natural features the picturesque trees with 

 which the ground was studded. The general idea which 

 was finally worked upon was that of the rocky course of a 

 stream, such as may be met with in some of the side val- 

 leys of the Pyrenees. Such streams dry up after winter, 

 and are bounded by rock-piled banks, amid the crevices of 

 which a copious summer vegetation springs up. Above 

 the rocks an evergreen shrubbery growth descends 

 wherever the soil is of sufficient depth. The path, eight 

 feet wide and 514 feet long at the bottom of the rock- 

 garden, represents the dry bed of such a stream. On , 

 either side fragments of rock .are piled up in a manner as Ij 

 little artificial as was possible to a height of about five feet. 

 Above this the view is limited by shrubberies of Box, Rho- 

 dodendron, etc., rising to a varying height." 



The natural soil of the site chosen was a perfectly pure 

 sand. As much good soil as possible was therefore thrown 

 in behind the rock-bank. As the stones were arranged 

 good soil was worked in beneath and between them. For 

 parts of the banks with a northern exposure tree-stumps 

 were employed. The use of these has been a good deal 

 criticised, but it is not wholly out of keeping with the gen- 

 eral idea, and, as a matter of fact, they prove admirably 

 suited to the growth of the larger and stronger growing 

 species. 



The principle of a rock-garden is to imitate the condi- 

 tions of growth of deep-rooted plants. Almost all sub- 



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