88 MARYLAND AGRICULTURAL EXPERIMENT STATION. 



beetle cuts through the hark and emerges. The burrow made in the 

 solid wood by this insect, is always flattened or elongate-ovoid in shape. 



This beetle produces but one annual generation, the larva requiring 

 l)ut one season for full growth. I have known it to become full-grown 

 and to kill young trees, between the first week in June and the last of 

 September, and only the last year had absolute proof of this limitation 

 of the larval life of the insect, by losing a young sycamore tree, which 

 was planted from the nursery as late as tlie first of June, and which was 

 carefully inspected and showed no evidence of the borer, at the time of 

 planting. This tree was killed by the girdling of the borer by the end 

 of September. 



While the Kound-headed Borer is found in older trees and frequently 

 in trees that otherwise seem to be vigorous, yet it prefers trees of feeble 

 growth or those which are newly transplanted, and those growing upon 

 ridge lands or in plowed orchards, are more liable to attack, tlian those 

 2:rowing on low lands or in orchards seeded to grass. AVith the Flat- 

 headed Borer, however, a great predilection is shown for trees that have 

 been injured in any Avay, and newly transplanted trees from a nursery 

 should be particularly watched. The injury is most apt to take place on 

 the south-west side, whicli is most subject to the so-called "sun scald." 

 In fact, it is doubtful if the young larvi^ or the eggs can withstand the 

 strong floAving sap of a vigorous tree, and in almost every case in my ex- 

 perience, where this borer has done any damage, it has been as a conse- 

 quence of some prior injury. 



REMEDIAL MEASURES. 



A slight discoloration of the tree, a flattening of the bark, a slight 

 exudation of the sap or an extrusion of fresh, saAvdust-like excrement or 

 gnawings, Avill often indicate the presence of these borers, in Avhich case 

 they may frequently be cut out and destroyed, if the Avork is detected in 

 time, or if they have entered the solid Avood, a Avire may be used as a 

 probe to foUoAv and kill the borer, or a little hot Avater or kerosene may 

 be poured into the hole. 



Prevention, hoAvever, is to be preferred in both cases, and alkaline 

 Avashes applied to the trunk, have been found Ijy experience to have a de- 

 terring effect upon the female beetles and to preA-ent their laying their 

 eggs upon the trees so treated. I generally take a bar of hard soap and 

 rub it up and doAvn the trunks of young trees, and place a piece in the 

 principal crotch, alloAving the rains to gradually Avash it doAvn over the 

 trunk. This is a simple preventive method, Avhich Dr. Fitch, many years 

 ago found to be satisfactory, and Avhich I have proved to be so in my 

 own experience. If soft soap is used, the trunk and larger branches may 

 be painted by means of a Avhite-wash brush, the soft soap being reduced 

 to the consistency of thick paint, by the addition of a strong solution of 

 Avashing soda in water. A certain proportion of either of the arsenical 

 poisons in ordinary use, if mixed with such soap-Avash, Avill serve to 

 render the same more permanent and effective, Avhile a good fish-oil soap 



