THE MONTHLY IUU.ETIN. 



m 



caused l>y ;i fungus glowing in the wood. There is no way of removing the fungus 

 once it lias entered, ami no known way of preventing it from entering. It seems to 

 be much more prevalent in irrigated, rapid growing orchards than in nonirrigated, 



Slower growing ones. This is particularly noticeable in orchards intercropped with 

 tomatoes which require much irrigation and permit comparatively little cultivation. 

 While this disease can not l>e wholly prevented much can be done to keep it down. 

 Keep the soil moisture constant and moderate by repeated cultivations rather than 

 by Irrigation. If the land must be irrigated do not wait until the growth of the 

 trees has been checked and do not apply an excessive amount of water. Endeavor 

 to keep the trees growing constantly but not too rapidly during the entire growing 

 period. "Blaekheart" seldom occurs in nursery stock, but a careful inspection 

 should be made when the trees are headed back for planting and any thrown out 

 which are diseased. 



THE APPLE LEAF-MINING CASE-BEARER 



(Coleophora volckei, n. sp. 1 ) 



By W. H. Volck, County Horticultural Commissioner, Watsonville, Cal. 



For several years past a certain type of injury has been more or less in evidence 

 on Pajaro Valley apples at harvest time. This injury consists in one or more small 

 punctures in the skin and extending a short distance into the pulp. Unlike the bites of 



caterpillars, such as the tussock moth, these punc- 

 tures are not usually 2 healed with scar tissue, but 

 the uneaten flesh dries back a distance so forming 

 a circular dead spot, dark brown to black in color. 

 Often there is a dried exudate of whitish color 

 extending from the mouth of the punctures. This 

 exudate is evidently sap which has oozed from the 

 injured flesh and evaporated over a considerable 

 period of time. 



For a long time these injuries were not ascribed 

 to any specific insect, but rather thought to be due 

 to the work of small larvae of perhaps several species. 

 Among these the fruit-tree leaf roller (Archips 

 argyrotpila, Walker) was considered the most 

 responsible. 



The particular type of injury just described became 

 increasingly abundant in the Rodgers Bros', orchard, 

 and finally Mr. C. J. Rodgers observed a small case- 

 bearer larva which he believed to be the specific 

 cause of the injury. The following season (101G) 

 the writer made a study of the life history and habits 

 of this caterpillar. It was soon established that it was responsible for the particular 

 type of injury in question. It was also established that the presence of this insect 

 on the fruit was accidental, the principal food being the foliage. The feeding is done 

 between the two surfaces of the leaf in the same way that a true leaf miner does its 

 injury. The caterpillar is in reality a leaf-mining case bearer, moving about within 

 tie- protection of a case composed of leaf epidermis. This case appears to be enlarged 

 to accommodate the growth of the caterpillar by atldiug larger strips of epidermis. 

 The feeding larva' usually locate on the under surfaces of the leaves, but occasion- 

 ally on the fruit. The feeding habits are easily studied when the larva; are working 

 between the surfaces of leaves. After loosely attaching the edge of the case to the 

 leaf surface the larva eats through the epidermis and begins feeding on the cells 

 between the leaf skins. As the cells are removed the leaf skins become flexible to 

 an extent which admits more and more of the body of the insect between them. 

 In this way the lame enlarges the mine until it has to stretch full length from the 

 mouth of the case in order to feed. Very rarely the older larva? have been observed 



■Named i>>- J. N. Heinrieh of Bureau of Entomology, U. s. D. a., and description 



not yet published. 



The failure to heal is due to tin- fact that the punctures have been made at too late 



a date fur the &pp|< cells to divide and form lew tissue. However, if tilt; Very young 



trull Is attacked the punctures do heal with the formation of depressed regions or pits. 

 These pits vary from one-eighth to one-ciuailer inches in diameter and one-sixteenth 

 to one-eighth inches in depth. This form of injury is much less common than the 

 unhealed punctures. 



