79 



the leaf ess state of the trees and the greater leisure which most fruit-growers have at 

 that season), vigorously prune and scrape the infested trees, and afterwards apply some 

 of the oily applications usually recommended. As a remedy not previously named, I 

 would mention linseed-oil, which has been used with marked and beneticial results. Many 

 persons have been deterred from using greasy or oily substances on their trees from a fear 

 of evil consequences resulting to the trees ; but there is nothing more certain than that 

 judiciously applied in early spring, after the sap begins to flow, these applications do not 

 injure trees, while they are effectual, more especially when applied at such season or 

 during thawing weather, in killing the eggs under the scales, the oily particles being 

 absorbed through and under the scales and destroying the eggs as soon as touched." 

 Crude petroleum T have kno%vn to be employed with excellent effect, but of course care 

 must be taken not to apply it to tender shoots or young branches. 



4. — The Gooseberry and Currant Sawfly — Nematm ribesii, Curtis. 



This is another very familiar pest on both sides of the Atlantic, and is only too well 

 known to gardeners, both here in and in England, from the havoc its caterpillars cause 

 -every year to the leaves of currant and gooseberry bushes. It has been fully described 

 in our Reports for 1871, 1874 and 1875, by Mr. Saunders. 



Fig. 47. Fig. 48. 



A leaf with eggs on the under side. Caterpillars of the Sawfly. 



The parent sawflies appear, in this country, about the end of April or beginning of 

 May, and lay their eggs on the under side of the leaves of the currant and gooseberry 

 almost immediately after they expand in the spring. The eggs are deposited in rows, 

 usually along the mid-rib and larger ribs or veins of the leaf, as shown in the figure 

 a.bove ; the female generally selects for the purpose leaves that are low down in the 

 middle of the bush. The larvae hatch out in about a week, and begin at once to feed by 

 eating small round holes in the softer parts of the leaf ; as many as sixty or seventy have 

 sometimes been found on a single leaf. The attack of the caterpillars may be discovered 

 at once by the appearance of a number of small holes eaten through the leaves. Each 

 brood feeds on the leaf on which it was hatched until it is completely stripped of all that 

 is eatable, and nothing but the hard ribs remain ; the individuals then scatter over the 

 bush, half a dozen or more being found on a single leaf, and in a bad attack soon com- 

 pletely denude the bush of its foliage. 



"These grubs," to quote Miss Ormerod, "are of a bluish-green, with black head, 

 feet, tail, and also black spots on each segment, and with a yellowish space just behind 



