104 STATE BOARD OF AGRICULTURE. 



This treatment if properly given is entirely effectual, and besides being 

 cheap and rapidly jjerformed, has the additional merit of being safe to 

 use on the trees. The principal drawback to its use is that the gas 

 diffuses rather slowly, and when the work is done in a large room we have 

 made the requirement that no trees be more than ten feet from the fum- 

 igating pan, and in order that an even distribution of the gas be secured, 

 have required that the trees be exposed to the gas for one hour, instead 

 of thirty minutes as formerly. Careful experiments have shown that 

 when the trees are fairly well ripened there is no danger, whatever, when 

 trees are fumigated for this length of time, using one ounce of cyanide 

 of potassium for 100 cubic feet of space. In fact, this is the strength 

 used in California for fumigating growing orange trees. 



During the spring months many of the larger nurseries were visited 

 to make sure that the stock carried over and the surroundings were in 

 a satisfactory condition. Careful watch was also kept of the stock 

 as it was packed for shipment, and frequent examinations were made of 

 the trees purchased by them, and esi)ecia!ly of those brought in from 

 other states. 



INVASION OF BROWN-TAIL MOTHS. 



Early in January the New York Department of Agriculture reported 

 that its inspectors had found winter nests of the brown-tail moth con- 

 taining living larvae upon nursery seedlings imported from Angers, and 

 other points in France. 



This insect has periodically caused immense losses in Germany and 

 other European countries and has been in Massachusetts for some twelve 

 or fifteen years and in that time has spread throughout New England, 

 it having been found at the extreme northeast corner of Maine. 



While it is most commonly found on fruit trees, being particularly 

 fond of the foliage of the pear, it also attacks many of the forest trees, 

 so that the injury it might cause, if it should secure a foot-hold in Michi- 

 gan, would be wide-spread. 



Though its ravages can be checked in various ways, it would be at a 

 considerable expense, and especially for the forests it would be pro- 

 hibitive. Every precaution should therefore be taken to prevent, or at 

 least to delay the introduction of this pest into Michigan orchards as long 

 as possible. And in order that its spread may be checked, if it once ob- 

 tains a foot-hold, every one should be informed regarding its appearance, 

 life history, and methods of combating it. 



DESCRIPTION OP BROWN-TAIL MOTH. 



The moth itself is pure white in color, except for a thick tuft of yel- 

 lowish brown hairs at the tip of the abdomen. It has a wing-spread 

 of 2y^ inches and is a strong flyer. The moths appear in July and de- 

 posit eggs upon the underside of the leaves, in rather long, slender 

 clusters of a golden-brown color. 



The eggs hatch in August and the caterpillars, which reach a length 

 of two inches, are bright orange in color with a broken row of white 

 spots on either side of the back. The caterpillars also have two bright 

 red spots on the back towards the rear end. While quite small they 

 draw the leaves together and spin a silky web about them, making a sort 



