THIRTEENTH ANNUAL YEAR BOOK— PART XIl 711 



When the adult grasshoppers are present in large numbers the "Hopper 

 Dozer" can often be used to advantage. This consists merely of a pan 

 or tank filled with water on the surface of which is a thin coat of kero- 

 sene. Mounted on two or three runners high enough that the bottom 

 of the pan scrapes the alfalfa the pan or tank can be driven back and 

 forth over the field, and as the alfalfa is disturbed, the grasshoppers 

 jump blindly against the high back of the pan and drop into the water 

 where they are killed immediately. 



Blister Beetle. — The blister beetle has occasionally appeared in such 

 numbers as seriously to damage large areas of alfalfa. During one stage 

 of their development they live almost altogether on grasshopper eggs. 

 Therefore any practice which will reduce the number of grasshopper 

 eggs will largely control the blister beetle. They are especially liable to 

 be numerous enough to cause damage in seasons following those years in 

 which large numbers of grasshoppers have been in evidence. 



It is of interest to note that the possible damage of each of the two 

 most troublesome alfalfa insects is very largely controlled by the other. 



The blister beetles were especially abundant in most sections of the 

 state in 1912 and caused considerable damage on many fields. 



Web Worm. — In some of the older alfalfa growing states on the west- 

 ern border of the Mississippi valley, the web worm has occasionally 

 caused serious damage. Eggs are laid on the alfalfa plant and soon 

 hatch ifito small green caterpillars with black spots scattered over the 

 back. These worms make masses of webs, at the same time living on 

 the alfalfa plant. They do most of their damage during the months of 

 June, July and August. As these mature they enter the ground, later 

 coming out as moths which lay the eggs for the July brood. The July 

 brood, in turn, produces an August brood which lives over winter in 

 cocoon form, in the soil. When they are present in considerable num- 

 bers the hay had better be cut, thus eliminating the later brood which 

 might develop, by removing the worms before they go into the soil. A 

 thorough disking of the field in the spring will also greatly reduce 

 their number. 



Some fields have been seriously damaged by this insect in Iowa. 



Pocket Gopher. — Perfect stands of alfalfa have been practically ruined 

 through the ravages of the common pocket gopher. This little animal, 

 burrowing through the soil, throws up large piles of dirt which not 

 only bury many of the plants but also make it quite impossible to sat- 

 isfactorily cut the crop. 



While these pests can be greatly reduced by shooting and trapping a 

 better method of accomplishing this is by the use of poison. 



Small pieces of poisoned apple or potato dropped in the runways will 

 usually be found effective as destructive agents since the pocket gopher 

 lives almost altogether upon succulent green vegetable matter. 



ALFALFA TROUBLES. 



After carefully studying the successes and methods of others in han- 

 dling alfalfa, and after taking every known precaution to insure the sue- 



