10 



Natural Enemies. 



No parasitic enemies of the beetles, pupae, or larvae are recorded, but 

 Professor Webster, in Ohio, has bred from the eggs two species of small 

 h^mienopterous wasps, namely, Fidiohia Jlavipes Ashni., and Brachy- 

 sticha jidix Ashm., which he found to be doing most excellent work. 

 The former parasite was also bred from eggs by Slingerland in New 

 York State m 1905. Eggs are also attacked by two or three species 

 of small mites, which destroy them by extracting the contents. The 

 common little bro^^^l ant, Lasius hrunneus var. alienus, also has been 

 observed to feed upon the eggs, and several predaceous insects were 

 found by Dr. E. P. Felt in the course of his field work in New York 

 occurring in the soil infested by root-worms, and he thought it prob- 

 able that these preyed upon this species. The beetles are no doubt 

 fed upon by insectivorous birds and barnyard fowls, which also are 

 known to feed upon the pupae exposed in cultivating. 



Treatment. 



The insect may be fought in three important ways, namely, by 

 poisoning the adults with an arsenical spra}', jarring them from the 

 vines onto sheets, and destroying the pupae in the soil by cultivation. 



Poisoning. — Shortly after emergence the beetles begin to feed upon 

 the foliage, eating holes in the upper surface of the grape leaves, and 

 hence may be readily poisoned. The use of poisons was recom- 

 mended b}^ Mr. Marlatt" in 1895, while Messrs. Slingerland and 

 Johnson have shown by extensive practical experiments that the 

 numbers of the pest may be greatly reduced in this way, and that 

 poisoning in conjunction with cultivation, to be later mentioned, 

 affords almost complete protection from its injuries. To be effective, 

 however, the poisoned spray must be applied at the right times and 

 with great thoroughness. The beetles begin to put in an appearance 

 at about the close of the blooming period. Careful watch should be 

 kept, and upon the first signs of the chain-like feeding marks on the 

 leaves the vines should be thoroughly sprayed with a poison. A sec- 

 ond application should be made in a week or ten days. These appli- 

 cations are intended to poison the newly emerged beetles during their 

 first feeding and before they have deposited their eggs to any extent. 

 If applications be delayed two or three weeks beyond the time indi- 

 cated, a considerable percentage of the eggs will have been deposited, 

 and the treatments will lose much of their value. Vineyardists 

 having this pest to contend with should not make the mistake of 

 spra5'ing a little too late, but should have everything in readiness to 

 begin applications upon the first appearance of the beetles. The 

 beetles plainly avoid feeding on foliage sprayed with Bordeaux mixture 

 or arsenate of lead, seeking the unsprayed leaves as much as possible. 

 It is therefore especially necessary to make applications with great thor- 

 oughness, poisoning as nearly as possible the upper surface of everj^ 

 leaf, so that the beetles will be poisoned or forced to leave the vines 

 for food. This desired thoroughness of treatment is not obtained as a 

 rule by vineyardists, and greater care should be exercised in this work. 

 In commercial vineyards the tendency will be to hurry through the 



o Yearbook U. S. Dept. of Agriculture, 1895, p. 393. 

 284 



