THE DOCK FALSE-WORM. 35 



On August 12 a chrysopid (lace wing) larva was discovered in the 

 act of devouring one of the false-worms on a plant at the laboratory. 

 The worm was small, having passed its first molt the day before. 

 On August 26 another chrysopid larva was found eating a worm 

 that had hatched August 24. It is probable that ladybird larvae 

 sometimes also feed upon immature false-worms. 



REMEDIAL MEASURES. 



Remedial measures may become necessary for the control of the 

 dock false-worm where its food plants are abundant. Thorough 

 and frequent cultivation will keep the plants from growing in orchards 

 where clean cultivation is practiced. The bindweed {Polygonum 

 convolvulus) , sometimes called black bindweed, is ordinarily classed 

 as a noxious weed, and the other plants are often troublesome 

 and should be kept out of an orchard, even when the false-worm is 

 not present. However, this is not always possible in orchards kept 

 in sod, or where a perennial cover crop, such as alfalfa, is grown. 

 With this in mind, in the fall of 1915 the writer performed a number 

 of experiments in banding trees and in cleaning out the growth of 

 weeds about them, to determine the best method of preventing the 

 full-grown worms from climbing up and getting at the fruit. This 

 work was done in the orchard from which the overwintering larvae 

 were collected in the spring. It is situated in the Entiat Valley, 20 

 miles north of Wenatchee, Wash. A portion of the orchard was 

 selected where there was an average infestation of worms on the 

 bindweed. The latter was growing up into the trees in many places, 

 clinging to the trunks and lower limbs. The orchard consisted of 

 Esopus (Spitz enburg) trees, alternating with Jonathans. Only the 

 latter were used, since the } r ear before it was noted that the Jona- 

 thans were injured more than the others. Sixteen trees were used, 

 divided into four plats of four trees each. In Plats A, B, and 

 C, the bindweed and alfalfa were cut off near the ground under the 

 trees, and some of the lowest branches were clipped off, leaving no 

 way for the larva to get into the tree except by way of the trunk. 

 A band of a commercial sticky substance, one-eighth inch thick 

 and 3 inches wide, was then applied to the trunks of the trees in 

 Plat A, just below the point where the main limbs branched out. In 

 Plat B, an 8-inch strip of cotton batting was placed about the trunk 

 of each tree and tied on with cord about the middle. The upper half 

 of the cotton band was then rolled down over the cord. Plat C re- 

 ceived no treatment aside from clearing out the weeds and clipping 

 a few branches. Plat D was used as a check and was left untouched. 

 This work was done on August 26, as many of the larvae were found 

 to be approaching maturity. The fruit was picked October 5, and 

 during the interval other work prevented the writer from visiting 



