226 OHIO EXPERIMENT STATION: BULLETIN 332 



in addition to the females, many winged males also are captured as 

 they are attracted to the females and attempt to copulate, the 

 bridging of the band becomes a comparatively easy matter. It will 

 be seen from the foregoing that if the banding method is relied 

 upon, the bands must be placed in position in good season and must 

 be inspected at frequent intervals to maintain a sticky surface. 

 Particular attention should be paid them during the period when 

 the spring brood is most likely to emerge in quantity to prevent the 

 bands from becoming bridged. 



Nevertheless if by careful attention the banding method can be 

 made to serve the purpose intended, it is the cheapest form of pro- 

 tection, particularly in the case of large trees which are difficult 

 and expensive to spray. 



The second method of control, as opposed to banding, is spray- 

 ing with poisons. The application should be made when the canker- 

 worm larvae are very small. A good rule to follow is to spray when 

 the leaves are about an inch long. Arsenate of lead, used at the 

 strength of 5 or 6 pounds of paste or an equivalent amount of pow- 

 der to 50 gallons of water, is satisfactory, but particular emphasis 

 should be placed on spraying the tops of the trees, since at this 

 point cankerworms work their greatest havoc. 



Where trees, whether fruit or shade, are annually sprayed with 

 poisons soon after the leaves appear, the cankerworm pest is neg- 

 ligible. 



THE BLACK WALNT7T DATANA 

 (Datana integcrrinia G. & R.) 



At its present rate of destructiveness the walnut datana bids 

 fair to eliminate black walnut from our list of native Ohio trees. 

 Thousands of trees are dying annually from its work. It is there- 

 fore of sufficient importance to merit careful attention. 



Description. — This insect is rarely seen except in the larval 

 stage, when it is most frequently noted as clusters of caterpillars 

 feeding on the foliage chiefly of black walnut. When first hatched, 

 the larvae have black heads and brick-red bodies, the latter bearing 

 faint stripes. As the larva ages, the brick-red coloration deepens 

 and the Hues become more distinct; long, sparse hairs appear, and 

 in the final, or full-grown larval stage, the body is black, very indis- 

 tinctly lined and generously adorned with a growth of long white 

 or dirty gray, frowzy hair. The full-grown, well-fed caterpillar 

 measures a little more than 2 inches in length. (See Plate XXIX, 

 Fig. 5.) 



