CAPE COD CRANBERRY INSECTS 53 



3. By ihe Worms fdlliiu/ an the Bo<j Mart/in from (>vcrli<iii(i;ini Trees. — 

 Tlie iijilands around most boji's now are cleared of trees and brush well hack 

 from the margin, so the chances of this generally are small. 



4. By ihe Caterpilhns criticliin/ across (he Mar</in(il Dilch in their later 

 Sta(/es. — When the surrounding upland is heavily infested, coni])lete defolia- 

 tion of the trees commonly occurs, and then the hungry v.oruis often crawl 

 onto the liog. 



Treatment. 

 This pest is controlled readily on cranlierry hogs liy: 



1. HoiJing the ivinter poml iill May ,.'.7. — This kills the eggs laid on the 

 bog the year before and usually catches most of the wind drift. See page 11. 



2. Reffoodiny about May J9 for 36 hours. — The wind drift is generally 

 about over then, and the water kills the worms before they do nuich harm 

 unless they are very numerous. A fourteen-hour flood kills then) after they 

 are a third grown, but if they are abimdant treatment .•-hould not be delayed 

 after the above date most years. The date for the earliest springs is May 24 

 and for the latest June 3. Many of the small worms cling to the vines as the 

 water rises and never come to the surface. As they grow they lose this habit. 

 This may explain their greater resistance to drowning in their first stages. 

 The larger worms thrash themselves to death on the surface of the water. 



Late May is also the time to flood to control rose-bloom. If the water is 

 held 36 hours the swollen ])ink shoots (Plate Two, fig. 6) caused by the dis- 

 ease collai)se and dry up a (h.y or two later. 



This flooding also destroys other pests that may be at work, such as false 

 annyworms, blossom worms, black-headed tireworms and green sjianworms. 



3. Sprayiny xvith 6 pmnids of dry lead arsenate in Jtm yallons of icater 

 about May 22. — The date should be about May 16 in \ery early springs and 

 about May 28 in \ery late ones. This is very effecti\e when the worms are 

 small. They are hard to kill with arsenicals after they get large. 



4. T>ustin(/ heavily ici^h one jiari of sodinm fJuosilicate mi.ved icith four 

 parts, by vohime, of hydrated lime. — This is the only insecticide so far tried 

 which kills the mature worms without reducing the crop much. 



5. Keeping the maturing icorms from rraxcling onto the I>og. — This is best 

 done by: 



(a) Removing the trees, especially the oaks, and the brush for 1.50 feet 

 from the bog nuirgin. This also helps to prevent frosts somewhat by allow- 

 ing freer air movements across the bog at night. 



(b) Spraying the brush and trees for 200 feet from the bog margin with 

 lead arsenate when the worms are small. This always is advisable if the 

 upland has not been cleared and is thickly infested. 



(c) Keeping the marginal ditch cleaned out and partly full of water, with 

 a film of kerosene or fuel oil on the water, during the worm-crawl. Some- 

 times the ditch must he deepened considerably for this. 



(d) Spraying the upland bordering the bog with fuel oil. This should be 

 done only when the wonu-crawl is thick and other measures have been neglect- 

 ed or are impracticable. It may have to be repeated several times unless the 

 strip sprayed is wide. Short lengths of old hose should be used for this, for 

 oil soon ruins hose. 



