104 MASS. EXPERIMENT STATION BULLETIN 160. 



or scarcity of grasses. Rarely, however, is a large bog seriously hurt on 

 more than a few sections. The growers probably need not fear this 

 insect in 1915, for it rarely appears in great numbers two j^ears in suc- 

 cession, as its natural enemies soon control it. 



The g5"psy moth {Porthetria dispar L.) is becoming more of a menace 

 every year. Numerous reports of threatening danger from it were received 

 during the season of 1913, and this year it has caused no httle damage 

 on bogs in several localities. It is becoming more abundant yearly on 

 the uplands around the bogs in much of the cranberry section. The danger 

 to the bogs themselves, except possibly where water for reflowage is 

 abundant, evidently grows greater in proportion to this upland increase, 

 for while the female moths cannot fly onto the bogs to lay eggs the small 

 worms can readily be blown on by the winds. This insect, therefore, is 

 fast becoming a cranberry problem, and it must be given more attention 

 from now on. The following matters in connection with it need to be 

 determined especially: — 



1. In the more serious cases of bog infestation, does the trouble arise 

 from eggs laid on the bog the year before or from small caterpillars blown 

 on by the winds early in the season? 



2. Can gypsy moth eggs survive winter flooding, if the water is held 

 until late in May? It is known that they can endure an ordinary winter 

 flowage (until April 1). In case severe bog infestations usually arise from 

 eggs deposited the previous season, knowledge concerning the limit of 

 their ability to endure submergence becomes of prime importance. 



3. What is the best time to reflow to destroy this insect? The cater- 

 pillars are very hairy and will float for a long time before they die. The 

 larger they are the longer they can probably live in this way. For this 

 reason a bog should probably be flooded as soon after the eggs hatch, or 

 after the worms are found at work, as possible. The insect net which has 

 been recommended for discovering the fu"st stages of the false army worm 

 probably would be useful in detecting the presence of the small gypsy 

 moth caterpillars early in May. When a bog infested with this insect is 

 flooded, the worms usually float ashore alive in large numbers, and must 

 be killed by burning or by spraying with crude oil or kerosene. 



The cranberry weevil (Anthonomus suturalis Lee), which occasionally 

 harms a bog by working within the blossom buds and eating out their 

 hearts, thereby preventing blooming and fruiting, did much damage on 

 some bogs in Plymouth in 1913, and also caused some loss in the same 

 locality this year. Heretofore no effective treatment has been known for 

 this insect. Attempts to destroy it by flooding have been uniformlj^ un- 

 successful. The results of some spraying done this year under the super- 

 vision of Mr. Henry J. Thayer of Boston, in anticipation of injury from 

 this insect, are therefore interesting. Arsenicals ("Bordo Lead" with 

 Paris green) were used while the vines were in bud, some time before any 

 blossoms had opened. The bogs thus sprayed and adjacent unsprayed 

 vines were examined in August. The weevil evidently had done much less 

 damage where the spray had been applied. 



