38 MASS. EXPERIMENT STATION BULLETIN 388 



Quite a number of bogs were reflowed from mid-May to mid-July, 1941, to 

 check severe infestations of the root grub. This treatment was generally fairly 

 successful, as it usually has been heretofore, but it was found that in several 

 cases some grubs survived. 



Cranberry Fruit Worm {Mineola vaccinii). Arsenate of lead, 8 pounds in 100 

 gallons of water with a casein spreader, applied at the rate of 400 gallons per acre 

 at the times when derris and cryolite are most effective, controlled this insect 

 very well on experimental plots, but less completely than derris or cryolite. 

 Xanthone, both in a spray and in a dust, failed to affect it appreciably. 



Gypsy Moth {Porthetria dispar). Cryolite, 14 pounds in 100 gallons of water, 

 400 gallons an acre, failed to cause much reduction in the number of maturing 

 caterpillars on a bog, as did also dusting with 100 pounds of natural cryolite 

 per acre. 



Cranberry Girdler {Crambtis hortuellus). Fifty pounds of 4 percent rotenone 

 derris dust (without activator) to an acre killed nearly all the moths of this pest 

 on a treated area, but was not quite so effective as pyrethrum. 



Black-headed Fireworm (Rhopobota). An interesting development was the 

 use of a mixture of cryolite and impregnated pyrethrum dust. Treatments with 

 this mixture cost no more than those with clear pyrethrum dust and seemed to 

 have greater value, especially with the first brood. The cryolite provides a con- 

 siderable control after the pyrethrum ceases to act and so takes care of most of 

 the young worms as the eggs continue to hatch. 



Prevalence of Cranberry Pests. The relative general abundance cf insect pests 

 on Massachusetts bogs in the 1941 season was as follows: 



1. Gypsy moth more abundant and destructive in Plymouth County than for 

 many years, but much reduced on the middle and outer Cape, not giving much 

 trouble there. 



2. Blunt-nosed leafhopper {Ophiola) reduced as in recent years, because of 

 general treatment. 



3. Cranberry fruit worm only moderately troublesome and through working 

 early; much less prevalent than in 1940, less eggs being laid by the moths, and the 

 eggs being attacked by the Trichogramma parasite more severely and generally 

 than usual. 



4. Black-headed fireworm less abundant than usual and less than in 1940. 



5. Firebeetle (Cryptocephalus) generally very scarce, but abundant on lOacres 

 of a bog in Norton. 



6. Spanworms about the same as in 1940. 



7. False armyworm {Xylena) even more prevalent than in 1940; more trouble- 

 some than for many years. Blossom worm even less prevalent than in 1940. 



8. Cranberry girdler more harmful than in 1940. 



9. Cranberry weevil about as in 1940. 



10. Cranberry spittle insect {Clastoptera) and tipworm (Dasyneura) rather 

 more troublesome than in 1940. 



11. Spotted fireworms (Cacoecia) very few. 



Control of Cranberry Bog Weeds. (Chester E. Cross.) Paradichlorobenzene, 

 naphthalene, ferric sulfate, ferrous sulfate, copper sulfate, borax, kerosene, and 

 a special petroleum oil, PD-428D, were tried on various kinds of bog weeds, 

 276 plots being treated. The results of many experiments have shown that many 

 cranberry weeds can be killed in May and early June by treatments largely in- 

 effective later in the season. 



