.58 MASS. EXPERIMENT STATION BULLETIN 355 



down the trunk to the bands or crawled up from the ground. All but one of these 

 trees were blown over, the trunks split open, and the bands reduced to fragments. 

 On the one tree where the bands were intact, 54 larvae were collected in the 

 upper band and 32 in the lower. 



Introduction of Parasites of Oriental Fruit Moth in Peach Orchards. (A. I. 



Bourne.) In 1938 the work of rearing parasites of the oriental fruit moth was 

 conducted in the entomological laboratories at Amherst. By agreement with 

 the Entomology Department of the Connecticut Experiment Station, the services 

 of Mr. A. DeCaprio were secured from June 1 to July 15. Mr. DeCaprio was in 

 direct charge of the collection of breeding material in New Jersey, its shipment 

 to Amherst, and later the distribution of parasites in the peach orchards. The 

 facilities of the laboratory proved very satisfactory for the proper care and hand- 

 ling of the breeding material, and there was sufficient emergence to fill the original 

 orders for 16,000 parasites. Because of low mortality in the breeding material 

 and a higher degree of parasitism than anticipated, it was possible to fill late 

 requests for colonies and leave a small surplus of parasites which were liberated 

 at the discretion of the county agents. In all, more than 20,000 parasites, Mac- 

 rocentrus ancylivorus, were liberated in late June and early July, in 58 orchards 

 in 9 counties of the State. 



The rainfall in July, as recorded at the college, was nearly twice the normal 

 for that month, and some parts of the State e.xperienced even heavier precipita- 

 tion. The frequent showers, with intervening periods of high temperature and hum- 

 idity, proved almost ideal for the development of the oriental fruit moth, and 

 at the same time constituted the worst possible conditions for the activities of 

 the parasites, so that on the whole the Macrocentrus parasites released in Massa- 

 chusetts peach orchards in 1938 proved less effective than in any year in which 

 liberations have been made. While early twig infestation by the fruit moth larvae 

 was not extensive, late season damage to fruit was severe in many orchards. 

 Similar weather conditions prevailed over much of Connecticut where results 

 with the parasites corresponded with those in Massachusetts. In New York and 

 Ohio, however, the prevailing weather was more nearly normal as regards tem- 

 perature and humidity, and the results with Macrocentrus and similar parasites 

 "were very satisfactory, indicating that under normal midsummer conditions 

 favorable results can be expected from the parasites liberated in the orchard. 

 Even under the adverse weather conditions prevailing in Massachusetts during 

 the season of 1938, the few growers who purchased a sufficient supply of parasites 

 to allow the ratio of 1 colony to approximately 300 trees reported the fruit at 

 harvest to be relatively free from fruit moth damage. 



Control of Cabbage Maggot. (W. D. Whitcomb, Waltham.) Eggs of the 

 cabbage maggot were first found in the field on April 29. This is about a week 

 earlier than the first oviposition in other years, because of the unseasonably warm 

 weather in late April. 



Cabbage maggots were normally destructive. The abundant and well-dis- 

 tributed rainfall in May and June stimulated the growth of secondary roots on 

 infested plants so that the majority of them produced marketable heads. Under 

 these conditions only 4 percent of the untreated plants in the experimental field 

 were killed, although 76 percent of them showed moderate or severe injury to 

 the roots by the maggot. Furthermore, 62 percent of them produced marketable 

 heads, which was the best yield from untreated plants in several years. 



Nevertheless, control treatments were effective and worth while. Corrosive 

 sublimate solution (1 ounce in 10 gallons of water) gave 97 percent protection 

 when applied once and 100 percent protection when applied twice and produced 



