22 N. H. Agr. Experiment Station [Bulletin 313 



handicapped by loss of equipment by fire, tests were made on a 

 water-heating pail, a brooder assembly, several electric fence con- 

 trollers and other devices. (Bankhead-Jones Offset Fund) 



Contact Insecticides 



In their study of contact insecticides, W. C. O'Kane, J. G. Conklin, 

 L. C. Glover and Robert L. Blickle are investigating the rate of pene- 

 tration of oils through insect integument. Now that a satisfactory 

 technique has been developed, good progress has been made. A series 

 of studies have been completed using a low-boiling and a medium- 

 boiling fraction of petroleum oil, as compared with corn oil, a typical 

 glyceride. Results show that penetration by the low-boiling fraction 

 is rapid ; by the medium-boiling fraction penetration is slow, and 

 with the glyceride it is negligible. 



Studies with various alcohols indicate that methyl gives the most 

 rapid penetration, followed by ethyl and octyl and then by isopropyl 

 and butyl. Materials still under study include pine oil, mesityl oxide, 

 butyl ether, ethylene dichloride, ethyl acetate and dichlor ethyl 

 ether. All these materials were selected because of their use or pos- 

 sible use as constituents of contact insecticides. (PioncIJ Fimd) 



Ovicides 



The initial rate of penetration of various glycerides, terpenes and 

 hydrocarbon oils has been determined for the eggs of several species 

 of insects; namely, American roach, Mexican bean beetle, Colorado 

 potato beetle and the larger milkweed bug. The oils enter the egg of 

 the American roach more easily than those of the other species, 

 while the eggs of the Mexican bean beetle are the most impervious. 

 Increase in temperature increases the rate of entrance. (Adams 

 Fund) 



Apple Maggot 



A late frost in the spring of 1938 which completely destroyed the 

 set of fruit at the Marden Orchards in southern New Hampshire 

 where the project was being carried on has interrupted this experi- 

 mental program. Plowever, the complete failure of fruit in this 

 locality provides an opportunity for certain studies of survival 

 and of dispersion of the species under investigation. (Hatch Fund) 



Insect Record during the Year 



A severe outbreak of the army worm occurred in June, 1938, when 

 several fields of growing crops were stripped in southern and central 

 New Hampshire. The department was active in studying the situa- 

 tion and recommending defense measures. 



The European corn borer became markedly a])ui]dant in various 

 areas in southern New Hampshire; but the situation in northern 

 New Hampshire, where the species is not yet widely prevalent, has 

 remained practically unchanged. 



The department has been active in a survey conducted to deter- 

 mine the extent of infestation by the European spruce sawlly, which 

 has been found in a number of new localities and in some has 

 increased in intensity. Preparations are underway for the rearing 

 of a cocoon parasite of the sawlly for liljeratioii during the summer 

 of 1939. Approximately 140,000 cocoons are on hand, and it is hoped 

 to rear over a million and a half parasites this year. (Hatch Fund) 



