568 NEW JERSEY AGRICULTURAL COLLEGE 



OBSERVATIONS ON THE INSECTS. 



It would be of little avail to gather statistics like the above without 

 carrying on at the same time a series of observations on the insect 

 to l)e affected. Opportunity for this was found at the Jamesburg bogs, 

 which have always suffered from the black-heads, and where vines 

 have been allowed to grow on the dams and on some ridges above the 

 water line. 



Ap7-il 19th. — Mr. Dickerson, when making his first temperature rec- 

 ords, made, also, a careful search for eggs of Eudemis, and found 

 quite a series of them, in good, plump condition, above the water line. 

 Some of these were brought to New Brunswick, where, after two or 

 three days' exposure to the dry air of the laboratory, they collapsed. 

 No trace of larva? was found at this date. 



April \3Sth. — A second examination was made and more eggs were 

 found — some in the same condition as before, more of them plump 

 and apparently ready to hatch, a few just hatched and boring into 

 the leaf tissue. The place where a larva had hatched and entered 

 was marked by a minute lump of frass or excrement, and when that 

 was removed a little chamber between the upper and under surface 

 of the leaf became obvious, sheltering a caterpillar hardly more than 

 a day or two old. Obviously conditions were favorable for a general 

 hatching, and April 23d was probably the earliest date at which any 

 larvfe appeared. Some specimens were brought to New Brunswick 

 for observation; other sprays containing eggs were tied into a mass 

 and submerged, so as to observe the effect of a water covering at that 

 stage of development. The specimens taken to the laboratory did not 

 remain within the leaf tissue, but began to eat the cells of the lower 

 side, forming characteristic, gnawed surfaces. 



May 1st. — The eggs above water had hatched generally, but there 

 was no sign of a leaf-folding anywhere. The casual observer would 

 ha.ve concluded that no larviie were yet present, while practically the 

 entire brood was out. The submerged plants were taken out, ex- 

 amined, and as no change was apparent in the eggs and no larva? had 

 hatched, they were replaced under four inches of water. It seems 

 certain that either the difference between air and water temperature 

 had checked development or that the physical effect of the covering 

 had produced that result. Additional material was brought to New 

 Brunswick and on May 3d one specimen molted; just ten days after 



