The White Grub of the May Beetle. 13 



Professor Riley presents the following history, unaccompanied 

 with the authority or observations supporting it : " Soon after 

 pairing, the female beetle creeps into the earth, especially wherever 

 the soil is loose and rough, and after depositing her eggs, to the 

 number of forty or fifty, dies. These hatch in the course of a 

 month, and, the grubs, growing slowly, do not attain full size until 

 the early spring of the third year, when they construct f ff%. 

 an ovoid chamber, lined with a gelatinous fluid, change | ;'; 

 into the pupse [shown in the accompanying figure], and soon 

 after into beetles. These last are at first white, and all 

 the parts soft, as in the pupa, and they frequently remain 

 in the earth for weeks at a time, until thoroughly hard- 

 ened, and then, on some favorable night in May, they rise F 

 in swarms and fill the air. It is very probable that under pupa of the 

 favorable conditions some of the grubs become pupse, and 1 ay ~ eete ' 

 even beetles, the fall subsequent to their second spring ; but grow- 

 ing torpid on approach of winter,, remain in this state in the earth, 

 and do not quit it any sooner than those transformed in the spring. 

 On this hypothesis, their being occasionally turned up in the fresh 

 beetle state at fall ploughing, becomes intelligible " (First Report 

 Ins. Mo., p. 157). 



In all thus far written of the transformations of this insect, the 

 element of uncertainty largely prevails. It does not appear that 

 the larval life-duration has in a single instance been ascertained, and 

 many such determinations would be required in order to establish 

 a rule of uniformity or the range of variation. Observations 

 sufficiently reliable for use in building up a life-history are almost 

 wholly wanting. The following are of some value : 



In Clinton county, Missouri, the beetles swarmed late in May of 

 1866, from which eggs were doubtless deposited in June (the 

 female is said to live for about a week). The grubs [from these 

 eggs] were small, and not very injurious in 1867. They were 

 " full-grown, fine, fat fellows," in the autumn of 1868 (American 

 Entomologist, i, 1868, p. 37). From the above we educe : If the 

 larvae were then as reported, full-grown, the beetles from them would 

 appear in May of 1869, three years from their preceding appear- 

 ance. The grubs may have either transformed into pupae in the 

 autumn of 1868 or spring of 1869 — in the third year of their life. 

 Their larval period would then have been either two and one-third 

 or two and three-fourths years. 



