38 N. S. ENTOMOLOGICAL SOCIETY 



NOTES ON THE LIFE HISTORY AND IMMATURE 

 STAGES OF THREE COMMON CHRYSOMELIDS. 



W. E. Whitehead. 



Disonycha 5 — vittata Say. 



During April, 1917, a number of eggs of this beetle were 

 found by Mr. C.B. Gooderham, and an effort was made to work 

 out the life history, but owing to the difficulty in discovering 

 the host plant, most of the larvae died. Eventually it was 

 found that they were feeding on a species of Golden Rod (Soli- 

 dago squarrosa), and during the past season the following 

 study was made upon this host. 



Summary of Life History. 



The eggs are laid during April and May,but any that have 

 been kept under observation have not hatched until early in 

 June, the duration of this stage being from a few weeks to two 

 months. The larvae feed exclusively on Golden Rod. They 

 were placed on a number of other weeds but refused to feed 

 at all. Those that were kept in the laboratory only moulted 

 twice and the length of the larval period varied from 50 to 55 

 days. The larva upon reaching maturity enters the ground, 

 forms an earthen cell and pupates, the pupal period lasting 

 from 34 to 40 days. The adult upon emerging feeds upon its 

 host plant for several weeks and then hibernates. The exact 

 length of this stage has not been determined, although a fairly 

 accurate estimate may be arrived at. The length of time spent in 

 the different stages will be found in the accompanying table. 



The Egg. 



The eggs are deposited in masses varying from five to 

 forty and are attached at the base to rotten stumps and wind- 

 falls on grown up pasture land that was once woods. Many 

 of them are inserted in crevices and under the loose bark. 



Description: — Cylindrical, widest one third of total length 

 from posterior extremity which is broadly rounded, tapering 

 gradually towards apex. Chorion, distinctly sculptured by 

 fine radiating ridges. 



