10*» 



water parsnip (Sium lineare), s^oldeii rod (SoUdago nemoralis), fleabane (Erigeron tfanadense), 

 cat mint {Nepeta Cataria), common plantain, (Plantafjo major), Apocynimi androscemi folium. 

 None were eaten. When supplied with potato leaves, all ate freely.. This experiment was 

 repeated three times with unvarying results. 



The solancoous plants found in Ontario, outside of cultivation, on which it is generally 

 admitted Doryphora will feed are the Hyoscyrmiun nu/er, Physiilis viscnsa, Nirandra phi/sa- 

 loides, Solanum niyriim, Solanum dulcamara, Dahira stramonium. It is very doubtful if 

 Doryphora, either in the lavras or imago state, will feed on the last two named. They are, 

 however, all late plants, and would afford no food in the spring sea.son, and so scarce that 

 they would not feed the July brood for one hour. 



Experiment 4. — Aug. 8. Took in fifty mature D. 10 lineata larva;, forty-five of which 

 had changed to beetles on Aug. 26, while five had died in the pupating stage. The.se forty- 

 five beetles were kept without food ; four died on the fourth day, thirty -seven were dead on 

 the fifth day, thirty-nine on the eighth day, forty-two on the tenth day, forty-five on the 

 eleventh day. Over 75 per cent, died within five days, the males dying first. No pairing 

 took place, no ova were deposited, and no disposition to hybernate was evinced.. This is the 

 average of three cases conducted simultaneously, and which varied but little. 



Experiment .5. — Aug. 8. Took in thirty mature beetles all of which had partaken of 

 food, and kept them without food. Two were dead in fourteen days ; eight in nineteen days ; 

 thirteen in twenty-three days ; sixteen in twenty-seven days ; twenty-four in forty-seven 

 days. Twenty per cent, survived forty-seven days' fasting ; pairing occurred, and ova were 

 deposited to a small extent during the first ten days. This is the averi^^e of three cases con- 

 ducted simultaneously. 



There is a very marked ditl'erence between this result and that of Experiment 4, where 

 the beetles had never partaken of food. 



E.xperiment 6. — Aug. 15. Twenty pairs Doryphora, after being well fed were kept in 

 a dry situation ; thirty two were dead in twelve days ; all dead in twenty-two days : the males 

 died first ; a few ova were depo.sited during the first week. This experiment was repeated 

 three times. 



E.xperiment 7. — As to the rate of feeding, five experiments were tried. The beetles 

 numbered fourteen to twenty -one, and the times from ?,\ to 168 hours ; the average of the 

 five trials was, one beetle will eat one square inch of potato leaves in thirty hours ; the max- 

 imum rate was ten hours, minimum was thirty-seven hours. It may be stated that one beetle 

 during its imago life will defoliate one plant of potatoes. 



Experiment 8. — Aug. 20. Took in fifty beetles which had been well fed ; eleven imme- 

 diately buried themselves in the sand. September 6. All dead above ground ; turned out 

 the sand and found the eleven alive ; replaced sand, also beetles ; eight at once buried them- 

 selves. September 1,5. Three remaining on surface dead. September 20. Found all on 

 surface of sand, which I found quite dry ; on wetting .sand all went down, are now alive Octo- 

 ber 16. 



Experiment 9. — September 1. Took 100 Doryphora larvaj, some immature, fed them 

 on potato. Sept. 10, all pupating. Sept. 20, 15 beetles out. Oct. 1, beetles all dead. On 

 turning out the sand found that none had hybernated. This agrees with the results of seven 

 experiments, and shows that there was no disposition to hybernate until after the middle of 

 August, and then only by beetles which had fed. 



The date of hybernation will vary according as the season is warm or cold, but I think 

 it pretty certain that beetles which have not fed will not survive the winter. 



A result of experiment 4Vas the finding of a pupa case of Liplella doryphora under 

 conditions which were fully narrated to you at our September meeting, and which you all 

 agreed were conclu.sive as to the advent of this farmers's friend in Toronto. 



It is hoped the publication of this will elicit evidence of its occurrence in other counties 

 in Ontario, liut it must be borne in mind that the very general use of Paris green by potato 

 growers, has hitherto prevented the increase of this as well as other natural enemies of D. 10 

 lineata ; has, in fact, rendered their existence almost impossible. 



