76 



The Streaked Cottonwood beetle ( Plagiodera scripta) appeared in our 

 grounds during June on a young Populus, which it threatened to com- 

 pletely defoliate. The tree being small admitted of thorough drenching 

 with a plant syringe with the solution of arsenic and ammonia — 1 ounce 

 of arsenic in 1 quart of aqua ammonia — 1 tablespoonful of the solution 

 to a gallon of water, by which means and a little hand-picking the pest 

 was so thoroughly exterminated that it did not reappear later in the 

 season. 



The 12-spotted Diabrotica (D. 12-punctata) was a serious pest during 

 the latter part of the season, not only on squash and cucumber vines, 

 but on late sweet-corn, and especially in its injuries in the flower garden 

 on the blossoms of roses, dahlias, and cosmos on which it literally 

 swarmed. To save the flowers it was necessary to make the rounds two 

 or three times a day and capture or put the beetles to flight. They 

 were not much affected by any of the milder insecticides, and the arseni- 

 cal remedies could not very conveniently be applied. 



The European Cabbage-butterfly (Pieris rapce) acquires one or more 

 new food plants annually and threatens to become quite omnivorous. 

 This year it proved in several localities very destructive to nasturtiums 

 (Tropceolum) both in flower and vegetable gardens. None of its para- 

 sites have yet appeared, so far as I have been able to ascertain. It 

 seems to have entirely supplanted our native P.protodice in this locality. 

 Wishing to obtain some larvre of the latter for a certain purpose, I made 

 many examinations during the summer of the neighboring cabbage 

 plantations, but did not succeed in finding a single one. 



SPECIAL STUDIES. 



The Spinach Beetle. 



(Disonycha collaris Fabr.) 



About the middle of April I observed the leaves of spinach in the gar- 

 den were badly perforated, and, upon examination, I found on the un- 

 der surfaces numbers of small, dingy, white larvre, evidently of some 

 Chrysomelid beetle. They reposed in the numerous depressions between 

 the veins, and a slight shake or jar caused them to drop to the ground. 

 The insects increased in size and numbers until by the middle of May 

 all the leaves were badly injured and the gardeners hereabout com- 

 plained that their spinach was so u worm eaten" this year that they 

 could no longer offer it for sale. A few of the sarnelarvre were also found 

 on young beet leaves, especially of the white and yellow varieties, and 

 upon the wild Chenopodium album, the latter being, I suspect, the orig- 

 inal food plant of the insect. 



As the larvas drop so quickly upon being disturbed, it is not often 

 that they are observed by the gardener or cook, and the damage was 

 attributed by many to "some kind of cut-worm." By plucking the 



