85 



cover and destroy all of the newly hatched and not very conspicuous 

 Adalia larvae on the leaves and twigs. The tree was badly infested 

 with plant lice, and these furnished so much food for the Adalia larvse 

 that very little damage was done to the Chilocorus; but that the former 

 would eat the latter was proved by observation in a few instances, and 

 by inclosing them together in a jar; the smaller larvai of Chilocorus, 

 our native species, Uvuhietii^, being used for the experiment, were 

 eaten, but nearly grown larvae— big spiny fellows— were let alone. 



The greatest menace to the safety of the Chilocorus larvee is the 

 wheel bug. It was comparatively easy to keep the outdoor cages free 

 from this predaceous bug, but had no steps been taken to destroy the 

 wheel bugs in the grove the success of the introduction of the Chilo- 

 corus would have been very much jeopardized when the time came for 

 their general liberation. These wheel bugs were observed feeding on 

 the larvae of Adalia and on the larvffi of Chilocorus. They did not 

 feed on the scale insects, the latter being much too small for their 

 notice, and it may be that the almost complete absence of our native 

 Chilocorus in this grove is due to the very great abundance of the 

 wheel bug. When our fears relative to the wheel bug were fully 

 aroused, Mr. Kotinsky, of the Entomological Office, spent a day going 

 through this little grove, destroying egg masses and killing the wheel 

 bugs that had already hatched. He estimated that he killed 9,000 -wheel 

 bugs in this grove of not less than one-eighth of an acre, and subse- 

 quent results indicated that even with that number destroyed a good 

 many had escaped, and several later inspections had to be made to 

 fairly free the trees. This wheel bug has become extraordinarily 

 abundant in the vicinity of Washington in the last few years, and has 

 been increasing in numbers very considerably in its northern range, 

 which has already been pushed as far as New York and New England. 



All the egg masses of our native Mantis that could be found were 

 collected and destroyed. Hatching, however, had already begun. 

 The Qgg masses of the European Mantis were taken indoors and kept 

 inclosed, and those that had not already hatched were allowed to come 

 out and devour each other until the final extermination was effected 

 by this natural means. The hatched and escaped mantides are with 

 difficulty detected; they are of a dull grayish color, harmonizing with 

 the bark and leaves, and their quick movements and their habit of 

 keeping out of sight under leaves or running around to the other side 

 of twigs when approached render their discovery difficult. All that 

 were found in the grove, however, were desti'oyed. 



Of the five insects mentioned above, four are dangerous enemies of 

 the larvae of the scale-feeding ladybirds; and, in proportion to their 

 numbers, the benefits from such ladybirds will be decreased." 



''A single instance was noted by Mr. Kotinsky, in late July, of the feeding of a 

 larva of a Telephorus on a Chilocorus larva. 



