388 BOARD OF AGRICULTURE. [Pub. Doc. 



the center, is circular in outline, and is white or light gray in color, 

 sometimes with its central elevation orange-yellow. It lays eggs from 

 which adult scales are produced in about two and a half months, but 

 the different generations run into one another, so that almost all 

 stages may be found at any time. 



Morgan's Scale. (Chrysomphalus dictyospermi Morg.) 

 This important pest on palms is circular in outline, dark colored, 

 usually with an orange spot near the center, and is quite flat, pro- 

 jecting only very slightly from the leaf. The young are born alive, 

 and males are unknown. There are several generations in a year, 

 but, as was stated for the white scale, these run into each other or 

 overlap. 



Mealy Bugs. 



Two kinds of mealy bug are met with in greenhouses, the more 

 common one having a fringe of spines around the body, the two at 

 the hinder end being somewhat longer than the others. In the less 

 common kind these hinder spines are much longer, — sometimes as 

 long as the body. In both the body is more or less covered with a 

 white, waxy substance, which has been the cause of their receiving 

 the name "mealy bugs." 



The several hundred eggs laid by the female are carried under the 

 hinder end of the body, and as these are laid the insect tips upward 

 till it is almost standing on its head. When egg laying has been 

 completed the parent dies, and after about two weeks' time from the 

 laying of the first eggs these hatch. The newly hatched young are 

 quite small, not covered with the wax, and after a time they move about 

 and begin feeding, which continues for six or eight weeks before they 

 become adult, sucking the juices from the plants they are on. 



Mealy bugs feed on many plants, but perhaps the oleander, coleus, 

 some palms and citrus plants are preferred members of the list. 



Methods of Control. 

 The widely differing life histories and habits of the various insects 

 found in greenhouses prevent the use of any single method for their 

 control. The treatment in each case must depend upon the kind of 

 insect to be treated, and in many cases as well upon the kind of plant 

 it is on. For some plants the cultural methods necessary to obtain 

 the best results are those most favorable to the increase of their insect 

 pests, while with others a treatment strong enough to destroy all the 

 pests would certainly destroy or at least seriously injure the plants. 



Preventive Measures. 

 It is almost needless to state that an empty greenhouse should have 

 no pests present, and this will be the case if the house has been thor- 

 oughly cleared out and then fumigated, directions for which are given 

 below. 



