28 THE MONTHLY BULLETIN. 



There are two Avonderful little true flies or Diptcra, of the genus 

 Diplosis, which do great work against the guava and Hibiscus mealy- 

 bugs in the Philippines. These, during the maggot state, feed upon 

 the eggs and young of their hosts. The two species have quite different 

 habits. The larva of one has the peculiar faculty of being able to jump 

 ^"or a considerable distance when disturbed. The purpose of this jump- 

 ing is evidently to assist the larva in getting to the ground for conceal- 

 ing itself in the soil beneath the leaves, where it pupates. The other 

 species, curiously enough, does not have this jumping habit, and pupates 

 beneath a silken weh on the stem in the vicinity of the mealy bugs. I 

 believe these insects exert a very considerable intluence on the abundance 

 of their host. They seem to be quite generally distributed in the 

 Islands. 



Several other enemies of the mealy bug are found in the Orient, but 

 they are, for the most part, of minor importance. Still others will 

 undoubtedly be discovered as the w^ork progresses, and many which 

 were of little importance this season may prove to be very effectual 

 during other seasons. 



To show the occasional abundance of enemies of the mealy bugs in 

 the Philippines, I found on one occasion a stem of the Rain tree (Acacia) 

 three and one half inches long by one fourth inch in diameter, infested 

 with Pseudococcus, on which were feeding fourteen ladybird larvae, one 

 larva of the predaceous Initterfly and eighty-five larva3 of the little 

 Diplosis! Needless to say, this tree was soon freed from its pests. 



In the vicinity of Manila a number of parasites of Saissctia hemis- 

 pJiarica were obtained in the hope that they would attack its relative, 

 the black scale, in California. This they seem to do in the insectary, 

 but we have not yet tried them in the field. One Pteromalid attacks 

 the eggs of the scale in much the same way as does our Scntellista 

 cyanea. Two others, Encyrtids, attack the young scale before eggs are 

 laid. One of these is very efficient, and, attacking the young scale, is 

 exactly what we most need in California. The third has proved to be 

 occasionally secondary, and wall probably not be introduced. 



Tentative arrangements have been entered into with the Imperial 

 Department of Agriculture of the Japanese Government, and the 

 Bureau of Agriculture of the Government of the Philippines, whereby 

 they will co-operate with us in our attempt to introduce the natural 

 enemies of California pests. It is our aim to introduce into California 

 every natural enemy of the mealy bug which shows the slightest indica- 

 tion of being of importance in the control of that pest. During the next 

 two years it is hoped that we may be able to work thoroughly the 

 Mediterranean region of Europe and north Africa, where, according 

 to the observations of Doctor Silvestri and Mr. Woglum, the citrus 

 mealy bug is apparently rendered innocuous by natural control. At 

 the same time the work in Japan, and to a lesser extent, in the Philip- 

 pines, will be continued. "While there are many natural enemies of 

 mealy bugs to be found in the tropics, it is from Japan and the Mediter- 

 ranean region that we will obtain our best material. Insects from these 

 countries are much more likely to find our climate agreeable to them, 

 and it will prove much less difficult to ship living insects in good 

 condition from these countries than from the tropics. 



