9 
you immediately become involved with the ants. It is a well 
authenticated fact that the ants protect their benefacors from the 
attacks of parasites, and in the case of the mealybug of the pine- 
apple, they minister to their comfort still further by providing 
the semi-obscurity which this species desires by packing up pel- 
lets of soil to roof them over. You can see this at any time on 
a pineapple fruit. And this feature of their association is respon- 
sible for greater damage to fruit than any other single cause. The 
covering of dirt, by shutting off the evaporative influence of the 
surrounding air, causes moisture to collect on the surface of the 
fruit, which softens the skin, causes it to break and thus induces 
rot. They also habitually run along the roots and are responsible 
for some of the retardation of growth which results from root 
destruction. Ant infestation is more noticeable in summer 
months than in winter, as the cold, wet weather and flooding 
which occurs during the winter months undoubtedly weaken ant 
colonies, and this decimation is certainly reflected in the reduction 
of mealybug infestation during the winter months. Ant infesta- 
tion increases with the age of the fields, and when the fields 
become so overgrown that cultivation is no longer practical, they 
make the mealybug control problem extremely difficult. 
Now, I believe I have shown that these two enemies of the 
pineapple are capable of causing considerable injury to the 
plants, particularly the fruits, and it seems to me a natural corol- 
lary that they should be prevented from accomplishing this result 
if possible. As the insects suck their food from the cells of the 
plant, naturally they cannot be reached by a stomach poison like 
arsenic. It is therefore necessary to use other means of killing 
them, either poisonous gases or vapors, caustics, asphyxiation by 
a mechanical stoppage of their breathing apparatus or washing 
them off their hosts. But here the question arises, To what ex- 
tent does this injury go; and provided it can be stopped, will the 
effort required to effect the purpose pay? That is to say, does 
the damage expressed in loss of fruit amount to as much as it 
would be necessary to expend in labor and materials to prevent 
it? That is entirely a practical question which can only be an- 
swered after experimentation. We are trying to arrive at some 
conclusion in this regard at the present time. My only excuse 
for not having complete data already is that hitherto little in- 
terest has been displayed in the matter. I presume other fac- 
tors in the production of fruit have proved of greater and more 
vital importance to the industry, and have crowded out a consider- 
ation of this one. I know that for some years it was a common 
practice to use tobacco dust to discourage the mealybug. It has 
been conceded that the effect was salutary. But the practice was 
discontinued, probably because other field operations absorbed all 
the labor and material which could be applied. I have recently 
experimented on a large scale with three different contact insec- 
ticides applicable to the mealybug and scale, namely, nicotine. 
