20 B.C. ExTOJiOLOGicAL Society. 



serves to coutaminate the insects which come to feed on it, and if such an insect 

 visits a blossom within a short time after, the honey-glands of the latter are likely 

 to become infected. The nature of the insects visiting these running cankers affords 

 scope for much further observation. Probably many kinds of flies may serve to 

 carry the disease. Wasps have also been rather frequently recorded as visiting the 

 cankers, but I am not sure that these insects are very common visitors of orchard 

 blossoms. Chiefly on the strength of the observations of JI. B. Waite, of the United 

 States Department of Agriculture, the honey-bee has been put down as a carrier of 

 the first infection, but I have been able to find very few other trustworthy observa- 

 tions of lioney-'bees visiting the cankers. We also know that many moths are 

 strongly attracted by sticky, sweet substances, and that the " sugaring " method is 

 a common one with entomologists for collecting night-flying Lepidoptera, and I think 

 it is quite possible that these insects may play a part in disseminating flre-blight. 

 There are, of course, rather grave practical difficulties in the way of securing proper 

 data on these points. In the first place, it would be necessary to have running 

 cankers under observation, both night and day, for some time. Such cankers would 

 also have to he freely exposed, and in a region where fire-blight offers such difficul- 

 ties in the way of its control an experiment of this kind would not be likely to be 

 viewed with much favour by neighbouring orchardists. We should be very glad, 

 however, to receive specimens of any insects which may happen to be found on 

 running cankers about blossoming-time. 



A question sometimes asked is whether the blight bacillus can live through the 

 winter season in the hive or nest of the bee. If so. it is conceivable that bees 

 might become contaminated with the germs and carry the infection to the flowers 

 during their honey-collecting trips in the spring. So far as the honey is c-oucej-ned. 

 there would seem to be very little danger. Nectar, it is true, affords a medium 

 suitable to the rapid multiplication of the Wight bacillus, but the nectar of a flower 

 is different in composition from the stored honey. Such examinations as have been 

 made of comb-honey have shown it to be almost uniformly sterile. 



It is at the same time worthy of note that germs of a rather remarkable nature 

 can be isolated from the intestine of the honey-bee. Dr. Franklin White states that 

 lie has thus isolated the colon bacillus and that of liog-cholera. Whether the fire- 

 iblight bacillus could exist for any length of time in the intestinal tract of the bee 

 or not. I do not know for certain, and I do not know of any work on this phase of 

 the subject. I should think, however, it would be very unlikely. In the first place, 

 the germ is not a spore-former, and has therefore only very limited powers of 

 resistance to unfavourable conditions ; and, secondly, being adapted for plant- 

 l^arasitism, the conditions of temperature, ox.vgen supply, etc., in the intestines 

 would probably be very unsuitable. The same objections would probably apply in 

 a less degree to the possibilit.v of the germs wintering over elsewhere in the hive. 



Once the disease has been introduced into the first blossoms, there is no doubt 

 that subsequent blossom-infection results from bees visiting such infected blossoms, 

 becoming smeared with the germs and then leaving them behind in the healthy 

 flowers visited. The number of flowers which may be infected in this way after 

 one visit to an infected flower is probably very large, although I have no data. 

 Surprise is often expressed that so many blossoms on a tree should show the blight 

 almost simultaneously. Considering, however, the method by which It is spread, a 

 very few contaminated insects would be sufficient to explain this. 



It is sometimes stated that blossoms may show the effect of blight before they 

 have opened. In this connection it is to be noted that there Is liability of confusion 

 between the effects of blight and of certain insects — e.g.. tarnished plant-bug. On 

 the other hand, it is quite possible that some small insects may visit cankers and 

 afterwards creep into unopened blossom-buds. More observation is required in this 

 connection. 



A question of practical importance is whether there is any relation between 

 the number of bees Itept and the prevalence of blight. In some parts of the 



