70 PROTECTION OF PLANTS — 1923-24 



The Riley cage, which needs no description, is eminently useful for rear- 

 ing leaf -eating larvse which have to be furnished with fresh food at frequent inter- 

 vals. The leaves of the food plant can be kept reasonably fresh by placing 

 the twigs or shoots in narrow necked jars containing water and the larvse can 

 be preserved from drowning by fitting the jars with cheesecloth or cotton bat- 

 ten stoppers. 



Ground cages (figure 7) with wire cloth or cheese cloth sides and tops and 

 with sliding doors are valuable for studying the emergence, etc., of insects such 

 as fruit flies and sawflies which spend part of their life history in the soil. 



Glass vials in Marx trays (figure 8) may be employed for rearing certain 

 larvse such as ladybird beetle grubs. At the present time we are using glass 

 vials in our codling moth investigations. The vials with one larva in each are 

 placed in pockets in burlap bands (figure 9) and the bands are tied around the 

 trunk of the tree. The larva in this way are kept under conditions which 

 closely approximate those of codling worms under the bark. It might be 

 of interest to mention here that in replacing a band which has been removed for 

 examination, care is taken to put it back in the same position, so that the insects, 

 say on the south side of the tree, remain on that side of the tree until they emerge 

 as adults. 



Cheesecloth cages of different kinds are of value in field or plot work, where 

 it is necessary to cover such plants as raspberries, currants and small grape 

 vines. The cage shown in figure 10 has one end pinned to the sides with safety 

 pins, thus making it possible to lift up the cheesecloth to any height desired in 

 order to see what is going on inside. 



Some of His Work 



An investigation on a fruit insect pest generally comprises a careful study 

 of its life history and habits under insectary and orchard conditions ; a study of 

 the injury to its host or food plants; a study of the effects which meteorological 

 conditions, cultural practices and orchard environment have on its develop- 

 ment and prevalence; a study of the parasitic and predaceous insects, birds, 

 fungus and bacterial diseases which ma}^ attack it and of the effects which mete- 

 orological conditions, orchard environment, etc., have on them, and finally a 

 study of methods of prevention and control. 



In the insectary experiments the insects should be reared under conditions 

 as nearly natural as possible. This calls for some ingenuity in devising and 

 trying out various breeding paraphernalia. A simple, uniform system of 

 labelling the cages, etc., should be adopted in order to simplify the recording of 

 observations and in order to eliminate to as great a degree as possible the chance 

 of mistakes being made. What I have in mind can be most easily explained 

 by describing the system we use. In aphid experiments the stem mothers 

 would be labelled as follows : 1„ 2^, lOi, with the date of hatching immediately 



