Insects Visiting Blossoms of Spirea 139 
flowers in search of food as some of them when taken were 
observed to have their probosces uncoiled and searching 
about among the flowers for the nectaries. 
In arriving at conclusions regarding seasonal distribution 
and seasonal succession of insects from data such as here 
presented, it is wise to scrutinize such data with the greatest 
of care. It has already been shown that the collections were 
made as nearly as possible at intervals of seven days. But 
it was considered to be more important that the climatic 
conditions — temperature, moisture, light and wind — 
should be as nearly uniform as possible, than that the interval 
should be exactly one week. Of course, some variation of 
these conditions were inevitable and unavoidable but the 
collection days were as uniform as possible and the results 
are believed to be entirely trustworthy in this respect. 
The validity of conclusions from such data is also depend- 
ent upon the uniformity with which each species of insect 
seeks the blossoms from which the collections are made. 
Thus in the case of some of the insects from spireea blossoms, 
it is believed that the number taken on any date represents 
a fairly definite per cent of those actually in the adult con- 
dition at that time. In other cases it is believed that the 
numbers taken have not even an approximately definite rela- 
tion to the numbers actually out. The object of the insect’s 
visit to the blossom has much to do with the reliability of 
the data for the purpose mentioned. Thus, if the insect is 
in search of honey or of pollen or of both of these, and if 
observations have shown that the blossoms in question are 
the favorite source of this material, the data should be reli- 
able. If the insect visitor is in search of insect prey, the 
data is not so valid unless it is established that the predaceous 
or parasitic form is in search of some particular species 
which is usually to be found only on the flower in question. 
Tf the insect is an accidental or casual visitor which has 
happened to alight upon the flower the data is valueless, as 
the number taken from flowers would bear no fixed relation 
to the actual numbers at the time. 
