io8 HOUSE, GARDEN, AND FIELD 



It is quite unnecessary to remind any naturalist that no 

 insect which has once expanded its wings grows after- 

 wards, to pass over such occasional anomalies as the 

 queen of the white ants. Therefore when we see little 

 flies running among the house-flies on the pane, the mere 

 fact that they are much smaller tells us that they do not 

 belong to the same species. Among the most active of 

 these little flies are those named Phora, which may often 

 be distinguished by the nimble way in which they run 

 about, as well as by their hardiness, for they may be 

 found at all seasons of the year. Another very common 

 little fly is the fruit-fly, which lays its eggs in over-ripe 

 or decaying fruit. This is a Drosophila, and though few 

 of us remark it, it is so common in houses that we have 

 only to leave a soft, pulpy fruit, like a tomato, exposed 

 to the air for a few days to get a plentiful supply of 

 Drosophila-larvse. 



I do not venture to describe here the structure of any 

 house-fly. The student who has some knowledge of 

 insect-structure and command of technical methods would 

 find occupation for a few weeks or months in examining 

 any one of the following fly-structures : the antenna, 

 the eye, the proboscis, the haltere, the spiracle, the foot. 



XX. SOLAR IMAGES ON THE PAVEMENT. 



In my garden there is a large concrete pavement, over- 

 shadowed by a cherry-tree. This bright summer morning, 

 as I saunter past the tree, my attention is arrested by the 

 dappled shadow of the foliage, which looks like a dull- 

 purple sheet riddled with holes, some large and some 

 small, but all more or less circular, and with ill-defined 

 edges. Why should they be of that shape rather than of 

 any other ? What I have called holes in the shadow are 

 places where the sun shines through chance openings in 

 the foliage, and as the openings are of all imaginable 

 shapes, one would expect to find endless variety in the 



