188 THE CANADIAN ENTOMOLOGIST 



group of three spines, followed by a variable group of not less than four and 

 as many as eight spines; on the distal half of wing the spines of the fore-vein 

 are exceedingly variable, both as regards numbers and disposition; hind-vein 

 with twelve to eighteen regularly placed spines; scale five spines; interior of 

 scale one spine. 



It may be shown, also, that it is the exception, not the rule, to find the two 

 wings of the same specimen equal as regards length of wing, or number and 

 disposition of alar spines. Almost invariably the two wings are dissimilar in 

 some respect. Plate XVII represents outline camera lucida sketches of the right 

 and left wings of ten typical specimens. Rather more than half of the wings 

 examined (59 per cent.) showed the basal portion of the fore-vein with spines 

 "arranged in two groups of 3 to 6, respectively," whilst 28 per cent, were arranged 

 in two groups of 3 and 5, 7 per cent, in 3 and 7, 5 per cent, in 3 and 4, and 1 

 per cent, in 3 and 8. These figures, indicating the differences that are liable 

 to occur plainly, show that the wing characters are of minor value in the quick 

 and ready examination for the determination of the species. 



Abdomen sub-ovate; 10-segmented, tapering abruptly toward the tip from 

 the eighth segment. Dorsal surface of segment 2 to 8 with from eight to ten 

 spines on each segment, the most prominent being on the lateral margins; 

 posterior margin of segment 8 with a fine comb-like structure consisting of from 

 thirty-eight to forty-four teeth; segments 9 and 10 with about ten of the longest 

 and most prominent spines of the body. Total length from tip of vertex to tip 

 of abdomen about 1.26 mm. Colour, head, thorax and abdomen uniformly 

 dark-brown with connective tissue between segments of the abdomen, the 

 tarsi and tibiae shading from light-brown to yellow. Segment 3 of the antennae 

 light brown. 



The wings though slightly tinted with light-brown, when resting over the 

 back, appear, to the naked eye, to be grey in comparison to the dark-brown of 

 the abdomen. Many light coloured specimens, especially those forms which 

 have recently emerged from the soil in the spring, may be frequently observed; 

 this colour difference, however, may be preserved throughout the life of the 

 adult. 



Thrips physapus Linn. 



Thie species is common in British Columbia, under arid and humid 

 conditions, and may be found throughout the entire season. It has been taken 

 commonly off dandelion at Vernon and near Victoria during early April and 

 May, as well as off Ruhus parviflorus flowers during June in Vancouver, and 

 recently it has been found in the blooms of partly frozen garden flowers, during 

 December. Carpenter (7) before the Royal Dubj^n Society in 1900 and again 

 in 1901, draws attention to this species as being destructive to the blossoms of 

 the pear near Dublin, Ireland, causing a failure in the fruit crop. In British 

 Columbia, in Ipcalities frequented by Taeniothrips inconseqnens, Thrips physapus 

 al^so is found to occur, often in similar positions on like plants, frequently as- 

 sociated in the same blossom. 



Thrips tabaci Lind. 

 The adults of this species are known as the "Onion thrips" in British 

 Columbia. The species undoubtedly occurs on a wide range of plants, and is 



