70 



THE REPORT OF THE 



No. 19 



A CATALOGUE OF THE GALL INSECTS OF ONTAEIO. 

 By Tennyson D, Jarvis, 0. A. C, Gtjelph. 



Tke insects which produce galls are confined to the following orders : 

 Acarina, which are not true insects, but mites ; the Diptera or flies ; the 

 Hemiptera, or bugs; the Lepidoptera, or moths and butterflies; the Cole- 

 optera, or beetles; and the Hymenoptera, or bees, wasps, ants and sawflies. 



Their food-plants cover a wide range, some twenty-six orders of plants 

 being affected by them. Some species show a decided preference for certain 

 groups of plants as the following table will show. 



Acarina. 

 Family — Eriophyidoe. Gall Mites. 



This is a family of microscopic mites which are quite curious and 

 unusual in structure. They have only two pairs of legs and the abdomen 

 is long and striated. These striations, which dilfer in the different species, 

 and differ in number on the dorsal and ventral surfaces are of considerable 

 value in classification. The galls produced vary in form, but are always 

 open or provided with an opening through which the mites pass in and out. 

 They are generally lined with minute hairs (trichomes) which may be 

 simple or branched. The different types of phytoptid galls are shown below, 

 figures 20 to 28. 



