EXPERIMENT STATION BULLETINS. 



247 



THE RED SPIDER. 



{Tetranyckus telarius Linn.?) 



A visit to the orchards at the South Haven Fruit-testing Sub-station was made 

 on September 5, and at that time many trees in that region were affected with a 

 mite very closely resembling the red spider, and which probably will prove to be that 



Fig. 1. Red Spider, Tetranyckus telarius, enlarged. (Original.) 



species. Fig. 1 shows one of these mites. It is probably well known that the red 

 spider is not a spider at all, but a mite, and so small that it requires very good eyes 

 to detect it, and a good magnifying glass to see any detail. 



The mites here did not confine their attention to one tree, but apparently the same 

 mite infested plum, apple, peach and chestnut. It was also seen on honey locust. The 

 injury was mostly connned to apple, plum and peach. 



Unlike the ordinary work of the red spider, no threads of silk were seen, though 

 these may have been present and escaped notice. The little mites were seen in quantity 

 congregated on the under side of the leaves, though they worked on both sides of the 

 chestnut leaves. The leaves of the apple and plum curl downward and the surface 

 becomes uneven and unhealthy looking, almost blistered. The eflfect on the young 

 trees is quite serious, stopping the growth and stunting the tree. Small apple trees, 

 two or three yeat-y old, badly affected, showed very little grow^th during the past season. 



The red spider and all its allies, thrive best in a warm, dry atmosphere, and, as the 

 past season has furnished ideal weather from the standpoint of the mite, it is easy to 

 understand why they became so numerous. It is not likely that they will often become 

 so serious as during the past summer, because our summers are usually more moist. 

 This mite has. however, appeared many times before, both in Michigan and in other 

 states, and has proven itself well worth being placed in the list of out-door pests. Other 

 observers record it, or something very like it, on strawberry, grape, garden plants, pear 

 and other plants. Mr. T. T. Lyon records it on plum in 1875.* 



REMEDIES. 



In the greenhouse, the remedy is moisture, a spray of water being considered the 

 best remedy when the plants will stand it. Out of doors almost any contact insecti- 

 cide, such as kerosene emulsion, soft soap and water, whale oil soap, etc.. will keep 

 the pest in check if it can be made to reach it. The leaves being curled slightly and 



' Rep. Secy. State Pomological Societj- of Michigan, l874-r), pj). 233-249. 



