1918] Observations of Pilophorus Walshii 95 



habits under natural conditions. However, one was noted with 

 its beak inserted into a large scale, which it punctured in three 

 other places before moving away. Another nymph, confined in a 

 tube with a scale-infested twig, was observed directing its beak 

 into the scales as if feeding on them. 



Without further observation I cannot say whether the bugs 

 commonly feed on scales or 'whether they were not merely 

 sucking plant juices from the bark beneath the scales. 



VALUE AS AN APHID DESTROYER. 



In order to test the value of the species as an aphid destroyer 

 an experiment was performed, using two small shoots of Spiraea 

 infested by these insects. Fifty aphids were allowed to remain 

 on each shoot and care was taken to have them free from 

 predaceous insects. Three nymphs of Pilophorus were placed 

 on one shoot and none on the other, and both were covered with 

 bell-jars. Two days later, six aphids were found alive on the 

 first shoot, but ninety-one were present on the control, many of 

 them being small newly-born individuals. 



The experiment was repeated using the same number of 

 aphids, and with two adults of Pilophorus in one bell-jar. 

 After twenty-four hours one of these had been on the shoot for 

 some time, but the other was still crawling about the bottom 

 of the jar. This shoot contained forty-one aphids, while the 

 control had sixty-five. Both adults were placed on the shoot 

 and the experiment was allowed to run another day, when the 

 first shoot had twenty :three aphids and the control had eighty. 



These experiments show that this species, if present in 

 sufficient numbers, might be an important factor in holding in 

 check the natural rapid increase of aphids. 



IN RELATION TO ANTS. 



The aphid-infested apple leaves are usually attended by 

 ants, among which a large black species is common. Both 

 nymphs and adults of Pilophorus are very rapid runners and 

 carefully avoid meeting the ants. The bugs can see a large 

 moving object, such as the hand, at a distance of one foot or 

 more, and can detect the ants when they are several inches away. 

 They are thus able to keep on the opposite side of a branch or 



