GARDEN INSECTS. 



183 



now as to be considered naturalised. Like the bed-bug, it is one 

 of those insects with which an interchange of commerce has 

 presented us. At first it was confined to comparatively few 

 districts, but now it has spread over a vast area, and there is 

 scarcely a village home in which the cockroach is not to be 

 found, it having to a great extent supplanted the chirping 

 "merry" cricket. Being night roamers, cockroaches are liable 

 to be overlooked and their depredations to be put down to other 

 causes. Fortunately, contrary to the general rule with regard 

 to insect life, the cockroach takes a long time to arrive at maturity. 

 Instead of a year being required to complete the cycle of 

 existence, some five years are entailed in the process. Being 

 natives of warmer climes, artificial heat is absolutely necessary 

 to their well-being, and this our plant-houses admirably afford. 

 Here the pests can increase in comparative safety, for although 

 it is possible to destroy vast numbers of the insects, to exter- 

 minate them is out of the question. This difficulty is not a little 

 due to the way nature has ordained the eggs shall be protected. 

 In common with some Orthoptera the cockroaches deposit their 

 eggs in capsules, which are hermetically sealed, and thus defy 

 insecticides and the like. 



I should now like to remark upon two of the new-comers — 

 P. australasicd (fig. 40) and P. americana (fig. 41). Though in 

 general appearance the former bears some resemblance to P. orien- 

 talis, yet in many respects it differs materially. First it is some- 

 what larger and has perfect wings in both sexes, whereas with P. 

 orientalis only the males possess them. The colour is a red sienna- 

 brown, with a yellow streak along the costal margin of the fore- 

 wing at the basal half: the pronotumis almost black, with a yellow 

 margin all round. Despite the specific name, this cockroach 

 does not appear to be a native of Australia. Hr. Dale took 

 it at Sherborne, in Dorsetshire, in 1839, and Mr. MacLachlan 

 noticed it in the Entomologists' Monthly Magazine a few years 

 since from Belfast. At Swanmore Park Gardens, Bishop's Wal- 

 tham, Hants, it is established and does much damage. In the 

 palm-house and in the forcing-pits at Kew, P. australasia is 

 very common, and is found to attack the young shoots and the 

 axillary buds. Phosphorus paste has, however, proved very 

 effective in destroying them. The insects are very lively in a 

 warm atmosphere, but sluggish in a cool one. 



