The Aphis-Lion. 



4; I 



case of the commoiiL'St of them,^ which, thoui^h s])L'cian\' ck'structive to the wall 

 mason-wasp,- will lay her eggs in the nest of any species that comes handy. The 

 spin3'-footed mason-wasp,^ which builds temporary towers to keep out these 

 ruby-wasps as far as possible, is victimized by two species of the parasites,* and 

 wherever this mason-wasp is plentiful these two ruby-wasps will be common also. 

 Dr. T. A. Chapman, who investigated this matter many years ago, found that 

 one-third of the grubs of the spiny-footed mason were destroyed by tlie grubs of 

 the ruby-wasps. The two species effecting this destruction have different methods 

 of attack. Xeglecta a})pears on the wing in May at the same time as the earliest 

 of the spiny-foots ; bidentata does not show herself until about three weeks later, 

 when the last of the spiny-foots are emerging. 



If one of the first nests of the spiny-foot be examined a few days after it has 

 been closed, it will probably be found to contain neither egg nor grub of the mason, 

 but a grub of neglecta may be there instead feeding upon the green caterpillars, 

 and it may be presumed that she has already eaten the egg or grub of the mason. 

 By the time bidentata emerges, the mason-grubs 

 that have escaped the attack of neglecta are full 

 grown and spinning their cocoons. From various 

 causes man\- of the burrows of the mason-wasp 

 remain uncompleted, and the last-made cells are 

 only protected bv the wall of clav which she has 

 intended to be onlv a dividing wall between this 

 cell and another which she had purposed making. 

 Bidentata is able to bore through this and get access 

 to the cell. With her egg-placer she pierces the 

 cocoon and lays her eggs inside ; in some cases she 

 has not this trouble, for the cocoon is not quite 

 finished, and she can la\- her eggs on the mason- 

 grub with ease. Tlie cuckoo-grub nips a fold of 

 the skin in its jaws and, without cutting through 

 the latter, sucks awa\- all the substance of the 

 mason-grub and grows rapidly, changing its skin four times, at intervals of onl\- 

 about two days. There is little save colour to distinguish the grubs of host and 

 parrsite ; the former is \-ellow and the latter whitt'. 



The Aphis-Lion. 



The four-winged flv whose active grub is known as the aphis-lion^ has been 

 designated the brown lace-wing to distinguish it from the green lace-wing or golden- 

 eye. ^ Most people would sav it is the same thing with wings of another colour. 

 Yet if the two are put side by side and closely examined there will be found points 

 of difference which, in conjunction with some difference's of internal structure and 

 life-history, have induced naturalists to put tliein apart m separate groups. 



In most species of golden-eyes the larva goes about openly upon plants where 

 the aphis or green-fly abounds, and docs his best to reduce the numbers of the 

 pest. The lar\'a of the brown lace-wing carries on the same good work, but possibly 



1 Chrysis ignita. ^ Odvnerus pariftiiin. » O. spinipts. * Chrysis bidentata and 



C. nt-ykcta * Hcmerubius. " Chrysopa. 



Photo by\ [E. St,:t>, l.L.S. 



RuBY-T.\iL Wasp. 



TIksi' liny wasps — tho photograph shows out- 

 four times larger than the actual size — are 

 e.xceedingly brilliant Insects, the hind-body 

 being bright red with a high metallic pohsh 

 which flashes in the sunshine. 



