PSYCHE. 



125 



ber of ecdyses is twenty. The Neurop- 

 terous Ascalafhus (Helecomitus) iti- 

 simiclans of Ceylon moults three times 

 before pupating. Among the Mecop- 

 tera Felt has shown tliat Panorpa 

 riifescens moults seven times. 



In Coleoptera the normal or usual 

 number is not definitely known ; Meloe 

 moults live times; Phytonomwi piiiic- 

 tatus, the clover leaf weevil, moults 

 thi'ee times, according to Riley, who 

 has observed that Dertnestes vidpinus 

 passes through seven larval stages. 



In the breeding jars, with plenty of food and 

 a constant temperature of from 68'' to 78^ F., 

 the larvae cast their first skin in from fonr to 

 nine days, the great majority moulting at 

 seven days. Under the same conditions the 

 second skinwascastat from fourtosevend.iys, 

 the majority moulting at six days; the third 

 skin at from three to six days, the majority 

 mouUing at five days; and the fourth skin at 

 from three to six days, the majority moulting 

 at five days; the fifth skin at from five to 

 seven days, and the sixth skin at six days. 

 There are thus seven larval stages. (Report 

 for iSSs, p. 260.) 



Riley has ascertaineil th.it by rearing iso- 

 lated larvae of Tenehrio molitor. one after 

 being kept nearly a year had moulted eleven 

 times, when it died. A second larva hatched 

 June 5, had moulted twelve times by June icth 

 of the following year (1877), when it also 

 died. Of T. oh^curus three larvae were 

 reared to the imago state. One moulted 

 eleven times by August 30th of the same 

 year, pupated Jan. 20th, 1S77, and finally be- 

 came a beetle Feb. 7, 1877. The other two 

 both moulted twelve times and reached the 

 imago state Feb. iS and March gib respec- 

 tively. "All were, as nearly as possible, 

 under like conditions of food and surround- 

 ings, and in all cases the moult that gave the 

 pupa is not considered among the larval 

 moults." 



Two larvae of the museum pest {Trogo- 

 derma tarsale) were kept by Rile_\- in a 

 tight tin box with an old silkworm cocoon. 

 " They were half grown when placed in the 

 box. On NovemberSth, 18S0, there were in 

 the box twenty-eight larva skins, all verv 

 much of a size, the larva having apparently 

 grown but little. The skins were removed 

 and the box closed again as tightly as 

 possible. Recently, or after a lapse of two 

 years, the box was again opened and we 

 found one of the larvae dead and shrivelled 

 up; but the other was living and apparently 

 not changed in appearance. There were 

 fifteen larva skins in the box. We cannot 

 tell when the one larva died, but it is certain 

 that within a little more than three and a half 

 years, two larvae shed not less than forty- 

 three skins, and that one larva did not, during 

 that time, appreciably increase in size. " We 

 know of no observations which indicate the 

 normal or average length of life, or number 

 of moults in either Tenehrio or Trogoderma, 

 but it is safe to assume from what is known, 

 in these respects, of allied species, that in 

 both the instances here referred to, but 

 particularly in the case of Trogoderma, de- 

 velopment was retarded by insufficient nutri- 

 tion and that the frequent moulting and slow 

 growth resulted therefrom and were corre- 

 lated." * Further observations such as these 

 are greatly needed. 



Of the Siphonaptera the common cat 

 and dog flea {Ptilex serraiiceps) moults 

 three times before pupating (Howard). 



In Lepidoptera the usual or aveiage 

 number of moults is four, but the number 

 varies considerably, the greatest number 

 yet known occurring in Phyrrarctia 

 Isabella which, Dr. Dyar informs me, 

 moults ten times. 



From Dyar's observations it appears 

 that thei-e are usualh' five larval stages, 



turalist, xvii. May 1883. pages 547-548. 



