158 BEITISH LEPIDOPTEEA. 



of Fumea nitidella, and filled their cases with eggs by pushing in their 

 ovipositors. The Solenobiid females, however, when emerging, drag 

 the pupa-skin out of the larval case, the pupa-skin at first hanging loosely 

 from the free end of the case and afterwards falling down, :;: so that the 

 female lays her eggs directly in the case ; the eggs are laid almost as 

 soon as the ? is excluded," and Siebold says that " they possess such 

 a violent impulse to lay their eggs that, when removed from their cases, 

 they let their eggs fall openly." He further states that " all the eggs 

 of these husbandless Solenobias, of whose virgin state he was most 

 positively convinced, gave birth to larva3." On the other hand Siebold 

 states that the females of Fumea put off their egg-laying until copula- 

 tion takes place, and that when this does not happen they die without 

 laying their eggs. Bacot has obtained undoubted parthenogenetic 

 progeny from the Solenobia that Hamni obtains near Wellington 

 College, and Chapman observes that as soon as females from that 

 locality emerge, they begin almost . at once to thrust the ovipositor 

 between the pupa- shell and the larval case to oviposit in the latter. He 

 notes that as the process of laying is going on, the body of the female 

 does not shrink in size, but is distended with air so as practically to 

 maintain its original volume. This gives it a greater purchase, and 

 enables it more readily to lay its eggs within the case. When, how- 

 ever, the egg-laying is finished the body speedily collapses. The 

 question here arises whether there be but one parthenogenetic form — 

 rightly called lichenella — and whether the so-called parthenogenetic 

 forms of triquetrella, jrineti, &c, are referable to this same species. In 

 connection with this it must be borne in mind that Hofmann asserts 

 that he has had a male 8. triquetrella pair with one of these partheno- 

 genetic females, and concludes that the parthenogenetic form also is 

 8. triquetrella. It is possible, of course, that each species has its own 

 parthenogenetic form, and that the various observers are correct as to 

 their references to the different species. 



This, one of the most difficult matters connected with the partheno- 

 genesis of the Solenobiid species, was first raised by Hofmann, who sur- 

 mised that insects he bred were respectively ' ' parthenogenetic' ' and ' ' sexu- 

 ated" forms of the same species — S. triquetrella and 8. pineti. Have any 

 of the species of Solenobia two forms — sexuated and parthenogenetic ? 

 The evidence offered by Hofmann as to S. triquetrella is not conclusive, 

 but is so interesting that we offer the following summary. Hofmann 

 notes that he has found cases (of what he considers to be S. triquetrella) 

 over large districts in the neighbourhood of Eatisbon (on fir-trunks 

 and pear trees) and Erlangen (on fir- and oak-trunks), but never in 

 numbers, appearing to be more common on the margins of woods, and 

 usually on old trees, whilst single cases are found on grass culms, 

 low plants (such as Spartium scoparium) ; all the cases are flattened 

 anteriorly, so that the ventral surface lies flat on its resting-place, the 

 cases producing (at the end of March and commencement of April) 

 only female specimens. He observes that after emergence they 

 remain only about a quarter of an hour with raised abdomen, and 

 then begin (by inserting the ovipositor between the pupal skin and 

 larval case) to fill the empty case with eggs, which are mixed with 



* This does not happen until the ? has finished laying her eggs, and not then 

 without some external interference (at least in S, lichenella, &c). 



