THE ENTOMOLOGIST. 167 



May there was not an Aphis to be seen on a mostly-shaded 

 row of elder-shoots by a pond. At the end of this week there 

 were many hundreds of thousands, and the usual attendants 

 on clusters of Aj^hidcs were not wanting — such as the 

 Aphidius watching them close by, the Aphelinus skipping on 

 them, the ant running over thcni, the ladybird nibbling them, 

 and various Muscidaj feeding on their honey. Few kinds of 

 Aphis multiply so quickly as the elder Aphis, which is a 

 remarkable instance of the shortness of time in which life is 

 divided and individualised as organisms by means of the 

 abundance of elder sap. The lime Aphis is one of the 

 slowest in increasing: it was full grown in April this year, 

 but was not more numerous on the same leav^es at the end of 

 a month. At the end of May little specks of honey may be 

 seen on both sides of a lime-leaf, the surface of the leaf being 

 often reversed by a slight wind. These specks are almost 

 always few and irregular, notwithstanding the abundance of 

 upper leaves, and quite resemble the specks, which are much 

 more numerous, on the sycamore. A sycamore-leaf may be 

 seen with one half quite covered with honey, of which 

 substance there is no trace on the other half, the first half 

 being just under a colony of Aphides on a leaf above ; and at 

 the end of May I saw just the same appearance on a lime-leaf, 

 half of which was under another leaf, on whose under side 

 there was an unusually great number of the lime Aphis. 

 I have observed nearly all the species of Aphides that have 

 been recorded as British, and in all cases they emit honey, 

 and in every instance there has been no honey without them. 

 — Francis Walker. 



[The reader is referred to a paper on this subject, reprinted 

 (Enlom. vi. 463) from the 'Gardener's Chronicle.' Mr. 

 Walker's note appears to have reference to this note, but he 

 does not mention it. — Edtvard Newman.] 



Is Heat ilie Chief Agent in Insect Development ? — We 

 naturally answer in the affirmative, and indeed reasonably 

 so, since ranch or little experience all points to the same 

 conclusion. A warm spring induces early developments, and 

 a hot summer causes a second brood of species, wliich in 

 ordinary seasons make but one appearance ; to these trite 

 assertions every reader of the ' Entomologist' can bear greater 

 or less testimony. And although we sometimes read of the 



