118 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi.' 



"found Thrips prejang upon the gall-making larv;^ of more than 

 twenty different galls, so that there is now no manner of doubt in my 

 mind that Thrips is a true cannibal insect"' (132). All recorded 

 obseryations which I haye seen seem to agree that such gall-fre- 

 quenting forms belong to the Phloeothripidse, and in yery many of 

 the cases noted it is said that they are in the pupal stage (123). 



It seems to me entirely possible that in many cases their presence 

 in the gall may be incidental, they haying entered it for protection. 

 It is impossible for Thrips to make for themselves an entrance into 

 any closed gall, and when present in such it can onl}' be after the exit 

 of the gall maker or some parasite upon it, so here certainl}-^ the Tlwips 

 is not predaceous. Furthermore, it does not seem improl)a])le from 

 what we know of the food ha])its of the Tubulifera, which feed mainly 

 upon leayes or decaying wood or fungi, that they may live peacefully in 

 company with the true maker of an open gall which they can readilj 

 enter, hnding there the same favorable conditions for abundant foo| 

 and a secure retreat as does the gall maker. Ph3dloxera galls ha^ 

 often been found to contain Thrips, l)ut the same doubt exists as t^ 

 the real purpose of their being there. ^\'^alsh states that he has founc 

 six or seven i"ed Thrips pupa^ in nearly every gall of PhylJoxeTG 

 caryae-foJliv. This o))servation shows-plainly one object for which these] 

 insects seek out and enter galls, as a safe refuge during pupation,] 

 and this will account for the frequent presence of larvje and adults ir^ 

 both inhabited open galls, as those of Phylloxera, and deserted close] 

 galls, as those of Cynipida?. It may be true that Thrips prey upon thi 

 gall makers, but further observations upon this point are desirable 

 before we can fully accept that conclusion. 



'"'' Thrips fhyUoxer •a''''' of Riley's manuscript (one of the Phloeothri- 

 pidee) is said hj him to "do more than any other species to keep the 

 leaf-inhabiting grape Phylloxera within bounds" (165). A species 

 Phlwothrips has been observed destro3^ing eggs of the Gypsy Mot| 

 (353). 



Some species of Thripidro have been observed feeding upon othei 

 insects and are undoubtedly beneficial. Thi'lps 6-maeulatus has beei 

 repeatedly observed feeding upon "mites" or "red spiders," an] 

 other species have been said to do the same. Riley observed a Thripl 

 larva feeding upon the eggs of the Curculio in Missouri (143a and 114) 

 Thrips trifasciatus Ashmead is apparently predaceous and was observe] 

 feeding on the cotton Aleurodes {Alewrodes gossypii) in Mississipj 

 (386). I have occasionally noticed that under the influence of cor 

 finement without plant food Anapliotl trips striatns^ which is certain] 

 normally her})ivorous, becomes cannibalistic and will feed upon its owi 

 species. 



FJoicer fertilizers. — It is very probable that a few flowers, of whic! 

 the "wild pansy" is one, are fertilized by Thrips, although such a" 

 relation must be exceptional. Few flowers are adapted to thus profit 



