2 PROCEEDINGS OF THE NATIONAL MUSEUM vol.68 



not crawl into the water and become drowned. This bottle should 

 then be set in a battery jar with muslin tied over the top — if set under 

 a bell jar the condensation water on the <Tlass will wet the wings of 

 the flies. From galls of this type come active, fully-winged adults 

 of both sexes whose adult life is short. 



The more solid autumnal galls on oak, maturing and dropping 

 just before or with the leaves, contain at that time when they are 

 usually gathered a scarcely visible larval cavity in a thick translu- 

 cent nutritive layer w^hich is used up slowly during the Avinter. Such 

 galls should be kept under more or less natural conditions out of 

 doors on the ground in some sort of wire cage. Select a shady spot 

 in the woods if possible where there is a deep layer of leaf mold, 

 safe from molestation and from fire in summer and well buried under 

 snowdrifts in winter. Mice and squirrels are liable to destroy collec- 

 tions unless wire cages are used. Labels inside should give locality, 

 date and host and may be Avritten with waterproof ink on paper and 

 then dipped in melted paraffin or better inclosed in a well-corked 

 7 by 25 mm. vial. The year of collection should not be omitted in 

 the date. Two winters .often pass before any flies appear and then 

 some may emerge each spring for several years. The larvae trans- 

 form in the fall before they emerge and remain as adults in the 

 galls during the winter to come out when conditions are suitable in 

 the spring. Adults may often be secured by cutting open galls 

 in the late fall or winter but in this case it is better to let them 

 crawl about in a vial until the chitin hardens and takes on its normal 

 color rather than to kill them at once in a cyanide bottle. Adults 

 from galls of this type are all agamic females and are comparatively 

 long-lived, often surviving for a month or more in captivity. Many 

 species normally emerge in the late fall, for example, all those of the 

 genus Disholcaspis (whose galls on twigs are in general bullet- 

 shaped, detachable but not deciduous) and many wingless agamic 

 forms such as species of Acraspis, Xanthoferas, Zopheroteras, etc. 

 Some wood}?^ stem swellings on oak become so hard after being gath- 

 ered that the insects even if they have already transformed can not 

 chew their way out and it is better to cut them out. These are but 

 general suggestions for the beginner and their value is indicated by 

 the fact that the writer knows many kinds of galls which he has never 

 yet been able to rear. A single gall casually collected is seldom worth 

 the trouble of rearing. It may be the normal reaction of the plant 

 to the Cynipid maker and it may be quite abnormal if that struc- 

 ture is modified by guests or parasites and some field observation 

 may be necessary to determine whether this is the case. Collecting 

 of value usually requires definite search for quantities of material 

 with the object of rearing in view. When gathering galls from 



