MadSci Network: Zoology

Re: What will a cluster of small yellow green oval eggs become?

Date: Wed Jun 29 10:22:22 2005
Posted By: Tom Clarke, Post-doc/Fellow, Molecular Biology, Sars International Centre for Marine Molecular Biology
Area of science: Zoology
ID: 1119498078.Zo

Hi Maureen,

 	Identifying insect eggs isn't easy at the best of times, and 
unfortunately without photographs it becomes much harder. The best I can 
do in this forum is to make an educated guess that may help narrow down 
the possibilities.  Ideally, you should try to contact an entomologist 
living in Massachusetts who would be familiar with the common insects in 
your area and may be able to recognize either the eggs or the newly 
hatched insects.  The University of Massachusetts at Amherst has an 
entomology department and one of the professors may be able to assist

        There are numerous insects that lay yellow green oval shaped eggs, 
however the fact they were found on an introduced species of plant in a 
cluster (as opposed to in a random clump, on stalks,  or inserted into the 
stem) suggests that these eggs likely belong to either a butterfly or 
moth, a leaf beetle, or a stink bug. Fortunately, Japanese Knotweed is an 
introduced plant with few (if any) natural enemies in the United States.  
Its very unlikely that whatever insect the eggs belongs to actually eats 
Japanese Knotweed and this means that the eggs probably aren't from a leaf 
beetle, butterfly or moth.  These insects produce larva that cannot 
disperse far from the site of hatching, so they tend to lay their eggs on 
the same plant the larva will feed on during the early part of their 
life.  (There are a few exceptions, including species of caterpillar that 
disperse after hatching by floating on strands of silk - "balooning" - and 
some butterflies that will lay their eggs on unsuitable host of no 
suitable plant can be found.)  In contrast, newly hatched stink bugs are 
very mobile and many species are predators.  This means that the parent 
will lay their eggs on any conveniant plant, since the newly hatched bugs 
are fully capable of migrating to find food. 

	Probably the best way to identify the eggs is to simply see what 
hatches out.  Newly hatched caterpillars will always have a set of grooves 
on their head that resembles an upside down V.  Newly hatched beetle larva 
can look similar to caterpillars, but they will never have the V shaped 
grooves. If the eggs belong to a stink bug or other true bug, what will 
emerge will look like a miniature wingless adult.  It is sometimes 
possible to keep the insect alive until it has gone through several molts 
by feeding it on its host plant if itís a herbivore.  Older insects are 
easier to identify to genus or species than younger insects, and adults 
are much easier to identify than immature insects.  If the insect is a 
carnivore, however, it will be difficult to rear in captivity, and 
probably the best thing for it would be to release it near where you 
originally found the eggs.

	I hope I was able to help,


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